This is gnutls.info, produced by makeinfo version 6.3 from gnutls.texi.

This manual is last updated 23 March 2015 for version 3.3.29 of GnuTLS.

Copyright (C) 2001-2013 Free Software Foundation, Inc.\\ Copyright (C)
2001-2013 Nikos Mavrogiannopoulos

     Permission is granted to copy, distribute and/or modify this
     document under the terms of the GNU Free Documentation License,
     Version 1.3 or any later version published by the Free Software
     Foundation; with no Invariant Sections, no Front-Cover Texts, and
     no Back-Cover Texts.  A copy of the license is included in the
     section entitled "GNU Free Documentation License".
INFO-DIR-SECTION Software libraries
START-INFO-DIR-ENTRY
* GnuTLS: (gnutls).		GNU Transport Layer Security Library.
END-INFO-DIR-ENTRY

INFO-DIR-SECTION System Administration
START-INFO-DIR-ENTRY
* certtool: (gnutls)Invoking certtool.	Manipulate certificates and keys.
* gnutls-serv: (gnutls)Invoking gnutls-serv.	GnuTLS test server.
* gnutls-cli: (gnutls)Invoking gnutls-cli.	GnuTLS test client.
* gnutls-cli-debug: (gnutls)Invoking gnutls-cli-debug.	GnuTLS debug client.
* psktool: (gnutls)Invoking psktool.	Simple TLS-Pre-Shared-Keys manager.
* srptool: (gnutls)Invoking srptool.	Simple SRP password tool.
END-INFO-DIR-ENTRY


File: gnutls.info,  Node: Certification,  Prev: Contributing,  Up: Support

B.5 Certification
=================

Many cryptographic libraries claim certifications from national or
international bodies.  These certifications are tied on a specific (and
often restricted) version of the library or a specific product using the
library, and typically in the case of software they assure that the
algorithms implemented are correct.  The major certifications known are:
   * USA's FIPS 140-2 at Level 1 which certifies that approved
     algorithms are used (see
     <http://en.wikipedia.org/wiki/FIPS_140-2>);
   * Common Criteria for Information Technology Security Evaluation
     (CC), an international standard for verification of elaborate
     security claims (see
     <http://en.wikipedia.org/wiki/Common_Criteria>).

Obtaining such a certification is an expensive and elaborate job that
has no immediate value for a continuously developed free software
library (as the certification is tied to the particular version tested).
While, as a free software project, we are not actively pursuing this
kind of certification, GnuTLS has been FIPS-140-2 certified in several
systems by third parties.  If you are, interested, see *note Commercial
Support::.


File: gnutls.info,  Node: Error codes,  Next: Supported ciphersuites,  Prev: Support,  Up: Top

Appendix C Error Codes and Descriptions
***************************************

The error codes used throughout the library are described below.  The
return code 'GNUTLS_E_SUCCESS' indicates a successful operation, and is
guaranteed to have the value 0, so you can use it in logical
expressions.

0           GNUTLS_E_SUCCESS              Success.
-3          GNUTLS_E_UNKNOWN_COMPRESSION_ALGORITHMCould not negotiate a
                                          supported compression
                                          method.
-6          GNUTLS_E_UNKNOWN_CIPHER_TYPE  The cipher type is
                                          unsupported.
-7          GNUTLS_E_LARGE_PACKET         The transmitted packet is
                                          too large (EMSGSIZE).
-8          GNUTLS_E_UNSUPPORTED_VERSION_PACKETA packet with illegal or
                                          unsupported version was
                                          received.
-9          GNUTLS_E_UNEXPECTED_PACKET_LENGTHA TLS packet with
                                          unexpected length was
                                          received.
-10         GNUTLS_E_INVALID_SESSION      The specified session has
                                          been invalidated for some
                                          reason.
-12         GNUTLS_E_FATAL_ALERT_RECEIVED A TLS fatal alert has
                                          been received.
-15         GNUTLS_E_UNEXPECTED_PACKET    An unexpected TLS packet
                                          was received.
-16         GNUTLS_E_WARNING_ALERT_RECEIVEDA TLS warning alert has
                                          been received.
-18         GNUTLS_E_ERROR_IN_FINISHED_PACKETAn error was encountered
                                          at the TLS Finished
                                          packet calculation.
-19         GNUTLS_E_UNEXPECTED_HANDSHAKE_PACKETAn unexpected TLS
                                          handshake packet was
                                          received.
-21         GNUTLS_E_UNKNOWN_CIPHER_SUITE Could not negotiate a
                                          supported cipher suite.
-22         GNUTLS_E_UNWANTED_ALGORITHM   An algorithm that is not
                                          enabled was negotiated.
-23         GNUTLS_E_MPI_SCAN_FAILED      The scanning of a large
                                          integer has failed.
-24         GNUTLS_E_DECRYPTION_FAILED    Decryption has failed.
-25         GNUTLS_E_MEMORY_ERROR         Internal error in memory
                                          allocation.
-26         GNUTLS_E_DECOMPRESSION_FAILED Decompression of the TLS
                                          record packet has failed.
-27         GNUTLS_E_COMPRESSION_FAILED   Compression of the TLS
                                          record packet has failed.
-28         GNUTLS_E_AGAIN                Resource temporarily
                                          unavailable, try again.
-29         GNUTLS_E_EXPIRED              The requested session has
                                          expired.
-30         GNUTLS_E_DB_ERROR             Error in Database
                                          backend.
-31         GNUTLS_E_SRP_PWD_ERROR        Error in password file.
-32         GNUTLS_E_INSUFFICIENT_CREDENTIALSInsufficient credentials
                                          for that request.
-33         GNUTLS_E_HASH_FAILED          Hashing has failed.
-34         GNUTLS_E_BASE64_DECODING_ERRORBase64 decoding error.
-35         GNUTLS_E_MPI_PRINT_FAILED     Could not export a large
                                          integer.
-37         GNUTLS_E_REHANDSHAKE          Rehandshake was requested
                                          by the peer.
-38         GNUTLS_E_GOT_APPLICATION_DATA TLS Application data were
                                          received, while expecting
                                          handshake data.
-39         GNUTLS_E_RECORD_LIMIT_REACHED The upper limit of record
                                          packet sequence numbers
                                          has been reached.  Wow!
-40         GNUTLS_E_ENCRYPTION_FAILED    Encryption has failed.
-43         GNUTLS_E_CERTIFICATE_ERROR    Error in the certificate.
-44         GNUTLS_E_PK_ENCRYPTION_FAILED Public key encryption has
                                          failed.
-45         GNUTLS_E_PK_DECRYPTION_FAILED Public key decryption has
                                          failed.
-46         GNUTLS_E_PK_SIGN_FAILED       Public key signing has
                                          failed.
-47         GNUTLS_E_X509_UNSUPPORTED_CRITICAL_EXTENSIONUnsupported critical
                                          extension in X.509
                                          certificate.
-48         GNUTLS_E_KEY_USAGE_VIOLATION  Key usage violation in
                                          certificate has been
                                          detected.
-49         GNUTLS_E_NO_CERTIFICATE_FOUND No certificate was found.
-50         GNUTLS_E_INVALID_REQUEST      The request is invalid.
-51         GNUTLS_E_SHORT_MEMORY_BUFFER  The given memory buffer
                                          is too short to hold
                                          parameters.
-52         GNUTLS_E_INTERRUPTED          Function was interrupted.
-53         GNUTLS_E_PUSH_ERROR           Error in the push
                                          function.
-54         GNUTLS_E_PULL_ERROR           Error in the pull
                                          function.
-55         GNUTLS_E_RECEIVED_ILLEGAL_PARAMETERAn illegal parameter has
                                          been received.
-56         GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLEThe requested data were
                                          not available.
-57         GNUTLS_E_PKCS1_WRONG_PAD      Wrong padding in PKCS1
                                          packet.
-58         GNUTLS_E_RECEIVED_ILLEGAL_EXTENSIONAn illegal TLS extension
                                          was received.
-59         GNUTLS_E_INTERNAL_ERROR       GnuTLS internal error.
-60         GNUTLS_E_CERTIFICATE_KEY_MISMATCHThe certificate and the
                                          given key do not match.
-61         GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPEThe certificate type is
                                          not supported.
-62         GNUTLS_E_X509_UNKNOWN_SAN     Unknown Subject
                                          Alternative name in X.509
                                          certificate.
-63         GNUTLS_E_DH_PRIME_UNACCEPTABLEThe Diffie-Hellman prime
                                          sent by the server is not
                                          acceptable (not long
                                          enough).
-64         GNUTLS_E_FILE_ERROR           Error while reading file.
-67         GNUTLS_E_ASN1_ELEMENT_NOT_FOUNDASN1 parser: Element was
                                          not found.
-68         GNUTLS_E_ASN1_IDENTIFIER_NOT_FOUNDASN1 parser: Identifier
                                          was not found
-69         GNUTLS_E_ASN1_DER_ERROR       ASN1 parser: Error in DER
                                          parsing.
-70         GNUTLS_E_ASN1_VALUE_NOT_FOUND ASN1 parser: Value was
                                          not found.
-71         GNUTLS_E_ASN1_GENERIC_ERROR   ASN1 parser: Generic
                                          parsing error.
-72         GNUTLS_E_ASN1_VALUE_NOT_VALID ASN1 parser: Value is not
                                          valid.
-73         GNUTLS_E_ASN1_TAG_ERROR       ASN1 parser: Error in
                                          TAG.
-74         GNUTLS_E_ASN1_TAG_IMPLICIT    ASN1 parser: error in
                                          implicit tag
-75         GNUTLS_E_ASN1_TYPE_ANY_ERROR  ASN1 parser: Error in
                                          type 'ANY'.
-76         GNUTLS_E_ASN1_SYNTAX_ERROR    ASN1 parser: Syntax
                                          error.
-77         GNUTLS_E_ASN1_DER_OVERFLOW    ASN1 parser: Overflow in
                                          DER parsing.
-78         GNUTLS_E_TOO_MANY_EMPTY_PACKETSToo many empty record
                                          packets have been
                                          received.
-79         GNUTLS_E_OPENPGP_UID_REVOKED  The OpenPGP User ID is
                                          revoked.
-80         GNUTLS_E_UNKNOWN_PK_ALGORITHM An unknown public key
                                          algorithm was
                                          encountered.
-81         GNUTLS_E_TOO_MANY_HANDSHAKE_PACKETSToo many handshake
                                          packets have been
                                          received.
-84         GNUTLS_E_NO_TEMPORARY_RSA_PARAMSNo temporary RSA
                                          parameters were found.
-86         GNUTLS_E_NO_COMPRESSION_ALGORITHMSNo supported compression
                                          algorithms have been
                                          found.
-87         GNUTLS_E_NO_CIPHER_SUITES     No supported cipher
                                          suites have been found.
-88         GNUTLS_E_OPENPGP_GETKEY_FAILEDCould not get OpenPGP
                                          key.
-89         GNUTLS_E_PK_SIG_VERIFY_FAILED Public key signature
                                          verification has failed.
-90         GNUTLS_E_ILLEGAL_SRP_USERNAME The SRP username supplied
                                          is illegal.
-91         GNUTLS_E_SRP_PWD_PARSING_ERRORParsing error in password
                                          file.
-93         GNUTLS_E_NO_TEMPORARY_DH_PARAMSNo temporary DH
                                          parameters were found.
-94         GNUTLS_E_OPENPGP_FINGERPRINT_UNSUPPORTEDThe OpenPGP fingerprint
                                          is not supported.
-95         GNUTLS_E_X509_UNSUPPORTED_ATTRIBUTEThe certificate has
                                          unsupported attributes.
-96         GNUTLS_E_UNKNOWN_HASH_ALGORITHMThe hash algorithm is
                                          unknown.
-97         GNUTLS_E_UNKNOWN_PKCS_CONTENT_TYPEThe PKCS structure's
                                          content type is unknown.
-98         GNUTLS_E_UNKNOWN_PKCS_BAG_TYPEThe PKCS structure's bag
                                          type is unknown.
-99         GNUTLS_E_INVALID_PASSWORD     The given password
                                          contains invalid
                                          characters.
-100        GNUTLS_E_MAC_VERIFY_FAILED    The Message
                                          Authentication Code
                                          verification failed.
-101        GNUTLS_E_CONSTRAINT_ERROR     Some constraint limits
                                          were reached.
-104        GNUTLS_E_IA_VERIFY_FAILED     Verifying TLS/IA phase
                                          checksum failed
-105        GNUTLS_E_UNKNOWN_ALGORITHM    The specified algorithm
                                          or protocol is unknown.
-106        GNUTLS_E_UNSUPPORTED_SIGNATURE_ALGORITHMThe signature algorithm
                                          is not supported.
-107        GNUTLS_E_SAFE_RENEGOTIATION_FAILEDSafe renegotiation
                                          failed.
-108        GNUTLS_E_UNSAFE_RENEGOTIATION_DENIEDUnsafe renegotiation
                                          denied.
-109        GNUTLS_E_UNKNOWN_SRP_USERNAME The SRP username supplied
                                          is unknown.
-110        GNUTLS_E_PREMATURE_TERMINATIONThe TLS connection was
                                          non-properly terminated.
-201        GNUTLS_E_BASE64_ENCODING_ERRORBase64 encoding error.
-202        GNUTLS_E_INCOMPATIBLE_GCRYPT_LIBRARYThe crypto library
                                          version is too old.
-203        GNUTLS_E_INCOMPATIBLE_LIBTASN1_LIBRARYThe tasn1 library version
                                          is too old.
-204        GNUTLS_E_OPENPGP_KEYRING_ERRORError loading the
                                          keyring.
-205        GNUTLS_E_X509_UNSUPPORTED_OID The OID is not supported.
-206        GNUTLS_E_RANDOM_FAILED        Failed to acquire random
                                          data.
-207        GNUTLS_E_BASE64_UNEXPECTED_HEADER_ERRORBase64 unexpected header
                                          error.
-208        GNUTLS_E_OPENPGP_SUBKEY_ERROR Could not find OpenPGP
                                          subkey.
-209        GNUTLS_E_CRYPTO_ALREADY_REGISTEREDThere is already a crypto
                                          algorithm with lower
                                          priority.
-210        GNUTLS_E_HANDSHAKE_TOO_LARGE  The handshake data size
                                          is too large.
-211        GNUTLS_E_CRYPTODEV_IOCTL_ERRORError interfacing with
                                          /dev/crypto
-212        GNUTLS_E_CRYPTODEV_DEVICE_ERRORError opening /dev/crypto
-213        GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLEChannel binding data not
                                          available
-214        GNUTLS_E_BAD_COOKIE           The cookie was bad.
-215        GNUTLS_E_OPENPGP_PREFERRED_KEY_ERRORThe OpenPGP key has not a
                                          preferred key set.
-216        GNUTLS_E_INCOMPAT_DSA_KEY_WITH_TLS_PROTOCOLThe given DSA key is
                                          incompatible with the
                                          selected TLS protocol.
-292        GNUTLS_E_HEARTBEAT_PONG_RECEIVEDA heartbeat pong message
                                          was received.
-293        GNUTLS_E_HEARTBEAT_PING_RECEIVEDA heartbeat ping message
                                          was received.
-300        GNUTLS_E_PKCS11_ERROR         PKCS #11 error.
-301        GNUTLS_E_PKCS11_LOAD_ERROR    PKCS #11 initialization
                                          error.
-302        GNUTLS_E_PARSING_ERROR        Error in parsing.
-303        GNUTLS_E_PKCS11_PIN_ERROR     Error in provided PIN.
-305        GNUTLS_E_PKCS11_SLOT_ERROR    PKCS #11 error in slot
-306        GNUTLS_E_LOCKING_ERROR        Thread locking error
-307        GNUTLS_E_PKCS11_ATTRIBUTE_ERRORPKCS #11 error in
                                          attribute
-308        GNUTLS_E_PKCS11_DEVICE_ERROR  PKCS #11 error in device
-309        GNUTLS_E_PKCS11_DATA_ERROR    PKCS #11 error in data
-310        GNUTLS_E_PKCS11_UNSUPPORTED_FEATURE_ERRORPKCS #11 unsupported
                                          feature
-311        GNUTLS_E_PKCS11_KEY_ERROR     PKCS #11 error in key
-312        GNUTLS_E_PKCS11_PIN_EXPIRED   PKCS #11 PIN expired
-313        GNUTLS_E_PKCS11_PIN_LOCKED    PKCS #11 PIN locked
-314        GNUTLS_E_PKCS11_SESSION_ERROR PKCS #11 error in session
-315        GNUTLS_E_PKCS11_SIGNATURE_ERRORPKCS #11 error in
                                          signature
-316        GNUTLS_E_PKCS11_TOKEN_ERROR   PKCS #11 error in token
-317        GNUTLS_E_PKCS11_USER_ERROR    PKCS #11 user error
-318        GNUTLS_E_CRYPTO_INIT_FAILED   The initialization of
                                          crypto backend has
                                          failed.
-319        GNUTLS_E_TIMEDOUT             The operation timed out
-320        GNUTLS_E_USER_ERROR           The operation was
                                          cancelled due to user
                                          error
-321        GNUTLS_E_ECC_NO_SUPPORTED_CURVESNo supported ECC curves
                                          were found
-322        GNUTLS_E_ECC_UNSUPPORTED_CURVEThe curve is unsupported
-323        GNUTLS_E_PKCS11_REQUESTED_OBJECT_NOT_AVAILBLEThe requested PKCS #11
                                          object is not available
-324        GNUTLS_E_CERTIFICATE_LIST_UNSORTEDThe provided X.509
                                          certificate list is not
                                          sorted (in subject to
                                          issuer order)
-325        GNUTLS_E_ILLEGAL_PARAMETER    An illegal parameter was
                                          found.
-326        GNUTLS_E_NO_PRIORITIES_WERE_SETNo or insufficient
                                          priorities were set.
-327        GNUTLS_E_X509_UNSUPPORTED_EXTENSIONUnsupported extension in
                                          X.509 certificate.
-328        GNUTLS_E_SESSION_EOF          Peer has terminated the
                                          connection
-329        GNUTLS_E_TPM_ERROR            TPM error.
-330        GNUTLS_E_TPM_KEY_PASSWORD_ERRORError in provided
                                          password for key to be
                                          loaded in TPM.
-331        GNUTLS_E_TPM_SRK_PASSWORD_ERRORError in provided SRK
                                          password for TPM.
-332        GNUTLS_E_TPM_SESSION_ERROR    Cannot initialize a
                                          session with the TPM.
-333        GNUTLS_E_TPM_KEY_NOT_FOUND    TPM key was not found in
                                          persistent storage.
-334        GNUTLS_E_TPM_UNINITIALIZED    TPM is not initialized.
-335        GNUTLS_E_TPM_NO_LIB           The TPM library
                                          (trousers) cannot be
                                          found.
-340        GNUTLS_E_NO_CERTIFICATE_STATUSThere is no certificate
                                          status (OCSP).
-341        GNUTLS_E_OCSP_RESPONSE_ERROR  The OCSP response is
                                          invalid
-342        GNUTLS_E_RANDOM_DEVICE_ERROR  Error in the system's
                                          randomness device.
-343        GNUTLS_E_AUTH_ERROR           Could not authenticate
                                          peer.
-344        GNUTLS_E_NO_APPLICATION_PROTOCOLNo common application
                                          protocol could be
                                          negotiated.
-345        GNUTLS_E_SOCKETS_INIT_ERROR   Error in sockets
                                          initialization.
-400        GNUTLS_E_SELF_TEST_ERROR      Error while performing
                                          self checks.
-401        GNUTLS_E_NO_SELF_TEST         There is no self test for
                                          this algorithm.
-402        GNUTLS_E_LIB_IN_ERROR_STATE   An error has been
                                          detected in the library
                                          and cannot continue
                                          operations.
-403        GNUTLS_E_PK_GENERATION_ERROR  Error in public key
                                          generation.


File: gnutls.info,  Node: Supported ciphersuites,  Next: API reference,  Prev: Error codes,  Up: Top

Appendix D Supported Ciphersuites
*********************************

Ciphersuites
============

Ciphersuite name                            TLS ID         Since
--------------------------------------------------------------------------
TLS_RSA_NULL_MD5                            0x00 0x01      SSL3.0
TLS_RSA_NULL_SHA1                           0x00 0x02      SSL3.0
TLS_RSA_NULL_SHA256                         0x00 0x3B      TLS1.2
TLS_RSA_ARCFOUR_128_SHA1                    0x00 0x05      SSL3.0
TLS_RSA_ARCFOUR_128_MD5                     0x00 0x04      SSL3.0
TLS_RSA_3DES_EDE_CBC_SHA1                   0x00 0x0A      SSL3.0
TLS_RSA_AES_128_CBC_SHA1                    0x00 0x2F      SSL3.0
TLS_RSA_AES_256_CBC_SHA1                    0x00 0x35      SSL3.0
TLS_RSA_CAMELLIA_128_CBC_SHA256             0x00 0xBA      TLS1.2
TLS_RSA_CAMELLIA_256_CBC_SHA256             0x00 0xC0      TLS1.2
TLS_RSA_CAMELLIA_128_CBC_SHA1               0x00 0x41      SSL3.0
TLS_RSA_CAMELLIA_256_CBC_SHA1               0x00 0x84      SSL3.0
TLS_RSA_AES_128_CBC_SHA256                  0x00 0x3C      TLS1.2
TLS_RSA_AES_256_CBC_SHA256                  0x00 0x3D      TLS1.2
TLS_RSA_AES_128_GCM_SHA256                  0x00 0x9C      TLS1.2
TLS_RSA_AES_256_GCM_SHA384                  0x00 0x9D      TLS1.2
TLS_RSA_CAMELLIA_128_GCM_SHA256             0xC0 0x7A      TLS1.2
TLS_RSA_CAMELLIA_256_GCM_SHA384             0xC0 0x7B      TLS1.2
TLS_RSA_SALSA20_256_SHA1                    0xE4 0x11      SSL3.0
TLS_RSA_ESTREAM_SALSA20_256_SHA1            0xE4 0x10      SSL3.0
TLS_DHE_DSS_ARCFOUR_128_SHA1                0x00 0x66      SSL3.0
TLS_DHE_DSS_3DES_EDE_CBC_SHA1               0x00 0x13      SSL3.0
TLS_DHE_DSS_AES_128_CBC_SHA1                0x00 0x32      SSL3.0
TLS_DHE_DSS_AES_256_CBC_SHA1                0x00 0x38      SSL3.0
TLS_DHE_DSS_CAMELLIA_128_CBC_SHA256         0x00 0xBD      TLS1.2
TLS_DHE_DSS_CAMELLIA_256_CBC_SHA256         0x00 0xC3      TLS1.2
TLS_DHE_DSS_CAMELLIA_128_CBC_SHA1           0x00 0x44      SSL3.0
TLS_DHE_DSS_CAMELLIA_256_CBC_SHA1           0x00 0x87      SSL3.0
TLS_DHE_DSS_AES_128_CBC_SHA256              0x00 0x40      TLS1.2
TLS_DHE_DSS_AES_256_CBC_SHA256              0x00 0x6A      TLS1.2
TLS_DHE_DSS_AES_128_GCM_SHA256              0x00 0xA2      TLS1.2
TLS_DHE_DSS_AES_256_GCM_SHA384              0x00 0xA3      TLS1.2
TLS_DHE_DSS_CAMELLIA_128_GCM_SHA256         0xC0 0x80      TLS1.2
TLS_DHE_DSS_CAMELLIA_256_GCM_SHA384         0xC0 0x81      TLS1.2
TLS_DHE_RSA_3DES_EDE_CBC_SHA1               0x00 0x16      SSL3.0
TLS_DHE_RSA_AES_128_CBC_SHA1                0x00 0x33      SSL3.0
TLS_DHE_RSA_AES_256_CBC_SHA1                0x00 0x39      SSL3.0
TLS_DHE_RSA_CAMELLIA_128_CBC_SHA256         0x00 0xBE      TLS1.2
TLS_DHE_RSA_CAMELLIA_256_CBC_SHA256         0x00 0xC4      TLS1.2
TLS_DHE_RSA_CAMELLIA_128_CBC_SHA1           0x00 0x45      SSL3.0
TLS_DHE_RSA_CAMELLIA_256_CBC_SHA1           0x00 0x88      SSL3.0
TLS_DHE_RSA_AES_128_CBC_SHA256              0x00 0x67      TLS1.2
TLS_DHE_RSA_AES_256_CBC_SHA256              0x00 0x6B      TLS1.2
TLS_DHE_RSA_AES_128_GCM_SHA256              0x00 0x9E      TLS1.2
TLS_DHE_RSA_AES_256_GCM_SHA384              0x00 0x9F      TLS1.2
TLS_DHE_RSA_CAMELLIA_128_GCM_SHA256         0xC0 0x7C      TLS1.2
TLS_DHE_RSA_CAMELLIA_256_GCM_SHA384         0xC0 0x7D      TLS1.2
TLS_ECDHE_RSA_NULL_SHA1                     0xC0 0x10      SSL3.0
TLS_ECDHE_RSA_3DES_EDE_CBC_SHA1             0xC0 0x12      SSL3.0
TLS_ECDHE_RSA_AES_128_CBC_SHA1              0xC0 0x13      SSL3.0
TLS_ECDHE_RSA_AES_256_CBC_SHA1              0xC0 0x14      SSL3.0
TLS_ECDHE_RSA_AES_256_CBC_SHA384            0xC0 0x28      TLS1.2
TLS_ECDHE_RSA_ARCFOUR_128_SHA1              0xC0 0x11      SSL3.0
TLS_ECDHE_RSA_CAMELLIA_128_CBC_SHA256       0xC0 0x76      TLS1.2
TLS_ECDHE_RSA_CAMELLIA_256_CBC_SHA384       0xC0 0x77      TLS1.2
TLS_ECDHE_ECDSA_NULL_SHA1                   0xC0 0x06      SSL3.0
TLS_ECDHE_ECDSA_3DES_EDE_CBC_SHA1           0xC0 0x08      SSL3.0
TLS_ECDHE_ECDSA_AES_128_CBC_SHA1            0xC0 0x09      SSL3.0
TLS_ECDHE_ECDSA_AES_256_CBC_SHA1            0xC0 0x0A      SSL3.0
TLS_ECDHE_ECDSA_ARCFOUR_128_SHA1            0xC0 0x07      SSL3.0
TLS_ECDHE_ECDSA_CAMELLIA_128_CBC_SHA256     0xC0 0x72      TLS1.2
TLS_ECDHE_ECDSA_CAMELLIA_256_CBC_SHA384     0xC0 0x73      TLS1.2
TLS_ECDHE_ECDSA_AES_128_CBC_SHA256          0xC0 0x23      TLS1.2
TLS_ECDHE_RSA_AES_128_CBC_SHA256            0xC0 0x27      TLS1.2
TLS_ECDHE_ECDSA_CAMELLIA_128_GCM_SHA256     0xC0 0x86      TLS1.2
TLS_ECDHE_ECDSA_CAMELLIA_256_GCM_SHA384     0xC0 0x87      TLS1.2
TLS_ECDHE_ECDSA_AES_128_GCM_SHA256          0xC0 0x2B      TLS1.2
TLS_ECDHE_ECDSA_AES_256_GCM_SHA384          0xC0 0x2C      TLS1.2
TLS_ECDHE_RSA_AES_128_GCM_SHA256            0xC0 0x2F      TLS1.2
TLS_ECDHE_RSA_AES_256_GCM_SHA384            0xC0 0x30      TLS1.2
TLS_ECDHE_ECDSA_AES_256_CBC_SHA384          0xC0 0x24      TLS1.2
TLS_ECDHE_RSA_CAMELLIA_128_GCM_SHA256       0xC0 0x8A      TLS1.2
TLS_ECDHE_RSA_CAMELLIA_256_GCM_SHA384       0xC0 0x8B      TLS1.2
TLS_ECDHE_RSA_SALSA20_256_SHA1              0xE4 0x13      SSL3.0
TLS_ECDHE_ECDSA_SALSA20_256_SHA1            0xE4 0x15      SSL3.0
TLS_ECDHE_RSA_ESTREAM_SALSA20_256_SHA1      0xE4 0x12      SSL3.0
TLS_ECDHE_ECDSA_ESTREAM_SALSA20_256_SHA1    0xE4 0x14      SSL3.0
TLS_ECDHE_PSK_3DES_EDE_CBC_SHA1             0xC0 0x34      SSL3.0
TLS_ECDHE_PSK_AES_128_CBC_SHA1              0xC0 0x35      SSL3.0
TLS_ECDHE_PSK_AES_256_CBC_SHA1              0xC0 0x36      SSL3.0
TLS_ECDHE_PSK_AES_128_CBC_SHA256            0xC0 0x37      TLS1.2
TLS_ECDHE_PSK_AES_256_CBC_SHA384            0xC0 0x38      TLS1.2
TLS_ECDHE_PSK_ARCFOUR_128_SHA1              0xC0 0x33      SSL3.0
TLS_ECDHE_PSK_NULL_SHA1                     0xC0 0x39      SSL3.0
TLS_ECDHE_PSK_NULL_SHA256                   0xC0 0x3A      TLS1.2
TLS_ECDHE_PSK_NULL_SHA384                   0xC0 0x3B      TLS1.0
TLS_ECDHE_PSK_CAMELLIA_128_CBC_SHA256       0xC0 0x9A      TLS1.2
TLS_ECDHE_PSK_CAMELLIA_256_CBC_SHA384       0xC0 0x9B      TLS1.2
TLS_ECDHE_PSK_SALSA20_256_SHA1              0xE4 0x19      SSL3.0
TLS_ECDHE_PSK_ESTREAM_SALSA20_256_SHA1      0xE4 0x18      SSL3.0
TLS_PSK_ARCFOUR_128_SHA1                    0x00 0x8A      SSL3.0
TLS_PSK_3DES_EDE_CBC_SHA1                   0x00 0x8B      SSL3.0
TLS_PSK_AES_128_CBC_SHA1                    0x00 0x8C      SSL3.0
TLS_PSK_AES_256_CBC_SHA1                    0x00 0x8D      SSL3.0
TLS_PSK_AES_128_CBC_SHA256                  0x00 0xAE      TLS1.2
TLS_PSK_AES_256_GCM_SHA384                  0x00 0xA9      TLS1.2
TLS_PSK_CAMELLIA_128_GCM_SHA256             0xC0 0x8E      TLS1.2
TLS_PSK_CAMELLIA_256_GCM_SHA384             0xC0 0x8F      TLS1.2
TLS_PSK_AES_128_GCM_SHA256                  0x00 0xA8      TLS1.2
TLS_PSK_NULL_SHA1                           0x00 0x2C      SSL3.0
TLS_PSK_NULL_SHA256                         0x00 0xB0      TLS1.2
TLS_PSK_CAMELLIA_128_CBC_SHA256             0xC0 0x94      TLS1.2
TLS_PSK_CAMELLIA_256_CBC_SHA384             0xC0 0x95      TLS1.2
TLS_PSK_SALSA20_256_SHA1                    0xE4 0x17      SSL3.0
TLS_PSK_ESTREAM_SALSA20_256_SHA1            0xE4 0x16      SSL3.0
TLS_PSK_AES_256_CBC_SHA384                  0x00 0xAF      TLS1.2
TLS_PSK_NULL_SHA384                         0x00 0xB1      TLS1.2
TLS_RSA_PSK_ARCFOUR_128_SHA1                0x00 0x92      TLS1.0
TLS_RSA_PSK_3DES_EDE_CBC_SHA1               0x00 0x93      TLS1.0
TLS_RSA_PSK_AES_128_CBC_SHA1                0x00 0x94      TLS1.0
TLS_RSA_PSK_AES_256_CBC_SHA1                0x00 0x95      TLS1.0
TLS_RSA_PSK_CAMELLIA_128_GCM_SHA256         0xC0 0x92      TLS1.2
TLS_RSA_PSK_CAMELLIA_256_GCM_SHA384         0xC0 0x93      TLS1.2
TLS_RSA_PSK_AES_128_GCM_SHA256              0x00 0xAC      TLS1.2
TLS_RSA_PSK_AES_128_CBC_SHA256              0x00 0xB6      TLS1.2
TLS_RSA_PSK_NULL_SHA1                       0x00 0x2E      TLS1.0
TLS_RSA_PSK_NULL_SHA256                     0x00 0xB8      TLS1.2
TLS_RSA_PSK_AES_256_GCM_SHA384              0x00 0xAD      TLS1.2
TLS_RSA_PSK_AES_256_CBC_SHA384              0x00 0xB7      TLS1.2
TLS_RSA_PSK_NULL_SHA384                     0x00 0xB9      TLS1.2
TLS_RSA_PSK_CAMELLIA_128_CBC_SHA256         0xC0 0x98      TLS1.2
TLS_RSA_PSK_CAMELLIA_256_CBC_SHA384         0xC0 0x99      TLS1.2
TLS_DHE_PSK_ARCFOUR_128_SHA1                0x00 0x8E      SSL3.0
TLS_DHE_PSK_3DES_EDE_CBC_SHA1               0x00 0x8F      SSL3.0
TLS_DHE_PSK_AES_128_CBC_SHA1                0x00 0x90      SSL3.0
TLS_DHE_PSK_AES_256_CBC_SHA1                0x00 0x91      SSL3.0
TLS_DHE_PSK_AES_128_CBC_SHA256              0x00 0xB2      TLS1.2
TLS_DHE_PSK_AES_128_GCM_SHA256              0x00 0xAA      TLS1.2
TLS_DHE_PSK_NULL_SHA1                       0x00 0x2D      SSL3.0
TLS_DHE_PSK_NULL_SHA256                     0x00 0xB4      TLS1.2
TLS_DHE_PSK_NULL_SHA384                     0x00 0xB5      TLS1.2
TLS_DHE_PSK_AES_256_CBC_SHA384              0x00 0xB3      TLS1.2
TLS_DHE_PSK_AES_256_GCM_SHA384              0x00 0xAB      TLS1.2
TLS_DHE_PSK_CAMELLIA_128_CBC_SHA256         0xC0 0x96      TLS1.2
TLS_DHE_PSK_CAMELLIA_256_CBC_SHA384         0xC0 0x97      TLS1.2
TLS_DHE_PSK_CAMELLIA_128_GCM_SHA256         0xC0 0x90      TLS1.2
TLS_DHE_PSK_CAMELLIA_256_GCM_SHA384         0xC0 0x91      TLS1.2
TLS_DH_ANON_ARCFOUR_128_MD5                 0x00 0x18      SSL3.0
TLS_DH_ANON_3DES_EDE_CBC_SHA1               0x00 0x1B      SSL3.0
TLS_DH_ANON_AES_128_CBC_SHA1                0x00 0x34      SSL3.0
TLS_DH_ANON_AES_256_CBC_SHA1                0x00 0x3A      SSL3.0
TLS_DH_ANON_CAMELLIA_128_CBC_SHA256         0x00 0xBF      TLS1.2
TLS_DH_ANON_CAMELLIA_256_CBC_SHA256         0x00 0xC5      TLS1.2
TLS_DH_ANON_CAMELLIA_128_CBC_SHA1           0x00 0x46      SSL3.0
TLS_DH_ANON_CAMELLIA_256_CBC_SHA1           0x00 0x89      SSL3.0
TLS_DH_ANON_AES_128_CBC_SHA256              0x00 0x6C      TLS1.2
TLS_DH_ANON_AES_256_CBC_SHA256              0x00 0x6D      TLS1.2
TLS_DH_ANON_AES_128_GCM_SHA256              0x00 0xA6      TLS1.2
TLS_DH_ANON_AES_256_GCM_SHA384              0x00 0xA7      TLS1.2
TLS_DH_ANON_CAMELLIA_128_GCM_SHA256         0xC0 0x84      TLS1.2
TLS_DH_ANON_CAMELLIA_256_GCM_SHA384         0xC0 0x85      TLS1.2
TLS_ECDH_ANON_NULL_SHA1                     0xC0 0x15      SSL3.0
TLS_ECDH_ANON_3DES_EDE_CBC_SHA1             0xC0 0x17      SSL3.0
TLS_ECDH_ANON_AES_128_CBC_SHA1              0xC0 0x18      SSL3.0
TLS_ECDH_ANON_AES_256_CBC_SHA1              0xC0 0x19      SSL3.0
TLS_ECDH_ANON_ARCFOUR_128_SHA1              0xC0 0x16      SSL3.0
TLS_SRP_SHA_3DES_EDE_CBC_SHA1               0xC0 0x1A      SSL3.0
TLS_SRP_SHA_AES_128_CBC_SHA1                0xC0 0x1D      SSL3.0
TLS_SRP_SHA_AES_256_CBC_SHA1                0xC0 0x20      SSL3.0
TLS_SRP_SHA_DSS_3DES_EDE_CBC_SHA1           0xC0 0x1C      SSL3.0
TLS_SRP_SHA_RSA_3DES_EDE_CBC_SHA1           0xC0 0x1B      SSL3.0
TLS_SRP_SHA_DSS_AES_128_CBC_SHA1            0xC0 0x1F      SSL3.0
TLS_SRP_SHA_RSA_AES_128_CBC_SHA1            0xC0 0x1E      SSL3.0
TLS_SRP_SHA_DSS_AES_256_CBC_SHA1            0xC0 0x22      SSL3.0
TLS_SRP_SHA_RSA_AES_256_CBC_SHA1            0xC0 0x21      SSL3.0

Certificate types
=================

'X.509'
'OPENPGP'

Protocols
=========

'SSL3.0'
'TLS1.0'
'TLS1.1'
'TLS1.2'
'DTLS0.9'
'DTLS1.0'
'DTLS1.2'

Ciphers
=======

'AES-256-CBC'
'AES-192-CBC'
'AES-128-CBC'
'AES-128-GCM'
'AES-256-GCM'
'ARCFOUR-128'
'ESTREAM-SALSA20-256'
'SALSA20-256'
'CAMELLIA-256-CBC'
'CAMELLIA-192-CBC'
'CAMELLIA-128-CBC'
'CAMELLIA-128-GCM'
'CAMELLIA-256-GCM'
'3DES-CBC'
'DES-CBC'
'ARCFOUR-40'
'RC2-40'
'NULL'

MAC algorithms
==============

'SHA1'
'MD5'
'SHA256'
'SHA384'
'SHA512'
'SHA224'
'UMAC-96'
'UMAC-128'
'AEAD'

Key exchange methods
====================

'ANON-DH'
'ANON-ECDH'
'RSA'
'DHE-RSA'
'DHE-DSS'
'ECDHE-RSA'
'ECDHE-ECDSA'
'SRP-DSS'
'SRP-RSA'
'SRP'
'PSK'
'RSA-PSK'
'DHE-PSK'
'ECDHE-PSK'
'RSA-EXPORT'

Public key algorithms
=====================

'RSA'
'DSA'
'EC'

Public key signature algorithms
===============================

'RSA-SHA1'
'RSA-SHA1'
'RSA-SHA224'
'RSA-SHA256'
'RSA-SHA384'
'RSA-SHA512'
'RSA-RMD160'
'DSA-SHA1'
'DSA-SHA1'
'DSA-SHA224'
'DSA-SHA256'
'RSA-MD5'
'RSA-MD5'
'RSA-MD2'
'ECDSA-SHA1'
'ECDSA-SHA224'
'ECDSA-SHA256'
'ECDSA-SHA384'
'ECDSA-SHA512'

Elliptic curves
===============

'SECP192R1'
'SECP224R1'
'SECP256R1'
'SECP384R1'
'SECP521R1'

Compression methods
===================

'DEFLATE'
'NULL'


File: gnutls.info,  Node: API reference,  Next: Copying Information,  Prev: Supported ciphersuites,  Up: Top

Appendix E API reference
************************

* Menu:

* Core TLS API::
* Datagram TLS API::
* X509 certificate API::
* OCSP API::
* OpenPGP API::
* PKCS 12 API::
* PKCS 11 API::
* TPM API::
* Abstract key API::
* DANE API::
* Cryptographic API::
* Compatibility API::


File: gnutls.info,  Node: Core TLS API,  Next: Datagram TLS API,  Up: API reference

E.1 Core TLS API
================

The prototypes for the following functions lie in 'gnutls/gnutls.h'.

gnutls_alert_get
----------------

 -- Function: gnutls_alert_description_t gnutls_alert_get
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function will return the last alert number received.  This
     function should be called when 'GNUTLS_E_WARNING_ALERT_RECEIVED' or
     'GNUTLS_E_FATAL_ALERT_RECEIVED' errors are returned by a gnutls
     function.  The peer may send alerts if he encounters an error.  If
     no alert has been received the returned value is undefined.

     *Returns:* the last alert received, a 'gnutls_alert_description_t'
     value.

gnutls_alert_get_name
---------------------

 -- Function: const char * gnutls_alert_get_name
          (gnutls_alert_description_t ALERT)
     ALERT: is an alert number.

     This function will return a string that describes the given alert
     number, or 'NULL' .  See 'gnutls_alert_get()' .

     *Returns:* string corresponding to 'gnutls_alert_description_t'
     value.

gnutls_alert_get_strname
------------------------

 -- Function: const char * gnutls_alert_get_strname
          (gnutls_alert_description_t ALERT)
     ALERT: is an alert number.

     This function will return a string of the name of the alert.

     *Returns:* string corresponding to 'gnutls_alert_description_t'
     value.

     *Since:* 3.0

gnutls_alert_send
-----------------

 -- Function: int gnutls_alert_send (gnutls_session_t SESSION,
          gnutls_alert_level_t LEVEL, gnutls_alert_description_t DESC)
     SESSION: is a 'gnutls_session_t' structure.

     LEVEL: is the level of the alert

     DESC: is the alert description

     This function will send an alert to the peer in order to inform him
     of something important (eg.  his Certificate could not be
     verified).  If the alert level is Fatal then the peer is expected
     to close the connection, otherwise he may ignore the alert and
     continue.

     The error code of the underlying record send function will be
     returned, so you may also receive 'GNUTLS_E_INTERRUPTED' or
     'GNUTLS_E_AGAIN' as well.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_alert_send_appropriate
-----------------------------

 -- Function: int gnutls_alert_send_appropriate (gnutls_session_t
          SESSION, int ERR)
     SESSION: is a 'gnutls_session_t' structure.

     ERR: is an integer

     Sends an alert to the peer depending on the error code returned by
     a gnutls function.  This function will call
     'gnutls_error_to_alert()' to determine the appropriate alert to
     send.

     This function may also return 'GNUTLS_E_AGAIN' , or
     'GNUTLS_E_INTERRUPTED' .

     If the return value is 'GNUTLS_E_INVALID_REQUEST' , then no alert
     has been sent to the peer.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_alpn_get_selected_protocol
---------------------------------

 -- Function: int gnutls_alpn_get_selected_protocol (gnutls_session_t
          SESSION, gnutls_datum_t * PROTOCOL)
     SESSION: is a 'gnutls_session_t' structure.

     PROTOCOL: will hold the protocol name

     This function allows you to get the negotiated protocol name.  The
     returned protocol should be treated as opaque, constant value and
     only valid during the session life.

     The selected protocol is the first supported by the list sent by
     the client.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     Since 3.2.0

gnutls_alpn_set_protocols
-------------------------

 -- Function: int gnutls_alpn_set_protocols (gnutls_session_t SESSION,
          const gnutls_datum_t * PROTOCOLS, unsigned PROTOCOLS_SIZE,
          unsigned int FLAGS)
     SESSION: is a 'gnutls_session_t' structure.

     PROTOCOLS: is the protocol names to add.

     PROTOCOLS_SIZE: the number of protocols to add.

     FLAGS: zero or 'GNUTLS_ALPN_' *

     This function is to be used by both clients and servers, to declare
     the supported ALPN protocols, which are used during negotiation
     with peer.

     If 'GNUTLS_ALPN_MAND' is specified the connection will be aborted
     if no matching ALPN protocol is found.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     Since 3.2.0

gnutls_anon_allocate_client_credentials
---------------------------------------

 -- Function: int gnutls_anon_allocate_client_credentials
          (gnutls_anon_client_credentials_t * SC)
     SC: is a pointer to a 'gnutls_anon_client_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to allocate it.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_anon_allocate_server_credentials
---------------------------------------

 -- Function: int gnutls_anon_allocate_server_credentials
          (gnutls_anon_server_credentials_t * SC)
     SC: is a pointer to a 'gnutls_anon_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to allocate it.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_anon_free_client_credentials
-----------------------------------

 -- Function: void gnutls_anon_free_client_credentials
          (gnutls_anon_client_credentials_t SC)
     SC: is a 'gnutls_anon_client_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to free (deallocate) it.

gnutls_anon_free_server_credentials
-----------------------------------

 -- Function: void gnutls_anon_free_server_credentials
          (gnutls_anon_server_credentials_t SC)
     SC: is a 'gnutls_anon_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to free (deallocate) it.

gnutls_anon_set_params_function
-------------------------------

 -- Function: void gnutls_anon_set_params_function
          (gnutls_anon_server_credentials_t RES, gnutls_params_function
          * FUNC)
     RES: is a gnutls_anon_server_credentials_t structure

     FUNC: is the function to be called

     This function will set a callback in order for the server to get
     the Diffie-Hellman or RSA parameters for anonymous authentication.
     The callback should return 'GNUTLS_E_SUCCESS' (0) on success.

gnutls_anon_set_server_dh_params
--------------------------------

 -- Function: void gnutls_anon_set_server_dh_params
          (gnutls_anon_server_credentials_t RES, gnutls_dh_params_t
          DH_PARAMS)
     RES: is a gnutls_anon_server_credentials_t structure

     DH_PARAMS: is a structure that holds Diffie-Hellman parameters.

     This function will set the Diffie-Hellman parameters for an
     anonymous server to use.  These parameters will be used in
     Anonymous Diffie-Hellman cipher suites.

gnutls_anon_set_server_params_function
--------------------------------------

 -- Function: void gnutls_anon_set_server_params_function
          (gnutls_anon_server_credentials_t RES, gnutls_params_function
          * FUNC)
     RES: is a gnutls_certificate_credentials_t structure

     FUNC: is the function to be called

     This function will set a callback in order for the server to get
     the Diffie-Hellman parameters for anonymous authentication.  The
     callback should return 'GNUTLS_E_SUCCESS' (0) on success.

gnutls_auth_client_get_type
---------------------------

 -- Function: gnutls_credentials_type_t gnutls_auth_client_get_type
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Returns the type of credentials that were used for client
     authentication.  The returned information is to be used to
     distinguish the function used to access authentication data.

     *Returns:* The type of credentials for the client authentication
     schema, a 'gnutls_credentials_type_t' type.

gnutls_auth_get_type
--------------------

 -- Function: gnutls_credentials_type_t gnutls_auth_get_type
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Returns type of credentials for the current authentication schema.
     The returned information is to be used to distinguish the function
     used to access authentication data.

     Eg.  for CERTIFICATE ciphersuites (key exchange algorithms:
     'GNUTLS_KX_RSA' , 'GNUTLS_KX_DHE_RSA' ), the same function are to
     be used to access the authentication data.

     *Returns:* The type of credentials for the current authentication
     schema, a 'gnutls_credentials_type_t' type.

gnutls_auth_server_get_type
---------------------------

 -- Function: gnutls_credentials_type_t gnutls_auth_server_get_type
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Returns the type of credentials that were used for server
     authentication.  The returned information is to be used to
     distinguish the function used to access authentication data.

     *Returns:* The type of credentials for the server authentication
     schema, a 'gnutls_credentials_type_t' type.

gnutls_bye
----------

 -- Function: int gnutls_bye (gnutls_session_t SESSION,
          gnutls_close_request_t HOW)
     SESSION: is a 'gnutls_session_t' structure.

     HOW: is an integer

     Terminates the current TLS/SSL connection.  The connection should
     have been initiated using 'gnutls_handshake()' .  'how' should be
     one of 'GNUTLS_SHUT_RDWR' , 'GNUTLS_SHUT_WR' .

     In case of 'GNUTLS_SHUT_RDWR' the TLS session gets terminated and
     further receives and sends will be disallowed.  If the return value
     is zero you may continue using the underlying transport layer.
     'GNUTLS_SHUT_RDWR' sends an alert containing a close request and
     waits for the peer to reply with the same message.

     In case of 'GNUTLS_SHUT_WR' the TLS session gets terminated and
     further sends will be disallowed.  In order to reuse the connection
     you should wait for an EOF from the peer.  'GNUTLS_SHUT_WR' sends
     an alert containing a close request.

     Note that not all implementations will properly terminate a TLS
     connection.  Some of them, usually for performance reasons, will
     terminate only the underlying transport layer, and thus not
     distinguishing between a malicious party prematurely terminating
     the connection and normal termination.

     This function may also return 'GNUTLS_E_AGAIN' or
     'GNUTLS_E_INTERRUPTED' ; cf.  'gnutls_record_get_direction()' .

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code, see
     function documentation for entire semantics.

gnutls_certificate_activation_time_peers
----------------------------------------

 -- Function: time_t gnutls_certificate_activation_time_peers
          (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     This function will return the peer's certificate activation time.
     This is the creation time for openpgp keys.

     *Returns:* (time_t)-1 on error.

     *Deprecated:* 'gnutls_certificate_verify_peers2()' now verifies
     activation times.

gnutls_certificate_allocate_credentials
---------------------------------------

 -- Function: int gnutls_certificate_allocate_credentials
          (gnutls_certificate_credentials_t * RES)
     RES: is a pointer to a 'gnutls_certificate_credentials_t'
     structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to allocate it.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_certificate_client_get_request_status
--------------------------------------------

 -- Function: int gnutls_certificate_client_get_request_status
          (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     Get whether client certificate is requested or not.

     *Returns:* 0 if the peer (server) did not request client
     authentication or 1 otherwise.

gnutls_certificate_expiration_time_peers
----------------------------------------

 -- Function: time_t gnutls_certificate_expiration_time_peers
          (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     This function will return the peer's certificate expiration time.

     *Returns:* (time_t)-1 on error.

     *Deprecated:* 'gnutls_certificate_verify_peers2()' now verifies
     expiration times.

gnutls_certificate_free_ca_names
--------------------------------

 -- Function: void gnutls_certificate_free_ca_names
          (gnutls_certificate_credentials_t SC)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     This function will delete all the CA name in the given credentials.
     Clients may call this to save some memory since in client side the
     CA names are not used.  Servers might want to use this function if
     a large list of trusted CAs is present and sending the names of it
     would just consume bandwidth without providing information to
     client.

     CA names are used by servers to advertise the CAs they support to
     clients.

gnutls_certificate_free_cas
---------------------------

 -- Function: void gnutls_certificate_free_cas
          (gnutls_certificate_credentials_t SC)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     This function will delete all the CAs associated with the given
     credentials.  Servers that do not use
     'gnutls_certificate_verify_peers2()' may call this to save some
     memory.

gnutls_certificate_free_credentials
-----------------------------------

 -- Function: void gnutls_certificate_free_credentials
          (gnutls_certificate_credentials_t SC)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to free (deallocate) it.

     This function does not free any temporary parameters associated
     with this structure (ie RSA and DH parameters are not freed by this
     function).

gnutls_certificate_free_crls
----------------------------

 -- Function: void gnutls_certificate_free_crls
          (gnutls_certificate_credentials_t SC)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     This function will delete all the CRLs associated with the given
     credentials.

gnutls_certificate_free_keys
----------------------------

 -- Function: void gnutls_certificate_free_keys
          (gnutls_certificate_credentials_t SC)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     This function will delete all the keys and the certificates
     associated with the given credentials.  This function must not be
     called when a TLS negotiation that uses the credentials is in
     progress.

gnutls_certificate_get_crt_raw
------------------------------

 -- Function: int gnutls_certificate_get_crt_raw
          (gnutls_certificate_credentials_t SC, unsigned IDX1, unsigned
          IDX2, gnutls_datum_t * CERT)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     IDX1: the index of the certificate if multiple are present

     IDX2: the index in the certificate list.  Zero gives the server's
     certificate.

     CERT: Will hold the DER encoded certificate.

     This function will return the DER encoded certificate of the server
     or any other certificate on its certificate chain (based on 'idx2'
     ).  The returned data should be treated as constant and only
     accessible during the lifetime of 'sc' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  In case the indexes are out of
     bounds 'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Since:* 3.2.5

gnutls_certificate_get_issuer
-----------------------------

 -- Function: int gnutls_certificate_get_issuer
          (gnutls_certificate_credentials_t SC, gnutls_x509_crt_t CERT,
          gnutls_x509_crt_t * ISSUER, unsigned int FLAGS)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     CERT: is the certificate to find issuer for

     ISSUER: Will hold the issuer if any.  Should be treated as
     constant.

     FLAGS: Use zero or 'GNUTLS_TL_GET_COPY'

     This function will return the issuer of a given certificate.  As
     with 'gnutls_x509_trust_list_get_issuer()' this function requires
     the 'GNUTLS_TL_GET_COPY' flag in order to operate with PKCS '11'
     trust lists.  In that case the issuer must be freed using
     'gnutls_x509_crt_deinit()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0

gnutls_certificate_get_ours
---------------------------

 -- Function: const gnutls_datum_t * gnutls_certificate_get_ours
          (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     Gets the certificate as sent to the peer in the last handshake.
     The certificate is in raw (DER) format.  No certificate list is
     being returned.  Only the first certificate.

     *Returns:* a pointer to a 'gnutls_datum_t' containing our
     certificate, or 'NULL' in case of an error or if no certificate was
     used.

gnutls_certificate_get_peers
----------------------------

 -- Function: const gnutls_datum_t * gnutls_certificate_get_peers
          (gnutls_session_t SESSION, unsigned int * LIST_SIZE)
     SESSION: is a gnutls session

     LIST_SIZE: is the length of the certificate list (may be 'NULL' )

     Get the peer's raw certificate (chain) as sent by the peer.  These
     certificates are in raw format (DER encoded for X.509).  In case of
     a X.509 then a certificate list may be present.  The first
     certificate in the list is the peer's certificate, following the
     issuer's certificate, then the issuer's issuer etc.

     In case of OpenPGP keys a single key will be returned in raw
     format.

     *Returns:* a pointer to a 'gnutls_datum_t' containing the peer's
     certificates, or 'NULL' in case of an error or if no certificate
     was used.

gnutls_certificate_get_peers_subkey_id
--------------------------------------

 -- Function: int gnutls_certificate_get_peers_subkey_id
          (gnutls_session_t SESSION, gnutls_datum_t * ID)
     SESSION: is a gnutls session

     ID: will contain the ID

     Get the peer's subkey ID when OpenPGP certificates are used.  The
     returned 'id' should be treated as constant.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

     *Since:* 3.1.3

gnutls_certificate_send_x509_rdn_sequence
-----------------------------------------

 -- Function: void gnutls_certificate_send_x509_rdn_sequence
          (gnutls_session_t SESSION, int STATUS)
     SESSION: is a pointer to a 'gnutls_session_t' structure.

     STATUS: is 0 or 1

     If status is non zero, this function will order gnutls not to send
     the rdnSequence in the certificate request message.  That is the
     server will not advertise its trusted CAs to the peer.  If status
     is zero then the default behaviour will take effect, which is to
     advertise the server's trusted CAs.

     This function has no effect in clients, and in authentication
     methods other than certificate with X.509 certificates.

gnutls_certificate_server_set_request
-------------------------------------

 -- Function: void gnutls_certificate_server_set_request
          (gnutls_session_t SESSION, gnutls_certificate_request_t REQ)
     SESSION: is a 'gnutls_session_t' structure.

     REQ: is one of GNUTLS_CERT_REQUEST, GNUTLS_CERT_REQUIRE

     This function specifies if we (in case of a server) are going to
     send a certificate request message to the client.  If 'req' is
     GNUTLS_CERT_REQUIRE then the server will return an error if the
     peer does not provide a certificate.  If you do not call this
     function then the client will not be asked to send a certificate.

gnutls_certificate_set_dh_params
--------------------------------

 -- Function: void gnutls_certificate_set_dh_params
          (gnutls_certificate_credentials_t RES, gnutls_dh_params_t
          DH_PARAMS)
     RES: is a gnutls_certificate_credentials_t structure

     DH_PARAMS: is a structure that holds Diffie-Hellman parameters.

     This function will set the Diffie-Hellman parameters for a
     certificate server to use.  These parameters will be used in
     Ephemeral Diffie-Hellman cipher suites.  Note that only a pointer
     to the parameters are stored in the certificate handle, so you must
     not deallocate the parameters before the certificate is
     deallocated.

gnutls_certificate_set_ocsp_status_request_file
-----------------------------------------------

 -- Function: int gnutls_certificate_set_ocsp_status_request_file
          (gnutls_certificate_credentials_t SC, const char *
          RESPONSE_FILE, unsigned int FLAGS)
     SC: is a credentials structure.

     RESPONSE_FILE: a filename of the OCSP response

     FLAGS: should be zero

     This function sets the filename of an OCSP response, that will be
     sent to the client if requests an OCSP certificate status.  This is
     a convenience function which is inefficient on busy servers since
     the file is opened on every access.  Use
     'gnutls_certificate_set_ocsp_status_request_function()' to
     fine-tune file accesses.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     *Since:* 3.1.3

gnutls_certificate_set_ocsp_status_request_function
---------------------------------------------------

 -- Function: void gnutls_certificate_set_ocsp_status_request_function
          (gnutls_certificate_credentials_t SC,
          gnutls_status_request_ocsp_func OCSP_FUNC, void * PTR)
     SC: is a 'gnutls_certificate_credentials_t' structure.

     OCSP_FUNC: function pointer to OCSP status request callback.

     PTR: opaque pointer passed to callback function

     This function is to be used by server to register a callback to
     handle OCSP status requests from the client.  The callback will be
     invoked if the client supplied a status-request OCSP extension.
     The callback function prototype is:

     typedef int (*gnutls_status_request_ocsp_func) (gnutls_session_t
     session, void *ptr, gnutls_datum_t *ocsp_response);

     The callback will be invoked if the client requests an OCSP
     certificate status.  The callback may return
     'GNUTLS_E_NO_CERTIFICATE_STATUS' , if there is no recent OCSP
     response.  If the callback returns 'GNUTLS_E_SUCCESS' , the server
     will provide the client with the ocsp_response.

     The response must be a value allocated using 'gnutls_malloc()' ,
     and will be deinitialized when needed.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     *Since:* 3.1.3

gnutls_certificate_set_params_function
--------------------------------------

 -- Function: void gnutls_certificate_set_params_function
          (gnutls_certificate_credentials_t RES, gnutls_params_function
          * FUNC)
     RES: is a gnutls_certificate_credentials_t structure

     FUNC: is the function to be called

     This function will set a callback in order for the server to get
     the Diffie-Hellman or RSA parameters for certificate
     authentication.  The callback should return 'GNUTLS_E_SUCCESS' (0)
     on success.

gnutls_certificate_set_pin_function
-----------------------------------

 -- Function: void gnutls_certificate_set_pin_function
          (gnutls_certificate_credentials_t CRED, gnutls_pin_callback_t
          FN, void * USERDATA)
     CRED: is a 'gnutls_certificate_credentials_t' structure.

     FN: A PIN callback

     USERDATA: Data to be passed in the callback

     This function will set a callback function to be used when required
     to access a protected object.  This function overrides any other
     global PIN functions.

     Note that this function must be called right after initialization
     to have effect.

     *Since:* 3.1.0

gnutls_certificate_set_retrieve_function
----------------------------------------

 -- Function: void gnutls_certificate_set_retrieve_function
          (gnutls_certificate_credentials_t CRED,
          gnutls_certificate_retrieve_function * FUNC)
     CRED: is a 'gnutls_certificate_credentials_t' structure.

     FUNC: is the callback function

     This function sets a callback to be called in order to retrieve the
     certificate to be used in the handshake.  You are advised to use
     'gnutls_certificate_set_retrieve_function2()' because it is much
     more efficient in the processing it requires from gnutls.

     The callback's function prototype is: int
     (*callback)(gnutls_session_t, const gnutls_datum_t* req_ca_dn, int
     nreqs, const gnutls_pk_algorithm_t* pk_algos, int pk_algos_length,
     gnutls_retr2_st* st);

     'req_ca_dn' is only used in X.509 certificates.  Contains a list
     with the CA names that the server considers trusted.  Normally we
     should send a certificate that is signed by one of these CAs.
     These names are DER encoded.  To get a more meaningful value use
     the function 'gnutls_x509_rdn_get()' .

     'pk_algos' contains a list with server's acceptable signature
     algorithms.  The certificate returned should support the server's
     given algorithms.

     'st' should contain the certificates and private keys.

     If the callback function is provided then gnutls will call it, in
     the handshake, after the certificate request message has been
     received.

     In server side pk_algos and req_ca_dn are NULL.

     The callback function should set the certificate list to be sent,
     and return 0 on success.  If no certificate was selected then the
     number of certificates should be set to zero.  The value (-1)
     indicates error and the handshake will be terminated.

     *Since:* 3.0

gnutls_certificate_set_verify_flags
-----------------------------------

 -- Function: void gnutls_certificate_set_verify_flags
          (gnutls_certificate_credentials_t RES, unsigned int FLAGS)
     RES: is a gnutls_certificate_credentials_t structure

     FLAGS: are the flags

     This function will set the flags to be used for verification of
     certificates and override any defaults.  The provided flags must be
     an OR of the 'gnutls_certificate_verify_flags' enumerations.

gnutls_certificate_set_verify_function
--------------------------------------

 -- Function: void gnutls_certificate_set_verify_function
          (gnutls_certificate_credentials_t CRED,
          gnutls_certificate_verify_function * FUNC)
     CRED: is a 'gnutls_certificate_credentials_t' structure.

     FUNC: is the callback function

     This function sets a callback to be called when peer's certificate
     has been received in order to verify it on receipt rather than
     doing after the handshake is completed.

     The callback's function prototype is: int
     (*callback)(gnutls_session_t);

     If the callback function is provided then gnutls will call it, in
     the handshake, just after the certificate message has been
     received.  To verify or obtain the certificate the
     'gnutls_certificate_verify_peers2()' ,
     'gnutls_certificate_type_get()' , 'gnutls_certificate_get_peers()'
     functions can be used.

     The callback function should return 0 for the handshake to continue
     or non-zero to terminate.

     *Since:* 2.10.0

gnutls_certificate_set_verify_limits
------------------------------------

 -- Function: void gnutls_certificate_set_verify_limits
          (gnutls_certificate_credentials_t RES, unsigned int MAX_BITS,
          unsigned int MAX_DEPTH)
     RES: is a gnutls_certificate_credentials structure

     MAX_BITS: is the number of bits of an acceptable certificate
     (default 8200)

     MAX_DEPTH: is maximum depth of the verification of a certificate
     chain (default 5)

     This function will set some upper limits for the default
     verification function, 'gnutls_certificate_verify_peers2()' , to
     avoid denial of service attacks.  You can set them to zero to
     disable limits.

gnutls_certificate_set_x509_crl
-------------------------------

 -- Function: int gnutls_certificate_set_x509_crl
          (gnutls_certificate_credentials_t RES, gnutls_x509_crl_t *
          CRL_LIST, int CRL_LIST_SIZE)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CRL_LIST: is a list of trusted CRLs.  They should have been
     verified before.

     CRL_LIST_SIZE: holds the size of the crl_list

     This function adds the trusted CRLs in order to verify client or
     server certificates.  In case of a client this is not required to
     be called if the certificates are not verified using
     'gnutls_certificate_verify_peers2()' .  This function may be called
     multiple times.

     *Returns:* number of CRLs processed, or a negative error code on
     error.

     *Since:* 2.4.0

gnutls_certificate_set_x509_crl_file
------------------------------------

 -- Function: int gnutls_certificate_set_x509_crl_file
          (gnutls_certificate_credentials_t RES, const char * CRLFILE,
          gnutls_x509_crt_fmt_t TYPE)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CRLFILE: is a file containing the list of verified CRLs (DER or PEM
     list)

     TYPE: is PEM or DER

     This function adds the trusted CRLs in order to verify client or
     server certificates.  In case of a client this is not required to
     be called if the certificates are not verified using
     'gnutls_certificate_verify_peers2()' .  This function may be called
     multiple times.

     *Returns:* number of CRLs processed or a negative error code on
     error.

gnutls_certificate_set_x509_crl_mem
-----------------------------------

 -- Function: int gnutls_certificate_set_x509_crl_mem
          (gnutls_certificate_credentials_t RES, const gnutls_datum_t *
          CRL, gnutls_x509_crt_fmt_t TYPE)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CRL: is a list of trusted CRLs.  They should have been verified
     before.

     TYPE: is DER or PEM

     This function adds the trusted CRLs in order to verify client or
     server certificates.  In case of a client this is not required to
     be called if the certificates are not verified using
     'gnutls_certificate_verify_peers2()' .  This function may be called
     multiple times.

     *Returns:* number of CRLs processed, or a negative error code on
     error.

gnutls_certificate_set_x509_key
-------------------------------

 -- Function: int gnutls_certificate_set_x509_key
          (gnutls_certificate_credentials_t RES, gnutls_x509_crt_t *
          CERT_LIST, int CERT_LIST_SIZE, gnutls_x509_privkey_t KEY)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CERT_LIST: contains a certificate list (path) for the specified
     private key

     CERT_LIST_SIZE: holds the size of the certificate list

     KEY: is a 'gnutls_x509_privkey_t' key

     This function sets a certificate/private key pair in the
     gnutls_certificate_credentials_t structure.  This function may be
     called more than once, in case multiple keys/certificates exist for
     the server.  For clients that wants to send more than their own end
     entity certificate (e.g., also an intermediate CA cert) then put
     the certificate chain in 'cert_list' .

     Note that the certificates and keys provided, can be safely
     deinitialized after this function is called.

     If that function fails to load the 'res' structure is at an
     undefined state, it must not be reused to load other keys or
     certificates.

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

     *Since:* 2.4.0

gnutls_certificate_set_x509_key_file
------------------------------------

 -- Function: int gnutls_certificate_set_x509_key_file
          (gnutls_certificate_credentials_t RES, const char * CERTFILE,
          const char * KEYFILE, gnutls_x509_crt_fmt_t TYPE)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CERTFILE: is a file that containing the certificate list (path) for
     the specified private key, in PKCS7 format, or a list of
     certificates

     KEYFILE: is a file that contains the private key

     TYPE: is PEM or DER

     This function sets a certificate/private key pair in the
     gnutls_certificate_credentials_t structure.  This function may be
     called more than once, in case multiple keys/certificates exist for
     the server.  For clients that need to send more than its own end
     entity certificate, e.g., also an intermediate CA cert, then the
     'certfile' must contain the ordered certificate chain.

     Note that the names in the certificate provided will be considered
     when selecting the appropriate certificate to use (in case of
     multiple certificate/key pairs).

     This function can also accept URLs at 'keyfile' and 'certfile' .
     In that case it will import the private key and certificate
     indicated by the URLs.  Note that the supported URLs are the ones
     indicated by 'gnutls_url_is_supported()' .

     In case the 'certfile' is provided as a PKCS '11' URL, then the
     certificate, and its present issuers in the token are are imported
     (i.e., the required trust chain).

     If that function fails to load the 'res' structure is at an
     undefined state, it must not be reused to load other keys or
     certificates.

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

gnutls_certificate_set_x509_key_file2
-------------------------------------

 -- Function: int gnutls_certificate_set_x509_key_file2
          (gnutls_certificate_credentials_t RES, const char * CERTFILE,
          const char * KEYFILE, gnutls_x509_crt_fmt_t TYPE, const char *
          PASS, unsigned int FLAGS)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CERTFILE: is a file that containing the certificate list (path) for
     the specified private key, in PKCS7 format, or a list of
     certificates

     KEYFILE: is a file that contains the private key

     TYPE: is PEM or DER

     PASS: is the password of the key

     FLAGS: an ORed sequence of gnutls_pkcs_encrypt_flags_t

     This function sets a certificate/private key pair in the
     gnutls_certificate_credentials_t structure.  This function may be
     called more than once, in case multiple keys/certificates exist for
     the server.  For clients that need to send more than its own end
     entity certificate, e.g., also an intermediate CA cert, then the
     'certfile' must contain the ordered certificate chain.

     Note that the names in the certificate provided will be considered
     when selecting the appropriate certificate to use (in case of
     multiple certificate/key pairs).

     This function can also accept URLs at 'keyfile' and 'certfile' .
     In that case it will import the private key and certificate
     indicated by the URLs.  Note that the supported URLs are the ones
     indicated by 'gnutls_url_is_supported()' .

     In case the 'certfile' is provided as a PKCS '11' URL, then the
     certificate, and its present issuers in the token are are imported
     (i.e., the required trust chain).

     If that function fails to load the 'res' structure is at an
     undefined state, it must not be reused to load other keys or
     certificates.

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

gnutls_certificate_set_x509_key_mem
-----------------------------------

 -- Function: int gnutls_certificate_set_x509_key_mem
          (gnutls_certificate_credentials_t RES, const gnutls_datum_t *
          CERT, const gnutls_datum_t * KEY, gnutls_x509_crt_fmt_t TYPE)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CERT: contains a certificate list (path) for the specified private
     key

     KEY: is the private key, or 'NULL'

     TYPE: is PEM or DER

     This function sets a certificate/private key pair in the
     gnutls_certificate_credentials_t structure.  This function may be
     called more than once, in case multiple keys/certificates exist for
     the server.

     Note that the keyUsage (2.5.29.15) PKIX extension in X.509
     certificates is supported.  This means that certificates intended
     for signing cannot be used for ciphersuites that require
     encryption.

     If the certificate and the private key are given in PEM encoding
     then the strings that hold their values must be null terminated.

     The 'key' may be 'NULL' if you are using a sign callback, see
     'gnutls_sign_callback_set()' .

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

gnutls_certificate_set_x509_key_mem2
------------------------------------

 -- Function: int gnutls_certificate_set_x509_key_mem2
          (gnutls_certificate_credentials_t RES, const gnutls_datum_t *
          CERT, const gnutls_datum_t * KEY, gnutls_x509_crt_fmt_t TYPE,
          const char * PASS, unsigned int FLAGS)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CERT: contains a certificate list (path) for the specified private
     key

     KEY: is the private key, or 'NULL'

     TYPE: is PEM or DER

     PASS: is the key's password

     FLAGS: an ORed sequence of gnutls_pkcs_encrypt_flags_t

     This function sets a certificate/private key pair in the
     gnutls_certificate_credentials_t structure.  This function may be
     called more than once, in case multiple keys/certificates exist for
     the server.

     Note that the keyUsage (2.5.29.15) PKIX extension in X.509
     certificates is supported.  This means that certificates intended
     for signing cannot be used for ciphersuites that require
     encryption.

     If the certificate and the private key are given in PEM encoding
     then the strings that hold their values must be null terminated.

     The 'key' may be 'NULL' if you are using a sign callback, see
     'gnutls_sign_callback_set()' .

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

gnutls_certificate_set_x509_simple_pkcs12_file
----------------------------------------------

 -- Function: int gnutls_certificate_set_x509_simple_pkcs12_file
          (gnutls_certificate_credentials_t RES, const char *
          PKCS12FILE, gnutls_x509_crt_fmt_t TYPE, const char * PASSWORD)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     PKCS12FILE: filename of file containing PKCS'12' blob.

     TYPE: is PEM or DER of the 'pkcs12file' .

     PASSWORD: optional password used to decrypt PKCS'12' file, bags and
     keys.

     This function sets a certificate/private key pair and/or a CRL in
     the gnutls_certificate_credentials_t structure.  This function may
     be called more than once (in case multiple keys/certificates exist
     for the server).

     PKCS'12' files with a MAC, encrypted bags and PKCS '8' private keys
     are supported.  However, only password based security, and the same
     password for all operations, are supported.

     PKCS'12' file may contain many keys and/or certificates, and this
     function will try to auto-detect based on the key ID the
     certificate and key pair to use.  If the PKCS'12' file contain the
     issuer of the selected certificate, it will be appended to the
     certificate to form a chain.

     If more than one private keys are stored in the PKCS'12' file, then
     only one key will be read (and it is undefined which one).

     It is believed that the limitations of this function is acceptable
     for most usage, and that any more flexibility would introduce
     complexity that would make it harder to use this functionality at
     all.

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

gnutls_certificate_set_x509_simple_pkcs12_mem
---------------------------------------------

 -- Function: int gnutls_certificate_set_x509_simple_pkcs12_mem
          (gnutls_certificate_credentials_t RES, const gnutls_datum_t *
          P12BLOB, gnutls_x509_crt_fmt_t TYPE, const char * PASSWORD)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     P12BLOB: the PKCS'12' blob.

     TYPE: is PEM or DER of the 'pkcs12file' .

     PASSWORD: optional password used to decrypt PKCS'12' file, bags and
     keys.

     This function sets a certificate/private key pair and/or a CRL in
     the gnutls_certificate_credentials_t structure.  This function may
     be called more than once (in case multiple keys/certificates exist
     for the server).

     Encrypted PKCS'12' bags and PKCS'8' private keys are supported.
     However, only password based security, and the same password for
     all operations, are supported.

     PKCS'12' file may contain many keys and/or certificates, and this
     function will try to auto-detect based on the key ID the
     certificate and key pair to use.  If the PKCS'12' file contain the
     issuer of the selected certificate, it will be appended to the
     certificate to form a chain.

     If more than one private keys are stored in the PKCS'12' file, then
     only one key will be read (and it is undefined which one).

     It is believed that the limitations of this function is acceptable
     for most usage, and that any more flexibility would introduce
     complexity that would make it harder to use this functionality at
     all.

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

     *Since:* 2.8.0

gnutls_certificate_set_x509_system_trust
----------------------------------------

 -- Function: int gnutls_certificate_set_x509_system_trust
          (gnutls_certificate_credentials_t CRED)
     CRED: is a 'gnutls_certificate_credentials_t' structure.

     This function adds the system's default trusted CAs in order to
     verify client or server certificates.

     In the case the system is currently unsupported
     'GNUTLS_E_UNIMPLEMENTED_FEATURE' is returned.

     *Returns:* the number of certificates processed or a negative error
     code on error.

     *Since:* 3.0.20

gnutls_certificate_set_x509_trust
---------------------------------

 -- Function: int gnutls_certificate_set_x509_trust
          (gnutls_certificate_credentials_t RES, gnutls_x509_crt_t *
          CA_LIST, int CA_LIST_SIZE)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CA_LIST: is a list of trusted CAs

     CA_LIST_SIZE: holds the size of the CA list

     This function adds the trusted CAs in order to verify client or
     server certificates.  In case of a client this is not required to
     be called if the certificates are not verified using
     'gnutls_certificate_verify_peers2()' .  This function may be called
     multiple times.

     In case of a server the CAs set here will be sent to the client if
     a certificate request is sent.  This can be disabled using
     'gnutls_certificate_send_x509_rdn_sequence()' .

     *Returns:* the number of certificates processed or a negative error
     code on error.

     *Since:* 2.4.0

gnutls_certificate_set_x509_trust_dir
-------------------------------------

 -- Function: int gnutls_certificate_set_x509_trust_dir
          (gnutls_certificate_credentials_t CRED, const char * CA_DIR,
          gnutls_x509_crt_fmt_t TYPE)
     CRED: is a 'gnutls_certificate_credentials_t' structure.

     CA_DIR: is a directory containing the list of trusted CAs (DER or
     PEM list)

     TYPE: is PEM or DER

     This function adds the trusted CAs present in the directory in
     order to verify client or server certificates.  This function is
     identical to 'gnutls_certificate_set_x509_trust_file()' but loads
     all certificates in a directory.

     *Returns:* the number of certificates processed

     *Since:* 3.3.6

gnutls_certificate_set_x509_trust_file
--------------------------------------

 -- Function: int gnutls_certificate_set_x509_trust_file
          (gnutls_certificate_credentials_t CRED, const char * CAFILE,
          gnutls_x509_crt_fmt_t TYPE)
     CRED: is a 'gnutls_certificate_credentials_t' structure.

     CAFILE: is a file containing the list of trusted CAs (DER or PEM
     list)

     TYPE: is PEM or DER

     This function adds the trusted CAs in order to verify client or
     server certificates.  In case of a client this is not required to
     be called if the certificates are not verified using
     'gnutls_certificate_verify_peers2()' .  This function may be called
     multiple times.

     In case of a server the names of the CAs set here will be sent to
     the client if a certificate request is sent.  This can be disabled
     using 'gnutls_certificate_send_x509_rdn_sequence()' .

     This function can also accept URLs.  In that case it will import
     all certificates that are marked as trusted.  Note that the
     supported URLs are the ones indicated by
     'gnutls_url_is_supported()' .

     *Returns:* the number of certificates processed

gnutls_certificate_set_x509_trust_mem
-------------------------------------

 -- Function: int gnutls_certificate_set_x509_trust_mem
          (gnutls_certificate_credentials_t RES, const gnutls_datum_t *
          CA, gnutls_x509_crt_fmt_t TYPE)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     CA: is a list of trusted CAs or a DER certificate

     TYPE: is DER or PEM

     This function adds the trusted CAs in order to verify client or
     server certificates.  In case of a client this is not required to
     be called if the certificates are not verified using
     'gnutls_certificate_verify_peers2()' .  This function may be called
     multiple times.

     In case of a server the CAs set here will be sent to the client if
     a certificate request is sent.  This can be disabled using
     'gnutls_certificate_send_x509_rdn_sequence()' .

     *Returns:* the number of certificates processed or a negative error
     code on error.

gnutls_certificate_type_get
---------------------------

 -- Function: gnutls_certificate_type_t gnutls_certificate_type_get
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     The certificate type is by default X.509, unless it is negotiated
     as a TLS extension.

     *Returns:* the currently used 'gnutls_certificate_type_t'
     certificate type.

gnutls_certificate_type_get_id
------------------------------

 -- Function: gnutls_certificate_type_t gnutls_certificate_type_get_id
          (const char * NAME)
     NAME: is a certificate type name

     The names are compared in a case insensitive way.

     *Returns:* a 'gnutls_certificate_type_t' for the specified in a
     string certificate type, or 'GNUTLS_CRT_UNKNOWN' on error.

gnutls_certificate_type_get_name
--------------------------------

 -- Function: const char * gnutls_certificate_type_get_name
          (gnutls_certificate_type_t TYPE)
     TYPE: is a certificate type

     Convert a 'gnutls_certificate_type_t' type to a string.

     *Returns:* a string that contains the name of the specified
     certificate type, or 'NULL' in case of unknown types.

gnutls_certificate_type_list
----------------------------

 -- Function: const gnutls_certificate_type_t *
          gnutls_certificate_type_list ( VOID)

     Get a list of certificate types.

     *Returns:* a (0)-terminated list of 'gnutls_certificate_type_t'
     integers indicating the available certificate types.

gnutls_certificate_verification_status_print
--------------------------------------------

 -- Function: int gnutls_certificate_verification_status_print (unsigned
          int STATUS, gnutls_certificate_type_t TYPE, gnutls_datum_t *
          OUT, unsigned int FLAGS)
     STATUS: The status flags to be printed

     TYPE: The certificate type

     OUT: Newly allocated datum with (0) terminated string.

     FLAGS: should be zero

     This function will pretty print the status of a verification
     process - eg.  the one obtained by
     'gnutls_certificate_verify_peers3()' .

     The output 'out' needs to be deallocated using 'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.1.4

gnutls_certificate_verify_peers
-------------------------------

 -- Function: int gnutls_certificate_verify_peers (gnutls_session_t
          SESSION, gnutls_typed_vdata_st * DATA, unsigned int ELEMENTS,
          unsigned int * STATUS)
     SESSION: is a gnutls session

     DATA: an array of typed data

     ELEMENTS: the number of data elements

     STATUS: is the output of the verification

     This function will verify the peer's certificate and store the
     status in the 'status' variable as a bitwise or'd
     gnutls_certificate_status_t values or zero if the certificate is
     trusted.  Note that value in 'status' is set only when the return
     value of this function is success (i.e, failure to trust a
     certificate does not imply a negative return value).  The default
     verification flags used by this function can be overridden using
     'gnutls_certificate_set_verify_flags()' .  See the documentation of
     'gnutls_certificate_verify_peers2()' for details in the
     verification process.

     The acceptable 'data' types are 'GNUTLS_DT_DNS_HOSTNAME' and
     'GNUTLS_DT_KEY_PURPOSE_OID' .  The former accepts as data a
     null-terminated hostname, and the latter a null-terminated object
     identifier (e.g., 'GNUTLS_KP_TLS_WWW_SERVER' ).  If a DNS hostname
     is provided then this function will compare the hostname in the
     certificate against the given.  If names do not match the
     'GNUTLS_CERT_UNEXPECTED_OWNER' status flag will be set.  If a key
     purpose OID is provided and the end-certificate contains the
     extended key usage PKIX extension, it will be required to be have
     the provided key purpose or be marked for any purpose, otherwise
     verification will fail with
     'GNUTLS_CERT_SIGNER_CONSTRAINTS_FAILURE' status.

     *Returns:* a negative error code on error and 'GNUTLS_E_SUCCESS'
     (0) when the peer's certificate was successfully parsed,
     irrespective of whether it was verified.

     *Since:* 3.3.0

gnutls_certificate_verify_peers2
--------------------------------

 -- Function: int gnutls_certificate_verify_peers2 (gnutls_session_t
          SESSION, unsigned int * STATUS)
     SESSION: is a gnutls session

     STATUS: is the output of the verification

     This function will verify the peer's certificate and store the
     status in the 'status' variable as a bitwise or'd
     gnutls_certificate_status_t values or zero if the certificate is
     trusted.  Note that value in 'status' is set only when the return
     value of this function is success (i.e, failure to trust a
     certificate does not imply a negative return value).  The default
     verification flags used by this function can be overridden using
     'gnutls_certificate_set_verify_flags()' .

     This function will take into account the OCSP Certificate Status
     TLS extension, as well as the following X.509 certificate
     extensions: Name Constraints, Key Usage, and Basic Constraints
     (pathlen).

     To avoid denial of service attacks some default upper limits
     regarding the certificate key size and chain size are set.  To
     override them use 'gnutls_certificate_set_verify_limits()' .

     Note that you must also check the peer's name in order to check if
     the verified certificate belongs to the actual peer, see
     'gnutls_x509_crt_check_hostname()' , or use
     'gnutls_certificate_verify_peers3()' .

     *Returns:* a negative error code on error and 'GNUTLS_E_SUCCESS'
     (0) when the peer's certificate was successfully parsed,
     irrespective of whether it was verified.

gnutls_certificate_verify_peers3
--------------------------------

 -- Function: int gnutls_certificate_verify_peers3 (gnutls_session_t
          SESSION, const char * HOSTNAME, unsigned int * STATUS)
     SESSION: is a gnutls session

     HOSTNAME: is the expected name of the peer; may be 'NULL'

     STATUS: is the output of the verification

     This function will verify the peer's certificate and store the
     status in the 'status' variable as a bitwise or'd
     gnutls_certificate_status_t values or zero if the certificate is
     trusted.  Note that value in 'status' is set only when the return
     value of this function is success (i.e, failure to trust a
     certificate does not imply a negative return value).  The default
     verification flags used by this function can be overridden using
     'gnutls_certificate_set_verify_flags()' .  See the documentation of
     'gnutls_certificate_verify_peers2()' for details in the
     verification process.

     If the 'hostname' provided is non-NULL then this function will
     compare the hostname in the certificate against the given.  The
     comparison will be accurate for ascii names; non-ascii names are
     compared byte-by-byte.  If names do not match the
     'GNUTLS_CERT_UNEXPECTED_OWNER' status flag will be set.

     In order to verify the purpose of the end-certificate (by checking
     the extended key usage), use 'gnutls_certificate_verify_peers()' .

     *Returns:* a negative error code on error and 'GNUTLS_E_SUCCESS'
     (0) when the peer's certificate was successfully parsed,
     irrespective of whether it was verified.

     *Since:* 3.1.4

gnutls_check_version
--------------------

 -- Function: const char * gnutls_check_version (const char *
          REQ_VERSION)
     REQ_VERSION: version string to compare with, or 'NULL' .

     Check GnuTLS Library version.

     See 'GNUTLS_VERSION' for a suitable 'req_version' string.

     *Returns:* Check that the version of the library is at minimum the
     one given as a string in 'req_version' and return the actual
     version string of the library; return 'NULL' if the condition is
     not met.  If 'NULL' is passed to this function no check is done and
     only the version string is returned.

gnutls_cipher_get
-----------------

 -- Function: gnutls_cipher_algorithm_t gnutls_cipher_get
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get currently used cipher.

     *Returns:* the currently used cipher, a 'gnutls_cipher_algorithm_t'
     type.

gnutls_cipher_get_id
--------------------

 -- Function: gnutls_cipher_algorithm_t gnutls_cipher_get_id (const char
          * NAME)
     NAME: is a cipher algorithm name

     The names are compared in a case insensitive way.

     *Returns:* return a 'gnutls_cipher_algorithm_t' value corresponding
     to the specified cipher, or 'GNUTLS_CIPHER_UNKNOWN' on error.

gnutls_cipher_get_key_size
--------------------------

 -- Function: size_t gnutls_cipher_get_key_size
          (gnutls_cipher_algorithm_t ALGORITHM)
     ALGORITHM: is an encryption algorithm

     Get key size for cipher.

     *Returns:* length (in bytes) of the given cipher's key size, or 0
     if the given cipher is invalid.

gnutls_cipher_get_name
----------------------

 -- Function: const char * gnutls_cipher_get_name
          (gnutls_cipher_algorithm_t ALGORITHM)
     ALGORITHM: is an encryption algorithm

     Convert a 'gnutls_cipher_algorithm_t' type to a string.

     *Returns:* a pointer to a string that contains the name of the
     specified cipher, or 'NULL' .

gnutls_cipher_list
------------------

 -- Function: const gnutls_cipher_algorithm_t * gnutls_cipher_list (
          VOID)

     Get a list of supported cipher algorithms.  Note that not
     necessarily all ciphers are supported as TLS cipher suites.  For
     example, DES is not supported as a cipher suite, but is supported
     for other purposes (e.g., PKCS'8' or similar).

     This function is not thread safe.

     *Returns:* a (0)-terminated list of 'gnutls_cipher_algorithm_t'
     integers indicating the available ciphers.

gnutls_cipher_suite_get_name
----------------------------

 -- Function: const char * gnutls_cipher_suite_get_name
          (gnutls_kx_algorithm_t KX_ALGORITHM, gnutls_cipher_algorithm_t
          CIPHER_ALGORITHM, gnutls_mac_algorithm_t MAC_ALGORITHM)
     KX_ALGORITHM: is a Key exchange algorithm

     CIPHER_ALGORITHM: is a cipher algorithm

     MAC_ALGORITHM: is a MAC algorithm

     Note that the full cipher suite name must be prepended by TLS or
     SSL depending of the protocol in use.

     *Returns:* a string that contains the name of a TLS cipher suite,
     specified by the given algorithms, or 'NULL' .

gnutls_cipher_suite_info
------------------------

 -- Function: const char * gnutls_cipher_suite_info (size_t IDX,
          unsigned char * CS_ID, gnutls_kx_algorithm_t * KX,
          gnutls_cipher_algorithm_t * CIPHER, gnutls_mac_algorithm_t *
          MAC, gnutls_protocol_t * MIN_VERSION)
     IDX: index of cipher suite to get information about, starts on 0.

     CS_ID: output buffer with room for 2 bytes, indicating cipher suite
     value

     KX: output variable indicating key exchange algorithm, or 'NULL' .

     CIPHER: output variable indicating cipher, or 'NULL' .

     MAC: output variable indicating MAC algorithm, or 'NULL' .

     MIN_VERSION: output variable indicating TLS protocol version, or
     'NULL' .

     Get information about supported cipher suites.  Use the function
     iteratively to get information about all supported cipher suites.
     Call with idx=0 to get information about first cipher suite, then
     idx=1 and so on until the function returns NULL.

     *Returns:* the name of 'idx' cipher suite, and set the information
     about the cipher suite in the output variables.  If 'idx' is out of
     bounds, 'NULL' is returned.

gnutls_compression_get
----------------------

 -- Function: gnutls_compression_method_t gnutls_compression_get
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get currently used compression algorithm.

     *Returns:* the currently used compression method, a
     'gnutls_compression_method_t' value.

gnutls_compression_get_id
-------------------------

 -- Function: gnutls_compression_method_t gnutls_compression_get_id
          (const char * NAME)
     NAME: is a compression method name

     The names are compared in a case insensitive way.

     *Returns:* an id of the specified in a string compression method,
     or 'GNUTLS_COMP_UNKNOWN' on error.

gnutls_compression_get_name
---------------------------

 -- Function: const char * gnutls_compression_get_name
          (gnutls_compression_method_t ALGORITHM)
     ALGORITHM: is a Compression algorithm

     Convert a 'gnutls_compression_method_t' value to a string.

     *Returns:* a pointer to a string that contains the name of the
     specified compression algorithm, or 'NULL' .

gnutls_compression_list
-----------------------

 -- Function: const gnutls_compression_method_t *
          gnutls_compression_list ( VOID)

     Get a list of compression methods.

     *Returns:* a zero-terminated list of 'gnutls_compression_method_t'
     integers indicating the available compression methods.

gnutls_credentials_clear
------------------------

 -- Function: void gnutls_credentials_clear (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Clears all the credentials previously set in this session.

gnutls_credentials_get
----------------------

 -- Function: int gnutls_credentials_get (gnutls_session_t SESSION,
          gnutls_credentials_type_t TYPE, void ** CRED)
     SESSION: is a 'gnutls_session_t' structure.

     TYPE: is the type of the credentials to return

     CRED: will contain the pointer to the credentials structure.

     Returns the previously provided credentials structures.

     For 'GNUTLS_CRD_ANON' , 'cred' will be
     'gnutls_anon_client_credentials_t' in case of a client.  In case of
     a server it should be 'gnutls_anon_server_credentials_t' .

     For 'GNUTLS_CRD_SRP' , 'cred' will be
     'gnutls_srp_client_credentials_t' in case of a client, and
     'gnutls_srp_server_credentials_t' , in case of a server.

     For 'GNUTLS_CRD_CERTIFICATE' , 'cred' will be
     'gnutls_certificate_credentials_t' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_credentials_set
----------------------

 -- Function: int gnutls_credentials_set (gnutls_session_t SESSION,
          gnutls_credentials_type_t TYPE, void * CRED)
     SESSION: is a 'gnutls_session_t' structure.

     TYPE: is the type of the credentials

     CRED: is a pointer to a structure.

     Sets the needed credentials for the specified type.  Eg username,
     password - or public and private keys etc.  The 'cred' parameter is
     a structure that depends on the specified type and on the current
     session (client or server).

     In order to minimize memory usage, and share credentials between
     several threads gnutls keeps a pointer to cred, and not the whole
     cred structure.  Thus you will have to keep the structure allocated
     until you call 'gnutls_deinit()' .

     For 'GNUTLS_CRD_ANON' , 'cred' should be
     'gnutls_anon_client_credentials_t' in case of a client.  In case of
     a server it should be 'gnutls_anon_server_credentials_t' .

     For 'GNUTLS_CRD_SRP' , 'cred' should be
     'gnutls_srp_client_credentials_t' in case of a client, and
     'gnutls_srp_server_credentials_t' , in case of a server.

     For 'GNUTLS_CRD_CERTIFICATE' , 'cred' should be
     'gnutls_certificate_credentials_t' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_db_check_entry
---------------------

 -- Function: int gnutls_db_check_entry (gnutls_session_t SESSION,
          gnutls_datum_t SESSION_ENTRY)
     SESSION: is a 'gnutls_session_t' structure.

     SESSION_ENTRY: is the session data (not key)

     This function has no effect.

     *Returns:* Returns 'GNUTLS_E_EXPIRED' , if the database entry has
     expired or 0 otherwise.

gnutls_db_check_entry_time
--------------------------

 -- Function: time_t gnutls_db_check_entry_time (gnutls_datum_t * ENTRY)
     ENTRY: is a pointer to a 'gnutls_datum_t' structure.

     This function returns the time that this entry was active.  It can
     be used for database entry expiration.

     *Returns:* The time this entry was created, or zero on error.

gnutls_db_get_default_cache_expiration
--------------------------------------

 -- Function: unsigned gnutls_db_get_default_cache_expiration ( VOID)

     Returns the expiration time (in seconds) of stored sessions for
     resumption.

gnutls_db_get_ptr
-----------------

 -- Function: void * gnutls_db_get_ptr (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get db function pointer.

     *Returns:* the pointer that will be sent to db store, retrieve and
     delete functions, as the first argument.

gnutls_db_remove_session
------------------------

 -- Function: void gnutls_db_remove_session (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function will remove the current session data from the session
     database.  This will prevent future handshakes reusing these
     session data.  This function should be called if a session was
     terminated abnormally, and before 'gnutls_deinit()' is called.

     Normally 'gnutls_deinit()' will remove abnormally terminated
     sessions.

gnutls_db_set_cache_expiration
------------------------------

 -- Function: void gnutls_db_set_cache_expiration (gnutls_session_t
          SESSION, int SECONDS)
     SESSION: is a 'gnutls_session_t' structure.

     SECONDS: is the number of seconds.

     Set the expiration time for resumed sessions.  The default is 3600
     (one hour) at the time of this writing.

gnutls_db_set_ptr
-----------------

 -- Function: void gnutls_db_set_ptr (gnutls_session_t SESSION, void *
          PTR)
     SESSION: is a 'gnutls_session_t' structure.

     PTR: is the pointer

     Sets the pointer that will be provided to db store, retrieve and
     delete functions, as the first argument.

gnutls_db_set_remove_function
-----------------------------

 -- Function: void gnutls_db_set_remove_function (gnutls_session_t
          SESSION, gnutls_db_remove_func REM_FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     REM_FUNC: is the function.

     Sets the function that will be used to remove data from the resumed
     sessions database.  This function must return 0 on success.

     The first argument to 'rem_func' will be null unless
     'gnutls_db_set_ptr()' has been called.

gnutls_db_set_retrieve_function
-------------------------------

 -- Function: void gnutls_db_set_retrieve_function (gnutls_session_t
          SESSION, gnutls_db_retr_func RETR_FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     RETR_FUNC: is the function.

     Sets the function that will be used to retrieve data from the
     resumed sessions database.  This function must return a
     gnutls_datum_t containing the data on success, or a gnutls_datum_t
     containing null and 0 on failure.

     The datum's data must be allocated using the function
     'gnutls_malloc()' .

     The first argument to 'retr_func' will be null unless
     'gnutls_db_set_ptr()' has been called.

gnutls_db_set_store_function
----------------------------

 -- Function: void gnutls_db_set_store_function (gnutls_session_t
          SESSION, gnutls_db_store_func STORE_FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     STORE_FUNC: is the function

     Sets the function that will be used to store data in the resumed
     sessions database.  This function must return 0 on success.

     The first argument to 'store_func' will be null unless
     'gnutls_db_set_ptr()' has been called.

gnutls_deinit
-------------

 -- Function: void gnutls_deinit (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function clears all buffers associated with the 'session' .
     This function will also remove session data from the session
     database if the session was terminated abnormally.

gnutls_dh_get_group
-------------------

 -- Function: int gnutls_dh_get_group (gnutls_session_t SESSION,
          gnutls_datum_t * RAW_GEN, gnutls_datum_t * RAW_PRIME)
     SESSION: is a gnutls session

     RAW_GEN: will hold the generator.

     RAW_PRIME: will hold the prime.

     This function will return the group parameters used in the last
     Diffie-Hellman key exchange with the peer.  These are the prime and
     the generator used.  This function should be used for both
     anonymous and ephemeral Diffie-Hellman.  The output parameters must
     be freed with 'gnutls_free()' .

     Note, that the prime and generator are exported as non-negative
     integers and may include a leading zero byte.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_dh_get_peers_public_bits
-------------------------------

 -- Function: int gnutls_dh_get_peers_public_bits (gnutls_session_t
          SESSION)
     SESSION: is a gnutls session

     Get the Diffie-Hellman public key bit size.  Can be used for both
     anonymous and ephemeral Diffie-Hellman.

     *Returns:* The public key bit size used in the last Diffie-Hellman
     key exchange with the peer, or a negative error code in case of
     error.

gnutls_dh_get_prime_bits
------------------------

 -- Function: int gnutls_dh_get_prime_bits (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     This function will return the bits of the prime used in the last
     Diffie-Hellman key exchange with the peer.  Should be used for both
     anonymous and ephemeral Diffie-Hellman.  Note that some ciphers,
     like RSA and DSA without DHE, do not use a Diffie-Hellman key
     exchange, and then this function will return 0.

     *Returns:* The Diffie-Hellman bit strength is returned, or 0 if no
     Diffie-Hellman key exchange was done, or a negative error code on
     failure.

gnutls_dh_get_pubkey
--------------------

 -- Function: int gnutls_dh_get_pubkey (gnutls_session_t SESSION,
          gnutls_datum_t * RAW_KEY)
     SESSION: is a gnutls session

     RAW_KEY: will hold the public key.

     This function will return the peer's public key used in the last
     Diffie-Hellman key exchange.  This function should be used for both
     anonymous and ephemeral Diffie-Hellman.  The output parameters must
     be freed with 'gnutls_free()' .

     Note, that public key is exported as non-negative integer and may
     include a leading zero byte.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_dh_get_secret_bits
-------------------------

 -- Function: int gnutls_dh_get_secret_bits (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     This function will return the bits used in the last Diffie-Hellman
     key exchange with the peer.  Should be used for both anonymous and
     ephemeral Diffie-Hellman.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_dh_params_cpy
--------------------

 -- Function: int gnutls_dh_params_cpy (gnutls_dh_params_t DST,
          gnutls_dh_params_t SRC)
     DST: Is the destination structure, which should be initialized.

     SRC: Is the source structure

     This function will copy the DH parameters structure from source to
     destination.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_dh_params_deinit
-----------------------

 -- Function: void gnutls_dh_params_deinit (gnutls_dh_params_t
          DH_PARAMS)
     DH_PARAMS: Is a structure that holds the prime numbers

     This function will deinitialize the DH parameters structure.

gnutls_dh_params_export2_pkcs3
------------------------------

 -- Function: int gnutls_dh_params_export2_pkcs3 (gnutls_dh_params_t
          PARAMS, gnutls_x509_crt_fmt_t FORMAT, gnutls_datum_t * OUT)
     PARAMS: Holds the DH parameters

     FORMAT: the format of output params.  One of PEM or DER.

     OUT: will contain a PKCS3 DHParams structure PEM or DER encoded

     This function will export the given dh parameters to a PKCS3
     DHParams structure.  This is the format generated by "openssl
     dhparam" tool.  The data in 'out' will be allocated using
     'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN DH
     PARAMETERS".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     *Since:* 3.1.3

gnutls_dh_params_export_pkcs3
-----------------------------

 -- Function: int gnutls_dh_params_export_pkcs3 (gnutls_dh_params_t
          PARAMS, gnutls_x509_crt_fmt_t FORMAT, unsigned char *
          PARAMS_DATA, size_t * PARAMS_DATA_SIZE)
     PARAMS: Holds the DH parameters

     FORMAT: the format of output params.  One of PEM or DER.

     PARAMS_DATA: will contain a PKCS3 DHParams structure PEM or DER
     encoded

     PARAMS_DATA_SIZE: holds the size of params_data (and will be
     replaced by the actual size of parameters)

     This function will export the given dh parameters to a PKCS3
     DHParams structure.  This is the format generated by "openssl
     dhparam" tool.  If the buffer provided is not long enough to hold
     the output, then GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.

     If the structure is PEM encoded, it will have a header of "BEGIN DH
     PARAMETERS".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_dh_params_export_raw
---------------------------

 -- Function: int gnutls_dh_params_export_raw (gnutls_dh_params_t
          PARAMS, gnutls_datum_t * PRIME, gnutls_datum_t * GENERATOR,
          unsigned int * BITS)
     PARAMS: Holds the DH parameters

     PRIME: will hold the new prime

     GENERATOR: will hold the new generator

     BITS: if non null will hold the secret key's number of bits

     This function will export the pair of prime and generator for use
     in the Diffie-Hellman key exchange.  The new parameters will be
     allocated using 'gnutls_malloc()' and will be stored in the
     appropriate datum.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_dh_params_generate2
--------------------------

 -- Function: int gnutls_dh_params_generate2 (gnutls_dh_params_t
          DPARAMS, unsigned int BITS)
     DPARAMS: Is the structure that the DH parameters will be stored

     BITS: is the prime's number of bits

     This function will generate a new pair of prime and generator for
     use in the Diffie-Hellman key exchange.  The new parameters will be
     allocated using 'gnutls_malloc()' and will be stored in the
     appropriate datum.  This function is normally slow.

     Do not set the number of bits directly, use
     'gnutls_sec_param_to_pk_bits()' to get bits for 'GNUTLS_PK_DSA' .
     Also note that the DH parameters are only useful to servers.  Since
     clients use the parameters sent by the server, it's of no use to
     call this in client side.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_dh_params_import_pkcs3
-----------------------------

 -- Function: int gnutls_dh_params_import_pkcs3 (gnutls_dh_params_t
          PARAMS, const gnutls_datum_t * PKCS3_PARAMS,
          gnutls_x509_crt_fmt_t FORMAT)
     PARAMS: A structure where the parameters will be copied to

     PKCS3_PARAMS: should contain a PKCS3 DHParams structure PEM or DER
     encoded

     FORMAT: the format of params.  PEM or DER.

     This function will extract the DHParams found in a PKCS3 formatted
     structure.  This is the format generated by "openssl dhparam" tool.

     If the structure is PEM encoded, it should have a header of "BEGIN
     DH PARAMETERS".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_dh_params_import_raw
---------------------------

 -- Function: int gnutls_dh_params_import_raw (gnutls_dh_params_t
          DH_PARAMS, const gnutls_datum_t * PRIME, const gnutls_datum_t
          * GENERATOR)
     DH_PARAMS: Is a structure that will hold the prime numbers

     PRIME: holds the new prime

     GENERATOR: holds the new generator

     This function will replace the pair of prime and generator for use
     in the Diffie-Hellman key exchange.  The new parameters should be
     stored in the appropriate gnutls_datum.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_dh_params_init
---------------------

 -- Function: int gnutls_dh_params_init (gnutls_dh_params_t * DH_PARAMS)
     DH_PARAMS: Is a structure that will hold the prime numbers

     This function will initialize the DH parameters structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_dh_set_prime_bits
------------------------

 -- Function: void gnutls_dh_set_prime_bits (gnutls_session_t SESSION,
          unsigned int BITS)
     SESSION: is a 'gnutls_session_t' structure.

     BITS: is the number of bits

     This function sets the number of bits, for use in a Diffie-Hellman
     key exchange.  This is used both in DH ephemeral and DH anonymous
     cipher suites.  This will set the minimum size of the prime that
     will be used for the handshake.

     In the client side it sets the minimum accepted number of bits.  If
     a server sends a prime with less bits than that
     'GNUTLS_E_DH_PRIME_UNACCEPTABLE' will be returned by the handshake.

     Note that this function will warn via the audit log for value that
     are believed to be weak.

     The function has no effect in server side.

     Note that since 3.1.7 this function is deprecated.  The minimum
     number of bits is set by the priority string level.  Also this
     function must be called after 'gnutls_priority_set_direct()' or the
     set value may be overridden by the selected priority options.

gnutls_digest_get_id
--------------------

 -- Function: gnutls_digest_algorithm_t gnutls_digest_get_id (const char
          * NAME)
     NAME: is a digest algorithm name

     Convert a string to a 'gnutls_digest_algorithm_t' value.  The names
     are compared in a case insensitive way.

     *Returns:* a 'gnutls_digest_algorithm_t' id of the specified MAC
     algorithm string, or 'GNUTLS_DIG_UNKNOWN' on failures.

gnutls_digest_get_name
----------------------

 -- Function: const char * gnutls_digest_get_name
          (gnutls_digest_algorithm_t ALGORITHM)
     ALGORITHM: is a digest algorithm

     Convert a 'gnutls_digest_algorithm_t' value to a string.

     *Returns:* a string that contains the name of the specified digest
     algorithm, or 'NULL' .

gnutls_digest_list
------------------

 -- Function: const gnutls_digest_algorithm_t * gnutls_digest_list (
          VOID)

     Get a list of hash (digest) algorithms supported by GnuTLS.

     This function is not thread safe.

     *Returns:* Return a (0)-terminated list of
     'gnutls_digest_algorithm_t' integers indicating the available
     digests.

gnutls_ecc_curve_get
--------------------

 -- Function: gnutls_ecc_curve_t gnutls_ecc_curve_get (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Returns the currently used elliptic curve.  Only valid when using
     an elliptic curve ciphersuite.

     *Returns:* the currently used curve, a 'gnutls_ecc_curve_t' type.

     *Since:* 3.0

gnutls_ecc_curve_get_name
-------------------------

 -- Function: const char * gnutls_ecc_curve_get_name (gnutls_ecc_curve_t
          CURVE)
     CURVE: is an ECC curve

     Convert a 'gnutls_ecc_curve_t' value to a string.

     *Returns:* a string that contains the name of the specified curve
     or 'NULL' .

     *Since:* 3.0

gnutls_ecc_curve_get_size
-------------------------

 -- Function: int gnutls_ecc_curve_get_size (gnutls_ecc_curve_t CURVE)
     CURVE: is an ECC curve

     Returns the size in bytes of the curve.

     *Returns:* a the size or (0).

     *Since:* 3.0

gnutls_ecc_curve_list
---------------------

 -- Function: const gnutls_ecc_curve_t * gnutls_ecc_curve_list ( VOID)

     Get the list of supported elliptic curves.

     This function is not thread safe.

     *Returns:* Return a (0)-terminated list of 'gnutls_ecc_curve_t'
     integers indicating the available curves.

gnutls_error_is_fatal
---------------------

 -- Function: int gnutls_error_is_fatal (int ERROR)
     ERROR: is a GnuTLS error code, a negative error code

     If a GnuTLS function returns a negative error code you may feed
     that value to this function to see if the error condition is fatal
     to a TLS session (i.e., must be terminated).

     Note that you may also want to check the error code manually, since
     some non-fatal errors to the protocol (such as a warning alert or a
     rehandshake request) may be fatal for your program.

     This function is only useful if you are dealing with errors from
     functions that relate to a TLS session (e.g., record layer or
     handshake layer handling functions).

     *Returns:* Non-zero value on fatal errors or zero on non-fatal.

gnutls_error_to_alert
---------------------

 -- Function: int gnutls_error_to_alert (int ERR, int * LEVEL)
     ERR: is a negative integer

     LEVEL: the alert level will be stored there

     Get an alert depending on the error code returned by a gnutls
     function.  All alerts sent by this function should be considered
     fatal.  The only exception is when 'err' is 'GNUTLS_E_REHANDSHAKE'
     , where a warning alert should be sent to the peer indicating that
     no renegotiation will be performed.

     If there is no mapping to a valid alert the alert to indicate
     internal error is returned.

     *Returns:* the alert code to use for a particular error code.

gnutls_est_record_overhead_size
-------------------------------

 -- Function: size_t gnutls_est_record_overhead_size (gnutls_protocol_t
          VERSION, gnutls_cipher_algorithm_t CIPHER,
          gnutls_mac_algorithm_t MAC, gnutls_compression_method_t COMP,
          unsigned int FLAGS)
     VERSION: is a 'gnutls_protocol_t' value

     CIPHER: is a 'gnutls_cipher_algorithm_t' value

     MAC: is a 'gnutls_mac_algorithm_t' value

     COMP: is a 'gnutls_compression_method_t' value

     FLAGS: must be zero

     This function will return the set size in bytes of the overhead due
     to TLS (or DTLS) per record.

     Note that this function may provide inacurate values when TLS
     extensions that modify the record format are negotiated.  In these
     cases a more accurate value can be obtained using
     'gnutls_record_overhead_size()' after a completed handshake.

     *Since:* 3.2.2

gnutls_fingerprint
------------------

 -- Function: int gnutls_fingerprint (gnutls_digest_algorithm_t ALGO,
          const gnutls_datum_t * DATA, void * RESULT, size_t *
          RESULT_SIZE)
     ALGO: is a digest algorithm

     DATA: is the data

     RESULT: is the place where the result will be copied (may be null).

     RESULT_SIZE: should hold the size of the result.  The actual size
     of the returned result will also be copied there.

     This function will calculate a fingerprint (actually a hash), of
     the given data.  The result is not printable data.  You should
     convert it to hex, or to something else printable.

     This is the usual way to calculate a fingerprint of an X.509 DER
     encoded certificate.  Note however that the fingerprint of an
     OpenPGP certificate is not just a hash and cannot be calculated
     with this function.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_fips140_mode_enabled
---------------------------

 -- Function: int gnutls_fips140_mode_enabled ( VOID)

     Checks whether this library is in FIPS140 mode.

     *Returns:* return non-zero if true or zero if false.

     *Since:* 3.3.0

gnutls_global_deinit
--------------------

 -- Function: void gnutls_global_deinit ( VOID)

     This function deinitializes the global data, that were initialized
     using 'gnutls_global_init()' .

gnutls_global_init
------------------

 -- Function: int gnutls_global_init ( VOID)

     This function performs any required precalculations, detects the
     supported CPU capabilities and initializes the underlying
     cryptographic backend.  In order to free any resources taken by
     this call you should 'gnutls_global_deinit()' when gnutls usage is
     no longer needed.

     This function increments a global counter, so that
     'gnutls_global_deinit()' only releases resources when it has been
     called as many times as 'gnutls_global_init()' .  This is useful
     when GnuTLS is used by more than one library in an application.
     This function can be called many times, but will only do something
     the first time.

     Since GnuTLS 3.3.0 this function is only required in systems that
     do not support library constructors and static linking.  This
     function also became thread safe.

     A subsequent call of this function if the initial has failed will
     return the same error code.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_global_set_audit_log_function
------------------------------------

 -- Function: void gnutls_global_set_audit_log_function
          (gnutls_audit_log_func LOG_FUNC)
     LOG_FUNC: it is the audit log function

     This is the function to set the audit logging function.  This is a
     function to report important issues, such as possible attacks in
     the protocol.  This is different from
     'gnutls_global_set_log_function()' because it will report also
     session-specific events.  The session parameter will be null if
     there is no corresponding TLS session.

     'gnutls_audit_log_func' is of the form, void
     (*gnutls_audit_log_func)( gnutls_session_t, const char*);

     *Since:* 3.0

gnutls_global_set_log_function
------------------------------

 -- Function: void gnutls_global_set_log_function (gnutls_log_func
          LOG_FUNC)
     LOG_FUNC: it's a log function

     This is the function where you set the logging function gnutls is
     going to use.  This function only accepts a character array.
     Normally you may not use this function since it is only used for
     debugging purposes.

     'gnutls_log_func' is of the form, void (*gnutls_log_func)( int
     level, const char*);

gnutls_global_set_log_level
---------------------------

 -- Function: void gnutls_global_set_log_level (int LEVEL)
     LEVEL: it's an integer from 0 to 99.

     This is the function that allows you to set the log level.  The
     level is an integer between 0 and 9.  Higher values mean more
     verbosity.  The default value is 0.  Larger values should only be
     used with care, since they may reveal sensitive information.

     Use a log level over 10 to enable all debugging options.

gnutls_global_set_mutex
-----------------------

 -- Function: void gnutls_global_set_mutex (mutex_init_func INIT,
          mutex_deinit_func DEINIT, mutex_lock_func LOCK,
          mutex_unlock_func UNLOCK)
     INIT: mutex initialization function

     DEINIT: mutex deinitialization function

     LOCK: mutex locking function

     UNLOCK: mutex unlocking function

     With this function you are allowed to override the default mutex
     locks used in some parts of gnutls and dependent libraries.  This
     function should be used if you have complete control of your
     program and libraries.  Do not call this function from a library,
     or preferrably from any application unless really needed to.
     GnuTLS will use the appropriate locks for the running system.

     This function must be called prior to any other gnutls function.

     *Since:* 2.12.0

gnutls_global_set_time_function
-------------------------------

 -- Function: void gnutls_global_set_time_function (gnutls_time_func
          TIME_FUNC)
     TIME_FUNC: it's the system time function, a 'gnutls_time_func()'
     callback.

     This is the function where you can override the default system time
     function.  The application provided function should behave the same
     as the standard function.

     *Since:* 2.12.0

gnutls_handshake
----------------

 -- Function: int gnutls_handshake (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function does the handshake of the TLS/SSL protocol, and
     initializes the TLS connection.

     This function will fail if any problem is encountered, and will
     return a negative error code.  In case of a client, if the client
     has asked to resume a session, but the server couldn't, then a full
     handshake will be performed.

     The non-fatal errors expected by this function are:
     'GNUTLS_E_INTERRUPTED' , 'GNUTLS_E_AGAIN' ,
     'GNUTLS_E_WARNING_ALERT_RECEIVED' , and
     'GNUTLS_E_GOT_APPLICATION_DATA' , the latter only in a case of
     rehandshake.

     The former two interrupt the handshake procedure due to the lower
     layer being interrupted, and the latter because of an alert that
     may be sent by a server (it is always a good idea to check any
     received alerts).  On these errors call this function again, until
     it returns 0; cf.  'gnutls_record_get_direction()' and
     'gnutls_error_is_fatal()' .  In DTLS sessions the non-fatal error
     'GNUTLS_E_LARGE_PACKET' is also possible, and indicates that the
     MTU should be adjusted.

     If this function is called by a server after a rehandshake request
     then 'GNUTLS_E_GOT_APPLICATION_DATA' or
     'GNUTLS_E_WARNING_ALERT_RECEIVED' may be returned.  Note that these
     are non fatal errors, only in the specific case of a rehandshake.
     Their meaning is that the client rejected the rehandshake request
     or in the case of 'GNUTLS_E_GOT_APPLICATION_DATA' it could also
     mean that some data were pending.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

gnutls_handshake_description_get_name
-------------------------------------

 -- Function: const char * gnutls_handshake_description_get_name
          (gnutls_handshake_description_t TYPE)
     TYPE: is a handshake message description

     Convert a 'gnutls_handshake_description_t' value to a string.

     *Returns:* a string that contains the name of the specified
     handshake message or 'NULL' .

gnutls_handshake_get_last_in
----------------------------

 -- Function: gnutls_handshake_description_t
          gnutls_handshake_get_last_in (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function is only useful to check where the last performed
     handshake failed.  If the previous handshake succeed or was not
     performed at all then no meaningful value will be returned.

     Check 'gnutls_handshake_description_t' in gnutls.h for the
     available handshake descriptions.

     *Returns:* the last handshake message type received, a
     'gnutls_handshake_description_t' .

gnutls_handshake_get_last_out
-----------------------------

 -- Function: gnutls_handshake_description_t
          gnutls_handshake_get_last_out (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function is only useful to check where the last performed
     handshake failed.  If the previous handshake succeed or was not
     performed at all then no meaningful value will be returned.

     Check 'gnutls_handshake_description_t' in gnutls.h for the
     available handshake descriptions.

     *Returns:* the last handshake message type sent, a
     'gnutls_handshake_description_t' .

gnutls_handshake_set_hook_function
----------------------------------

 -- Function: void gnutls_handshake_set_hook_function (gnutls_session_t
          SESSION, unsigned int HTYPE, int POST,
          gnutls_handshake_hook_func FUNC)
     SESSION: is a 'gnutls_session_t' structure

     HTYPE: the 'gnutls_handshake_description_t' of the message to hook
     at

     POST: 'GNUTLS_HOOK_' * depending on when the hook function should
     be called

     FUNC: is the function to be called

     This function will set a callback to be called after or before the
     specified handshake message has been received or generated.  This
     is a generalization of
     'gnutls_handshake_set_post_client_hello_function()' .

     To call the hook function prior to the message being sent/generated
     use 'GNUTLS_HOOK_PRE' as 'post' parameter, 'GNUTLS_HOOK_POST' to
     call after, and 'GNUTLS_HOOK_BOTH' for both cases.

     This callback must return 0 on success or a gnutls error code to
     terminate the handshake.

     Note to hook at all handshake messages use an 'htype' of
     'GNUTLS_HANDSHAKE_ANY' .

     *Warning:* You should not use this function to terminate the
     handshake based on client input unless you know what you are doing.
     Before the handshake is finished there is no way to know if there
     is a man-in-the-middle attack being performed.

gnutls_handshake_set_max_packet_length
--------------------------------------

 -- Function: void gnutls_handshake_set_max_packet_length
          (gnutls_session_t SESSION, size_t MAX)
     SESSION: is a 'gnutls_session_t' structure.

     MAX: is the maximum number.

     This function will set the maximum size of all handshake messages.
     Handshakes over this size are rejected with
     'GNUTLS_E_HANDSHAKE_TOO_LARGE' error code.  The default value is
     128kb which is typically large enough.  Set this to 0 if you do not
     want to set an upper limit.

     The reason for restricting the handshake message sizes are to limit
     Denial of Service attacks.

     Note that the maximum handshake size was increased to 128kb from
     48kb in GnuTLS 3.3.25.

gnutls_handshake_set_post_client_hello_function
-----------------------------------------------

 -- Function: void gnutls_handshake_set_post_client_hello_function
          (gnutls_session_t SESSION,
          gnutls_handshake_post_client_hello_func FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     FUNC: is the function to be called

     This function will set a callback to be called after the client
     hello has been received (callback valid in server side only).  This
     allows the server to adjust settings based on received extensions.

     Those settings could be ciphersuites, requesting certificate, or
     anything else except for version negotiation (this is done before
     the hello message is parsed).

     This callback must return 0 on success or a gnutls error code to
     terminate the handshake.

     Since GnuTLS 3.3.5 the callback is allowed to return
     'GNUTLS_E_AGAIN' or 'GNUTLS_E_INTERRUPTED' to put the handshake on
     hold.  In that case 'gnutls_handshake()' will return
     'GNUTLS_E_INTERRUPTED' and can be resumed when needed.

     *Warning:* You should not use this function to terminate the
     handshake based on client input unless you know what you are doing.
     Before the handshake is finished there is no way to know if there
     is a man-in-the-middle attack being performed.

gnutls_handshake_set_private_extensions
---------------------------------------

 -- Function: void gnutls_handshake_set_private_extensions
          (gnutls_session_t SESSION, int ALLOW)
     SESSION: is a 'gnutls_session_t' structure.

     ALLOW: is an integer (0 or 1)

     This function will enable or disable the use of private cipher
     suites (the ones that start with 0xFF). By default or if 'allow' is
     0 then these cipher suites will not be advertised nor used.

     Currently GnuTLS does not include such cipher-suites or compression
     algorithms.

     Enabling the private ciphersuites when talking to other than gnutls
     servers and clients may cause interoperability problems.

gnutls_handshake_set_random
---------------------------

 -- Function: int gnutls_handshake_set_random (gnutls_session_t SESSION,
          const gnutls_datum_t * RANDOM)
     SESSION: is a 'gnutls_session_t' structure.

     RANDOM: a random value of 32-bytes

     This function will explicitly set the server or client hello random
     value in the subsequent TLS handshake.  The random value should be
     a 32-byte value.

     Note that this function should not normally be used as gnutls will
     select automatically a random value for the handshake.

     This function should not be used when resuming a session.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

     Since 3.1.9

gnutls_handshake_set_timeout
----------------------------

 -- Function: void gnutls_handshake_set_timeout (gnutls_session_t
          SESSION, unsigned int MS)
     SESSION: is a 'gnutls_session_t' structure.

     MS: is a timeout value in milliseconds

     This function sets the timeout for the handshake process to the
     provided value.  Use an 'ms' value of zero to disable timeout, or
     'GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT' for a reasonable default value.

     *Since:* 3.1.0

gnutls_heartbeat_allowed
------------------------

 -- Function: int gnutls_heartbeat_allowed (gnutls_session_t SESSION,
          unsigned int TYPE)
     SESSION: is a 'gnutls_session_t' structure.

     TYPE: one of 'GNUTLS_HB_LOCAL_ALLOWED_TO_SEND' and
     'GNUTLS_HB_PEER_ALLOWED_TO_SEND'

     This function will check whether heartbeats are allowed to be sent
     or received in this session.

     *Returns:* Non zero if heartbeats are allowed.

     *Since:* 3.1.2

gnutls_heartbeat_enable
-----------------------

 -- Function: void gnutls_heartbeat_enable (gnutls_session_t SESSION,
          unsigned int TYPE)
     SESSION: is a 'gnutls_session_t' structure.

     TYPE: one of the GNUTLS_HB_* flags

     If this function is called with the
     'GNUTLS_HB_PEER_ALLOWED_TO_SEND' 'type' , GnuTLS will allow
     heartbeat messages to be received.  Moreover it also request the
     peer to accept heartbeat messages.

     If the 'type' used is 'GNUTLS_HB_LOCAL_ALLOWED_TO_SEND' , then the
     peer will be asked to accept heartbeat messages but not send ones.

     The function 'gnutls_heartbeat_allowed()' can be used to test
     Whether locally generated heartbeat messages can be accepted by the
     peer.

     *Since:* 3.1.2

gnutls_heartbeat_get_timeout
----------------------------

 -- Function: unsigned int gnutls_heartbeat_get_timeout
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function will return the milliseconds remaining for a
     retransmission of the previously sent ping message.  This function
     is useful when ping is used in non-blocking mode, to estimate when
     to call 'gnutls_heartbeat_ping()' if no packets have been received.

     *Returns:* the remaining time in milliseconds.

     *Since:* 3.1.2

gnutls_heartbeat_ping
---------------------

 -- Function: int gnutls_heartbeat_ping (gnutls_session_t SESSION,
          size_t DATA_SIZE, unsigned int MAX_TRIES, unsigned int FLAGS)
     SESSION: is a 'gnutls_session_t' structure.

     DATA_SIZE: is the length of the ping payload.

     MAX_TRIES: if flags is 'GNUTLS_HEARTBEAT_WAIT' then this sets the
     number of retransmissions.  Use zero for indefinite (until
     timeout).

     FLAGS: if 'GNUTLS_HEARTBEAT_WAIT' then wait for pong or timeout
     instead of returning immediately.

     This function sends a ping to the peer.  If the 'flags' is set to
     'GNUTLS_HEARTBEAT_WAIT' then it waits for a reply from the peer.

     Note that it is highly recommended to use this function with the
     flag 'GNUTLS_HEARTBEAT_WAIT' , or you need to handle
     retransmissions and timeouts manually.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

     *Since:* 3.1.2

gnutls_heartbeat_pong
---------------------

 -- Function: int gnutls_heartbeat_pong (gnutls_session_t SESSION,
          unsigned int FLAGS)
     SESSION: is a 'gnutls_session_t' structure.

     FLAGS: should be zero

     This function replies to a ping by sending a pong to the peer.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

     *Since:* 3.1.2

gnutls_heartbeat_set_timeouts
-----------------------------

 -- Function: void gnutls_heartbeat_set_timeouts (gnutls_session_t
          SESSION, unsigned int RETRANS_TIMEOUT, unsigned int
          TOTAL_TIMEOUT)
     SESSION: is a 'gnutls_session_t' structure.

     RETRANS_TIMEOUT: The time at which a retransmission will occur in
     milliseconds

     TOTAL_TIMEOUT: The time at which the connection will be aborted, in
     milliseconds.

     This function will override the timeouts for the DTLS heartbeat
     protocol.  The retransmission timeout is the time after which a
     message from the peer is not received, the previous request will be
     retransmitted.  The total timeout is the time after which the
     handshake will be aborted with 'GNUTLS_E_TIMEDOUT' .

     If the retransmission timeout is zero then the handshake will
     operate in a non-blocking way, i.e., return 'GNUTLS_E_AGAIN' .

     *Since:* 3.1.2

gnutls_hex2bin
--------------

 -- Function: int gnutls_hex2bin (const char * HEX_DATA, size_t
          HEX_SIZE, void * BIN_DATA, size_t * BIN_SIZE)
     HEX_DATA: string with data in hex format

     HEX_SIZE: size of hex data

     BIN_DATA: output array with binary data

     BIN_SIZE: when calling should hold maximum size of 'bin_data' , on
     return will hold actual length of 'bin_data' .

     Convert a buffer with hex data to binary data.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

     *Since:* 2.4.0

gnutls_hex_decode
-----------------

 -- Function: int gnutls_hex_decode (const gnutls_datum_t * HEX_DATA,
          void * RESULT, size_t * RESULT_SIZE)
     HEX_DATA: contain the encoded data

     RESULT: the place where decoded data will be copied

     RESULT_SIZE: holds the size of the result

     This function will decode the given encoded data, using the hex
     encoding used by PSK password files.

     Note that hex_data should be null terminated.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the buffer given is
     not long enough, or 0 on success.

gnutls_hex_encode
-----------------

 -- Function: int gnutls_hex_encode (const gnutls_datum_t * DATA, char *
          RESULT, size_t * RESULT_SIZE)
     DATA: contain the raw data

     RESULT: the place where hex data will be copied

     RESULT_SIZE: holds the size of the result

     This function will convert the given data to printable data, using
     the hex encoding, as used in the PSK password files.

     Note that the size of the result includes the null terminator.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the buffer given is
     not long enough, or 0 on success.

gnutls_init
-----------

 -- Function: int gnutls_init (gnutls_session_t * SESSION, unsigned int
          FLAGS)
     SESSION: is a pointer to a 'gnutls_session_t' structure.

     FLAGS: indicate if this session is to be used for server or client.

     This function initializes the current session to null.  Every
     session must be initialized before use, so internal structures can
     be allocated.  This function allocates structures which can only be
     free'd by calling 'gnutls_deinit()' .  Returns 'GNUTLS_E_SUCCESS'
     (0) on success.

     'flags' can be one of 'GNUTLS_CLIENT' and 'GNUTLS_SERVER' .  For a
     DTLS entity, the flags 'GNUTLS_DATAGRAM' and 'GNUTLS_NONBLOCK' are
     also available.  The latter flag will enable a non-blocking
     operation of the DTLS timers.

     The flag 'GNUTLS_NO_REPLAY_PROTECTION' will disable any replay
     protection in DTLS mode.  That must only used when replay
     protection is achieved using other means.

     Note that since version 3.1.2 this function enables some common TLS
     extensions such as session tickets and OCSP certificate status
     request in client side by default.  To prevent that use the
     'GNUTLS_NO_EXTENSIONS' flag.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_key_generate
-------------------

 -- Function: int gnutls_key_generate (gnutls_datum_t * KEY, unsigned
          int KEY_SIZE)
     KEY: is a pointer to a 'gnutls_datum_t' which will contain a newly
     created key.

     KEY_SIZE: The number of bytes of the key.

     Generates a random key of 'key_size' bytes.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

     *Since:* 3.0

gnutls_kx_get
-------------

 -- Function: gnutls_kx_algorithm_t gnutls_kx_get (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get currently used key exchange algorithm.

     *Returns:* the key exchange algorithm used in the last handshake, a
     'gnutls_kx_algorithm_t' value.

gnutls_kx_get_id
----------------

 -- Function: gnutls_kx_algorithm_t gnutls_kx_get_id (const char * NAME)
     NAME: is a KX name

     Convert a string to a 'gnutls_kx_algorithm_t' value.  The names are
     compared in a case insensitive way.

     *Returns:* an id of the specified KX algorithm, or
     'GNUTLS_KX_UNKNOWN' on error.

gnutls_kx_get_name
------------------

 -- Function: const char * gnutls_kx_get_name (gnutls_kx_algorithm_t
          ALGORITHM)
     ALGORITHM: is a key exchange algorithm

     Convert a 'gnutls_kx_algorithm_t' value to a string.

     *Returns:* a pointer to a string that contains the name of the
     specified key exchange algorithm, or 'NULL' .

gnutls_kx_list
--------------

 -- Function: const gnutls_kx_algorithm_t * gnutls_kx_list ( VOID)

     Get a list of supported key exchange algorithms.

     This function is not thread safe.

     *Returns:* a (0)-terminated list of 'gnutls_kx_algorithm_t'
     integers indicating the available key exchange algorithms.

gnutls_load_file
----------------

 -- Function: int gnutls_load_file (const char * FILENAME,
          gnutls_datum_t * DATA)
     FILENAME: the name of the file to load

     DATA: Where the file will be stored

     This function will load a file into a datum.  The data are zero
     terminated but the terminating null is not included in length.  The
     returned data are allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

     Since 3.1.0

gnutls_mac_get
--------------

 -- Function: gnutls_mac_algorithm_t gnutls_mac_get (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get currently used MAC algorithm.

     *Returns:* the currently used mac algorithm, a
     'gnutls_mac_algorithm_t' value.

gnutls_mac_get_id
-----------------

 -- Function: gnutls_mac_algorithm_t gnutls_mac_get_id (const char *
          NAME)
     NAME: is a MAC algorithm name

     Convert a string to a 'gnutls_mac_algorithm_t' value.  The names
     are compared in a case insensitive way.

     *Returns:* a 'gnutls_mac_algorithm_t' id of the specified MAC
     algorithm string, or 'GNUTLS_MAC_UNKNOWN' on failures.

gnutls_mac_get_key_size
-----------------------

 -- Function: size_t gnutls_mac_get_key_size (gnutls_mac_algorithm_t
          ALGORITHM)
     ALGORITHM: is an encryption algorithm

     Returns the size of the MAC key used in TLS.

     *Returns:* length (in bytes) of the given MAC key size, or 0 if the
     given MAC algorithm is invalid.

gnutls_mac_get_name
-------------------

 -- Function: const char * gnutls_mac_get_name (gnutls_mac_algorithm_t
          ALGORITHM)
     ALGORITHM: is a MAC algorithm

     Convert a 'gnutls_mac_algorithm_t' value to a string.

     *Returns:* a string that contains the name of the specified MAC
     algorithm, or 'NULL' .

gnutls_mac_list
---------------

 -- Function: const gnutls_mac_algorithm_t * gnutls_mac_list ( VOID)

     Get a list of hash algorithms for use as MACs.  Note that not
     necessarily all MACs are supported in TLS cipher suites.  This
     function is not thread safe.

     *Returns:* Return a (0)-terminated list of 'gnutls_mac_algorithm_t'
     integers indicating the available MACs.

gnutls_ocsp_status_request_enable_client
----------------------------------------

 -- Function: int gnutls_ocsp_status_request_enable_client
          (gnutls_session_t SESSION, gnutls_datum_t * RESPONDER_ID,
          size_t RESPONDER_ID_SIZE, gnutls_datum_t * EXTENSIONS)
     SESSION: is a 'gnutls_session_t' structure.

     RESPONDER_ID: array with 'gnutls_datum_t' with DER data of
     responder id

     RESPONDER_ID_SIZE: number of members in 'responder_id' array

     EXTENSIONS: a 'gnutls_datum_t' with DER encoded OCSP extensions

     This function is to be used by clients to request OCSP response
     from the server, using the "status_request" TLS extension.  Only
     OCSP status type is supported.

     The 'responder_id' array, its containing elements as well as the
     data of 'extensions' , must be allocated using 'gnutls_malloc()' .
     They will be deinitialized on session cleanup.

     Due to the difficult semantics of the 'responder_id' and
     'extensions' parameters, it is recommended to only call this
     function with these parameters set to 'NULL' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     *Since:* 3.1.3

gnutls_ocsp_status_request_get
------------------------------

 -- Function: int gnutls_ocsp_status_request_get (gnutls_session_t
          SESSION, gnutls_datum_t * RESPONSE)
     SESSION: is a 'gnutls_session_t' structure.

     RESPONSE: a 'gnutls_datum_t' with DER encoded OCSP response

     This function returns the OCSP status response received from the
     TLS server.  The 'response' should be treated as constant.  If no
     OCSP response is available then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     *Since:* 3.1.3

gnutls_ocsp_status_request_is_checked
-------------------------------------

 -- Function: int gnutls_ocsp_status_request_is_checked
          (gnutls_session_t SESSION, unsigned int FLAGS)
     SESSION: is a gnutls session

     FLAGS: should be zero

     Check whether an OCSP status response was included in the handshake
     and whether it was checked and valid (not too old or superseded).
     This is a helper function when needing to decide whether to perform
     an OCSP validity check on the peer's certificate.  Must be called
     after 'gnutls_certificate_verify_peers3()' is called.

     *Returns:* non zero it was valid, or a zero if it wasn't sent, or
     sent and was invalid.

gnutls_openpgp_send_cert
------------------------

 -- Function: void gnutls_openpgp_send_cert (gnutls_session_t SESSION,
          gnutls_openpgp_crt_status_t STATUS)
     SESSION: is a pointer to a 'gnutls_session_t' structure.

     STATUS: is one of GNUTLS_OPENPGP_CERT, or
     GNUTLS_OPENPGP_CERT_FINGERPRINT

     This function will order gnutls to send the key fingerprint instead
     of the key in the initial handshake procedure.  This should be used
     with care and only when there is indication or knowledge that the
     server can obtain the client's key.

gnutls_packet_deinit
--------------------

 -- Function: void gnutls_packet_deinit (gnutls_packet_t PACKET)
     PACKET: is a pointer to a 'gnutls_packet_st' structure.

     This function will deinitialize all data associated with the
     received packet.

     *Since:* 3.3.5

gnutls_packet_get
-----------------

 -- Function: void gnutls_packet_get (gnutls_packet_t PACKET,
          gnutls_datum_t * DATA, unsigned char * SEQUENCE)
     PACKET: is a 'gnutls_packet_t' structure.

     DATA: will contain the data present in the 'packet' structure (may
     be 'NULL' )

     SEQUENCE: the 8-bytes of the packet sequence number (may be 'NULL'
     )

     This function returns the data and sequence number associated with
     the received packet.

     *Since:* 3.3.5

gnutls_pem_base64_decode
------------------------

 -- Function: int gnutls_pem_base64_decode (const char * HEADER, const
          gnutls_datum_t * B64_DATA, unsigned char * RESULT, size_t *
          RESULT_SIZE)
     HEADER: A null terminated string with the PEM header (eg.
     CERTIFICATE)

     B64_DATA: contain the encoded data

     RESULT: the place where decoded data will be copied

     RESULT_SIZE: holds the size of the result

     This function will decode the given encoded data.  If the header
     given is non null this function will search for "---BEGIN header"
     and decode only this part.  Otherwise it will decode the first PEM
     packet found.

     *Returns:* On success 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_SHORT_MEMORY_BUFFER' is returned if the buffer given is
     not long enough, or 0 on success.

gnutls_pem_base64_decode_alloc
------------------------------

 -- Function: int gnutls_pem_base64_decode_alloc (const char * HEADER,
          const gnutls_datum_t * B64_DATA, gnutls_datum_t * RESULT)
     HEADER: The PEM header (eg.  CERTIFICATE)

     B64_DATA: contains the encoded data

     RESULT: the place where decoded data lie

     This function will decode the given encoded data.  The decoded data
     will be allocated, and stored into result.  If the header given is
     non null this function will search for "---BEGIN header" and decode
     only this part.  Otherwise it will decode the first PEM packet
     found.

     You should use 'gnutls_free()' to free the returned data.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_pem_base64_encode
------------------------

 -- Function: int gnutls_pem_base64_encode (const char * MSG, const
          gnutls_datum_t * DATA, char * RESULT, size_t * RESULT_SIZE)
     MSG: is a message to be put in the header

     DATA: contain the raw data

     RESULT: the place where base64 data will be copied

     RESULT_SIZE: holds the size of the result

     This function will convert the given data to printable data, using
     the base64 encoding.  This is the encoding used in PEM messages.

     The output string will be null terminated, although the size will
     not include the terminating null.

     *Returns:* On success 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_SHORT_MEMORY_BUFFER' is returned if the buffer given is
     not long enough, or 0 on success.

gnutls_pem_base64_encode_alloc
------------------------------

 -- Function: int gnutls_pem_base64_encode_alloc (const char * MSG,
          const gnutls_datum_t * DATA, gnutls_datum_t * RESULT)
     MSG: is a message to be put in the encoded header

     DATA: contains the raw data

     RESULT: will hold the newly allocated encoded data

     This function will convert the given data to printable data, using
     the base64 encoding.  This is the encoding used in PEM messages.
     This function will allocate the required memory to hold the encoded
     data.

     You should use 'gnutls_free()' to free the returned data.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_perror
-------------

 -- Function: void gnutls_perror (int ERROR)
     ERROR: is a GnuTLS error code, a negative error code

     This function is like 'perror()' .  The only difference is that it
     accepts an error number returned by a gnutls function.

gnutls_pk_algorithm_get_name
----------------------------

 -- Function: const char * gnutls_pk_algorithm_get_name
          (gnutls_pk_algorithm_t ALGORITHM)
     ALGORITHM: is a pk algorithm

     Convert a 'gnutls_pk_algorithm_t' value to a string.

     *Returns:* a string that contains the name of the specified public
     key algorithm, or 'NULL' .

gnutls_pk_bits_to_sec_param
---------------------------

 -- Function: gnutls_sec_param_t gnutls_pk_bits_to_sec_param
          (gnutls_pk_algorithm_t ALGO, unsigned int BITS)
     ALGO: is a public key algorithm

     BITS: is the number of bits

     This is the inverse of 'gnutls_sec_param_to_pk_bits()' .  Given an
     algorithm and the number of bits, it will return the security
     parameter.  This is a rough indication.

     *Returns:* The security parameter.

     *Since:* 2.12.0

gnutls_pk_get_id
----------------

 -- Function: gnutls_pk_algorithm_t gnutls_pk_get_id (const char * NAME)
     NAME: is a string containing a public key algorithm name.

     Convert a string to a 'gnutls_pk_algorithm_t' value.  The names are
     compared in a case insensitive way.  For example,
     gnutls_pk_get_id("RSA") will return 'GNUTLS_PK_RSA' .

     *Returns:* a 'gnutls_pk_algorithm_t' id of the specified public key
     algorithm string, or 'GNUTLS_PK_UNKNOWN' on failures.

     *Since:* 2.6.0

gnutls_pk_get_name
------------------

 -- Function: const char * gnutls_pk_get_name (gnutls_pk_algorithm_t
          ALGORITHM)
     ALGORITHM: is a public key algorithm

     Convert a 'gnutls_pk_algorithm_t' value to a string.

     *Returns:* a pointer to a string that contains the name of the
     specified public key algorithm, or 'NULL' .

     *Since:* 2.6.0

gnutls_pk_list
--------------

 -- Function: const gnutls_pk_algorithm_t * gnutls_pk_list ( VOID)

     Get a list of supported public key algorithms.

     This function is not thread safe.

     *Returns:* a (0)-terminated list of 'gnutls_pk_algorithm_t'
     integers indicating the available ciphers.

     *Since:* 2.6.0

gnutls_pk_to_sign
-----------------

 -- Function: gnutls_sign_algorithm_t gnutls_pk_to_sign
          (gnutls_pk_algorithm_t PK, gnutls_digest_algorithm_t HASH)
     PK: is a public key algorithm

     HASH: a hash algorithm

     This function maps public key and hash algorithms combinations to
     signature algorithms.

     *Returns:* return a 'gnutls_sign_algorithm_t' value, or
     'GNUTLS_SIGN_UNKNOWN' on error.

gnutls_prf
----------

 -- Function: int gnutls_prf (gnutls_session_t SESSION, size_t
          LABEL_SIZE, const char * LABEL, int SERVER_RANDOM_FIRST,
          size_t EXTRA_SIZE, const char * EXTRA, size_t OUTSIZE, char *
          OUT)
     SESSION: is a 'gnutls_session_t' structure.

     LABEL_SIZE: length of the 'label' variable.

     LABEL: label used in PRF computation, typically a short string.

     SERVER_RANDOM_FIRST: non-zero if server random field should be
     first in seed

     EXTRA_SIZE: length of the 'extra' variable.

     EXTRA: optional extra data to seed the PRF with.

     OUTSIZE: size of pre-allocated output buffer to hold the output.

     OUT: pre-allocated buffer to hold the generated data.

     Applies the TLS Pseudo-Random-Function (PRF) on the master secret
     and the provided data, seeded with the client and server random
     fields.

     The output of this function is identical to RFC5705 extractor if
     'extra' and 'extra_size' are set to zero.  Otherwise, 'extra'
     should contain the context value prefixed by a two-byte length.

     The 'label' variable usually contains a string denoting the purpose
     for the generated data.  The 'server_random_first' indicates
     whether the client random field or the server random field should
     be first in the seed.  Non-zero indicates that the server random
     field is first, 0 that the client random field is first.

     The 'extra' variable can be used to add more data to the seed,
     after the random variables.  It can be used to make sure the
     generated output is strongly connected to some additional data
     (e.g., a string used in user authentication).

     The output is placed in 'out' , which must be pre-allocated.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_prf_raw
--------------

 -- Function: int gnutls_prf_raw (gnutls_session_t SESSION, size_t
          LABEL_SIZE, const char * LABEL, size_t SEED_SIZE, const char *
          SEED, size_t OUTSIZE, char * OUT)
     SESSION: is a 'gnutls_session_t' structure.

     LABEL_SIZE: length of the 'label' variable.

     LABEL: label used in PRF computation, typically a short string.

     SEED_SIZE: length of the 'seed' variable.

     SEED: optional extra data to seed the PRF with.

     OUTSIZE: size of pre-allocated output buffer to hold the output.

     OUT: pre-allocated buffer to hold the generated data.

     Apply the TLS Pseudo-Random-Function (PRF) on the master secret and
     the provided data.

     The 'label' variable usually contains a string denoting the purpose
     for the generated data.  The 'seed' usually contains data such as
     the client and server random, perhaps together with some additional
     data that is added to guarantee uniqueness of the output for a
     particular purpose.

     Because the output is not guaranteed to be unique for a particular
     session unless 'seed' includes the client random and server random
     fields (the PRF would output the same data on another connection
     resumed from the first one), it is not recommended to use this
     function directly.  The 'gnutls_prf()' function seeds the PRF with
     the client and server random fields directly, and is recommended if
     you want to generate pseudo random data unique for each session.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_priority_certificate_type_list
-------------------------------------

 -- Function: int gnutls_priority_certificate_type_list
          (gnutls_priority_t PCACHE, const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available certificate types in the priority
     structure.

     *Returns:* the number of certificate types, or an error code.

     *Since:* 3.0

gnutls_priority_cipher_list
---------------------------

 -- Function: int gnutls_priority_cipher_list (gnutls_priority_t PCACHE,
          const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available ciphers in the priority structure.

     *Returns:* the number of curves, or an error code.

     *Since:* 3.2.3

gnutls_priority_compression_list
--------------------------------

 -- Function: int gnutls_priority_compression_list (gnutls_priority_t
          PCACHE, const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available compression method in the priority
     structure.

     *Returns:* the number of methods, or an error code.

     *Since:* 3.0

gnutls_priority_deinit
----------------------

 -- Function: void gnutls_priority_deinit (gnutls_priority_t
          PRIORITY_CACHE)
     PRIORITY_CACHE: is a 'gnutls_prioritity_t' structure.

     Deinitializes the priority cache.

gnutls_priority_ecc_curve_list
------------------------------

 -- Function: int gnutls_priority_ecc_curve_list (gnutls_priority_t
          PCACHE, const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available elliptic curves in the priority structure.

     *Returns:* the number of curves, or an error code.

     *Since:* 3.0

gnutls_priority_get_cipher_suite_index
--------------------------------------

 -- Function: int gnutls_priority_get_cipher_suite_index
          (gnutls_priority_t PCACHE, unsigned int IDX, unsigned int *
          SIDX)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     IDX: is an index number.

     SIDX: internal index of cipher suite to get information about.

     Provides the internal ciphersuite index to be used with
     'gnutls_cipher_suite_info()' .  The index 'idx' provided is an
     index kept at the priorities structure.  It might be that a valid
     priorities index does not correspond to a ciphersuite and in that
     case 'GNUTLS_E_UNKNOWN_CIPHER_SUITE' will be returned.  Once the
     last available index is crossed then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Returns:* On success it returns 'GNUTLS_E_SUCCESS' (0), or a
     negative error value otherwise.

gnutls_priority_init
--------------------

 -- Function: int gnutls_priority_init (gnutls_priority_t *
          PRIORITY_CACHE, const char * PRIORITIES, const char **
          ERR_POS)
     PRIORITY_CACHE: is a 'gnutls_prioritity_t' structure.

     PRIORITIES: is a string describing priorities (may be 'NULL' )

     ERR_POS: In case of an error this will have the position in the
     string the error occurred

     Sets priorities for the ciphers, key exchange methods, macs and
     compression methods.

     The 'priorities' option allows you to specify a colon separated
     list of the cipher priorities to enable.  Some keywords are defined
     to provide quick access to common preferences.

     Unless there is a special need, use the "NORMAL" keyword to apply a
     reasonable security level, or "NORMAL:'COMPAT' " for compatibility.

     "PERFORMANCE" means all the "secure" ciphersuites are enabled,
     limited to 128 bit ciphers and sorted by terms of speed
     performance.

     "LEGACY" the NORMAL settings for GnuTLS 3.2.x or earlier.  There is
     no verification profile set, and the allowed DH primes are
     considered weak today.

     "NORMAL" means all "secure" ciphersuites.  The 256-bit ciphers are
     included as a fallback only.  The ciphers are sorted by security
     margin.

     "PFS" means all "secure" ciphersuites that support perfect forward
     secrecy.  The 256-bit ciphers are included as a fallback only.  The
     ciphers are sorted by security margin.

     "SECURE128" means all "secure" ciphersuites of security level
     128-bit or more.

     "SECURE192" means all "secure" ciphersuites of security level
     192-bit or more.

     "SUITEB128" means all the NSA SuiteB ciphersuites with security
     level of 128.

     "SUITEB192" means all the NSA SuiteB ciphersuites with security
     level of 192.

     "EXPORT" means all ciphersuites are enabled, including the
     low-security 40 bit ciphers.

     "NONE" means nothing is enabled.  This disables even protocols and
     compression methods.

     " 'KEYWORD' " The system administrator imposed settings.  The
     provided keywords will be expanded from a configuration-time
     provided file - default is: /etc/gnutls/default-priorities.  Any
     keywords that follow it, will be appended to the expanded string.
     If there is no system string, then the function will fail.  The
     system file should be formatted as "KEYWORD=VALUE", e.g.,
     "SYSTEM=NORMAL:-ARCFOUR-128".

     Special keywords are "!", "-" and "+".  "!"  or "-" appended with
     an algorithm will remove this algorithm.  "+" appended with an
     algorithm will add this algorithm.

     Check the GnuTLS manual section "Priority strings" for detailed
     information.

     *Examples:*
     "NONE:+VERS-TLS-ALL:+MAC-ALL:+RSA:+AES-128-CBC:+SIGN-ALL:+COMP-NULL"

     "NORMAL:-ARCFOUR-128" means normal ciphers except for ARCFOUR-128.

     "SECURE128:-VERS-SSL3.0:+COMP-DEFLATE" means that only secure
     ciphers are enabled, SSL3.0 is disabled, and libz compression
     enabled.

     "NONE:+VERS-TLS-ALL:+AES-128-CBC:+RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1",

     "NONE:+VERS-TLS-ALL:+AES-128-CBC:+ECDHE-RSA:+SHA1:+COMP-NULL:+SIGN-RSA-SHA1:+CURVE-SECP256R1",

     "SECURE256:+SECURE128",

     Note that "NORMAL:'COMPAT' " is the most compatible mode.

     A 'NULL' 'priorities' string indicates the default priorities to be
     used (this is available since GnuTLS 3.3.0).

     *Returns:* On syntax error 'GNUTLS_E_INVALID_REQUEST' is returned,
     'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_priority_kx_list
-----------------------

 -- Function: int gnutls_priority_kx_list (gnutls_priority_t PCACHE,
          const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available key exchange methods in the priority
     structure.

     *Returns:* the number of curves, or an error code.

     *Since:* 3.2.3

gnutls_priority_mac_list
------------------------

 -- Function: int gnutls_priority_mac_list (gnutls_priority_t PCACHE,
          const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available MAC algorithms in the priority structure.

     *Returns:* the number of curves, or an error code.

     *Since:* 3.2.3

gnutls_priority_protocol_list
-----------------------------

 -- Function: int gnutls_priority_protocol_list (gnutls_priority_t
          PCACHE, const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available TLS version numbers in the priority
     structure.

     *Returns:* the number of protocols, or an error code.

     *Since:* 3.0

gnutls_priority_set
-------------------

 -- Function: int gnutls_priority_set (gnutls_session_t SESSION,
          gnutls_priority_t PRIORITY)
     SESSION: is a 'gnutls_session_t' structure.

     PRIORITY: is a 'gnutls_priority_t' structure.

     Sets the priorities to use on the ciphers, key exchange methods,
     macs and compression methods.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_priority_set_direct
--------------------------

 -- Function: int gnutls_priority_set_direct (gnutls_session_t SESSION,
          const char * PRIORITIES, const char ** ERR_POS)
     SESSION: is a 'gnutls_session_t' structure.

     PRIORITIES: is a string describing priorities

     ERR_POS: In case of an error this will have the position in the
     string the error occured

     Sets the priorities to use on the ciphers, key exchange methods,
     macs and compression methods.  This function avoids keeping a
     priority cache and is used to directly set string priorities to a
     TLS session.  For documentation check the 'gnutls_priority_init()'
     .

     To simply use a reasonable default, consider using
     'gnutls_set_default_priority()' .

     *Returns:* On syntax error 'GNUTLS_E_INVALID_REQUEST' is returned,
     'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_priority_sign_list
-------------------------

 -- Function: int gnutls_priority_sign_list (gnutls_priority_t PCACHE,
          const unsigned int ** LIST)
     PCACHE: is a 'gnutls_prioritity_t' structure.

     LIST: will point to an integer list

     Get a list of available signature algorithms in the priority
     structure.

     *Returns:* the number of algorithms, or an error code.

     *Since:* 3.0

gnutls_protocol_get_id
----------------------

 -- Function: gnutls_protocol_t gnutls_protocol_get_id (const char *
          NAME)
     NAME: is a protocol name

     The names are compared in a case insensitive way.

     *Returns:* an id of the specified protocol, or
     'GNUTLS_VERSION_UNKNOWN' on error.

gnutls_protocol_get_name
------------------------

 -- Function: const char * gnutls_protocol_get_name (gnutls_protocol_t
          VERSION)
     VERSION: is a (gnutls) version number

     Convert a 'gnutls_protocol_t' value to a string.

     *Returns:* a string that contains the name of the specified TLS
     version (e.g., "TLS1.0"), or 'NULL' .

gnutls_protocol_get_version
---------------------------

 -- Function: gnutls_protocol_t gnutls_protocol_get_version
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get TLS version, a 'gnutls_protocol_t' value.

     *Returns:* The version of the currently used protocol.

gnutls_protocol_list
--------------------

 -- Function: const gnutls_protocol_t * gnutls_protocol_list ( VOID)

     Get a list of supported protocols, e.g.  SSL 3.0, TLS 1.0 etc.

     This function is not thread safe.

     *Returns:* a (0)-terminated list of 'gnutls_protocol_t' integers
     indicating the available protocols.

gnutls_psk_allocate_client_credentials
--------------------------------------

 -- Function: int gnutls_psk_allocate_client_credentials
          (gnutls_psk_client_credentials_t * SC)
     SC: is a pointer to a 'gnutls_psk_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to allocate it.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_psk_allocate_server_credentials
--------------------------------------

 -- Function: int gnutls_psk_allocate_server_credentials
          (gnutls_psk_server_credentials_t * SC)
     SC: is a pointer to a 'gnutls_psk_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to allocate it.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_psk_client_get_hint
--------------------------

 -- Function: const char * gnutls_psk_client_get_hint (gnutls_session_t
          SESSION)
     SESSION: is a gnutls session

     The PSK identity hint may give the client help in deciding which
     username to use.  This should only be called in case of PSK
     authentication and in case of a client.

     *Returns:* the identity hint of the peer, or 'NULL' in case of an
     error.

     *Since:* 2.4.0

gnutls_psk_free_client_credentials
----------------------------------

 -- Function: void gnutls_psk_free_client_credentials
          (gnutls_psk_client_credentials_t SC)
     SC: is a 'gnutls_psk_client_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to free (deallocate) it.

gnutls_psk_free_server_credentials
----------------------------------

 -- Function: void gnutls_psk_free_server_credentials
          (gnutls_psk_server_credentials_t SC)
     SC: is a 'gnutls_psk_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to free (deallocate) it.

gnutls_psk_server_get_username
------------------------------

 -- Function: const char * gnutls_psk_server_get_username
          (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     This should only be called in case of PSK authentication and in
     case of a server.

     *Returns:* the username of the peer, or 'NULL' in case of an error.

gnutls_psk_set_client_credentials
---------------------------------

 -- Function: int gnutls_psk_set_client_credentials
          (gnutls_psk_client_credentials_t RES, const char * USERNAME,
          const gnutls_datum_t * KEY, gnutls_psk_key_flags FLAGS)
     RES: is a 'gnutls_psk_client_credentials_t' structure.

     USERNAME: is the user's zero-terminated userid

     KEY: is the user's key

     FLAGS: indicate the format of the key, either 'GNUTLS_PSK_KEY_RAW'
     or 'GNUTLS_PSK_KEY_HEX' .

     This function sets the username and password, in a
     gnutls_psk_client_credentials_t structure.  Those will be used in
     PSK authentication.  'username' should be an ASCII string or UTF-8
     strings prepared using the "SASLprep" profile of "stringprep".  The
     key can be either in raw byte format or in Hex format (without the
     0x prefix).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_psk_set_client_credentials_function
------------------------------------------

 -- Function: void gnutls_psk_set_client_credentials_function
          (gnutls_psk_client_credentials_t CRED,
          gnutls_psk_client_credentials_function * FUNC)
     CRED: is a 'gnutls_psk_server_credentials_t' structure.

     FUNC: is the callback function

     This function can be used to set a callback to retrieve the
     username and password for client PSK authentication.  The
     callback's function form is: int (*callback)(gnutls_session_t,
     char** username, gnutls_datum_t* key);

     The 'username' and 'key' ->data must be allocated using
     'gnutls_malloc()' .  'username' should be ASCII strings or UTF-8
     strings prepared using the "SASLprep" profile of "stringprep".

     The callback function will be called once per handshake.

     The callback function should return 0 on success.  -1 indicates an
     error.

gnutls_psk_set_params_function
------------------------------

 -- Function: void gnutls_psk_set_params_function
          (gnutls_psk_server_credentials_t RES, gnutls_params_function *
          FUNC)
     RES: is a gnutls_psk_server_credentials_t structure

     FUNC: is the function to be called

     This function will set a callback in order for the server to get
     the Diffie-Hellman or RSA parameters for PSK authentication.  The
     callback should return 'GNUTLS_E_SUCCESS' (0) on success.

gnutls_psk_set_server_credentials_file
--------------------------------------

 -- Function: int gnutls_psk_set_server_credentials_file
          (gnutls_psk_server_credentials_t RES, const char *
          PASSWORD_FILE)
     RES: is a 'gnutls_psk_server_credentials_t' structure.

     PASSWORD_FILE: is the PSK password file (passwd.psk)

     This function sets the password file, in a
     'gnutls_psk_server_credentials_t' structure.  This password file
     holds usernames and keys and will be used for PSK authentication.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_psk_set_server_credentials_function
------------------------------------------

 -- Function: void gnutls_psk_set_server_credentials_function
          (gnutls_psk_server_credentials_t CRED,
          gnutls_psk_server_credentials_function * FUNC)
     CRED: is a 'gnutls_psk_server_credentials_t' structure.

     FUNC: is the callback function

     This function can be used to set a callback to retrieve the user's
     PSK credentials.  The callback's function form is: int
     (*callback)(gnutls_session_t, const char* username, gnutls_datum_t*
     key);

     'username' contains the actual username.  The 'key' must be filled
     in using the 'gnutls_malloc()' .

     In case the callback returned a negative number then gnutls will
     assume that the username does not exist.

     The callback function will only be called once per handshake.  The
     callback function should return 0 on success, while -1 indicates an
     error.

gnutls_psk_set_server_credentials_hint
--------------------------------------

 -- Function: int gnutls_psk_set_server_credentials_hint
          (gnutls_psk_server_credentials_t RES, const char * HINT)
     RES: is a 'gnutls_psk_server_credentials_t' structure.

     HINT: is the PSK identity hint string

     This function sets the identity hint, in a
     'gnutls_psk_server_credentials_t' structure.  This hint is sent to
     the client to help it chose a good PSK credential (i.e., username
     and password).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

     *Since:* 2.4.0

gnutls_psk_set_server_dh_params
-------------------------------

 -- Function: void gnutls_psk_set_server_dh_params
          (gnutls_psk_server_credentials_t RES, gnutls_dh_params_t
          DH_PARAMS)
     RES: is a gnutls_psk_server_credentials_t structure

     DH_PARAMS: is a structure that holds Diffie-Hellman parameters.

     This function will set the Diffie-Hellman parameters for an
     anonymous server to use.  These parameters will be used in
     Diffie-Hellman exchange with PSK cipher suites.

gnutls_psk_set_server_params_function
-------------------------------------

 -- Function: void gnutls_psk_set_server_params_function
          (gnutls_psk_server_credentials_t RES, gnutls_params_function *
          FUNC)
     RES: is a 'gnutls_certificate_credentials_t' structure

     FUNC: is the function to be called

     This function will set a callback in order for the server to get
     the Diffie-Hellman parameters for PSK authentication.  The callback
     should return 'GNUTLS_E_SUCCESS' (0) on success.

gnutls_random_art
-----------------

 -- Function: int gnutls_random_art (gnutls_random_art_t TYPE, const
          char * KEY_TYPE, unsigned int KEY_SIZE, void * FPR, size_t
          FPR_SIZE, gnutls_datum_t * ART)
     TYPE: The type of the random art (for now only
     'GNUTLS_RANDOM_ART_OPENSSH' is supported)

     KEY_TYPE: The type of the key (RSA, DSA etc.)

     KEY_SIZE: The size of the key in bits

     FPR: The fingerprint of the key

     FPR_SIZE: The size of the fingerprint

     ART: The returned random art

     This function will convert a given fingerprint to an "artistic"
     image.  The returned image is allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_range_split
------------------

 -- Function: int gnutls_range_split (gnutls_session_t SESSION, const
          gnutls_range_st * ORIG, gnutls_range_st * NEXT,
          gnutls_range_st * REMAINDER)
     SESSION: is a 'gnutls_session_t' structure

     ORIG: is the original range provided by the user

     NEXT: is the returned range that can be conveyed in a TLS record

     REMAINDER: is the returned remaining range

     This function should be used when it is required to hide the length
     of very long data that cannot be directly provided to
     'gnutls_record_send_range()' .  In that case this function should
     be called with the desired length hiding range in 'orig' .  The
     returned 'next' value should then be used in the next call to
     'gnutls_record_send_range()' with the partial data.  That process
     should be repeated until 'remainder' is (0,0).

     *Returns:* 0 in case splitting succeeds, non zero in case of error.
     Note that 'orig' is not changed, while the values of 'next' and
     'remainder' are modified to store the resulting values.

gnutls_record_can_use_length_hiding
-----------------------------------

 -- Function: int gnutls_record_can_use_length_hiding (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     If the session supports length-hiding padding, you can invoke
     'gnutls_range_send_message()' to send a message whose length is
     hidden in the given range.  If the session does not support length
     hiding padding, you can use the standard 'gnutls_record_send()'
     function, or 'gnutls_range_send_message()' making sure that the
     range is the same as the length of the message you are trying to
     send.

     *Returns:* true (1) if the current session supports length-hiding
     padding, false (0) if the current session does not.

gnutls_record_check_corked
--------------------------

 -- Function: size_t gnutls_record_check_corked (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function checks if there pending corked data in the gnutls
     buffers -see 'gnutls_record_cork()' .

     *Returns:* Returns the size of the corked data or zero.

     *Since:* 3.2.8

gnutls_record_check_pending
---------------------------

 -- Function: size_t gnutls_record_check_pending (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function checks if there are unread data in the gnutls
     buffers.  If the return value is non-zero the next call to
     'gnutls_record_recv()' is guaranteed not to block.

     *Returns:* Returns the size of the data or zero.

gnutls_record_cork
------------------

 -- Function: void gnutls_record_cork (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     If called, 'gnutls_record_send()' will no longer send any records.
     Any sent records will be cached until 'gnutls_record_uncork()' is
     called.

     This function is safe to use with DTLS after GnuTLS 3.3.0.

     *Since:* 3.1.9

gnutls_record_disable_padding
-----------------------------

 -- Function: void gnutls_record_disable_padding (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Used to disabled padding in TLS 1.0 and above.  Normally you do not
     need to use this function, but there are buggy clients that
     complain if a server pads the encrypted data.  This of course will
     disable protection against statistical attacks on the data.

     This functions is defunt since 3.1.7.  Random padding is disabled
     by default unless requested using 'gnutls_range_send_message()' .

gnutls_record_get_direction
---------------------------

 -- Function: int gnutls_record_get_direction (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function provides information about the internals of the
     record protocol and is only useful if a prior gnutls function call
     (e.g.  'gnutls_handshake()' ) was interrupted for some reason, that
     is, if a function returned 'GNUTLS_E_INTERRUPTED' or
     'GNUTLS_E_AGAIN' .  In such a case, you might want to call
     'select()' or 'poll()' before calling the interrupted gnutls
     function again.  To tell you whether a file descriptor should be
     selected for either reading or writing,
     'gnutls_record_get_direction()' returns 0 if the interrupted
     function was trying to read data, and 1 if it was trying to write
     data.

     This function's output is unreliable if you are using the 'session'
     in different threads, for sending and receiving.

     *Returns:* 0 if trying to read data, 1 if trying to write data.

gnutls_record_get_max_size
--------------------------

 -- Function: size_t gnutls_record_get_max_size (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get the record size.  The maximum record size is negotiated by the
     client after the first handshake message.

     *Returns:* The maximum record packet size in this connection.

gnutls_record_overhead_size
---------------------------

 -- Function: size_t gnutls_record_overhead_size (gnutls_session_t
          SESSION)
     SESSION: is 'gnutls_session_t'

     This function will return the set size in bytes of the overhead due
     to TLS (or DTLS) per record.

     *Since:* 3.2.2

gnutls_record_recv
------------------

 -- Function: ssize_t gnutls_record_recv (gnutls_session_t SESSION, void
          * DATA, size_t DATA_SIZE)
     SESSION: is a 'gnutls_session_t' structure.

     DATA: the buffer that the data will be read into

     DATA_SIZE: the number of requested bytes

     This function has the similar semantics with 'recv()' .  The only
     difference is that it accepts a GnuTLS session, and uses different
     error codes.  In the special case that a server requests a
     renegotiation, the client may receive an error code of
     'GNUTLS_E_REHANDSHAKE' .  This message may be simply ignored,
     replied with an alert 'GNUTLS_A_NO_RENEGOTIATION' , or replied with
     a new handshake, depending on the client's will.  If 'EINTR' is
     returned by the internal push function (the default is 'recv()' )
     then 'GNUTLS_E_INTERRUPTED' will be returned.  If
     'GNUTLS_E_INTERRUPTED' or 'GNUTLS_E_AGAIN' is returned, you must
     call this function again to get the data.  See also
     'gnutls_record_get_direction()' .  A server may also receive
     'GNUTLS_E_REHANDSHAKE' when a client has initiated a handshake.  In
     that case the server can only initiate a handshake or terminate the
     connection.

     *Returns:* The number of bytes received and zero on EOF (for stream
     connections).  A negative error code is returned in case of an
     error.  The number of bytes received might be less than the
     requested 'data_size' .

gnutls_record_recv_packet
-------------------------

 -- Function: ssize_t gnutls_record_recv_packet (gnutls_session_t
          SESSION, gnutls_packet_t * PACKET)
     SESSION: is a 'gnutls_session_t' structure.

     PACKET: the structure that will hold the packet data

     This is a lower-level function thatn 'gnutls_record_recv()' and
     allows to directly receive the whole decrypted packet.  That avoids
     a memory copy, and is mostly applicable to applications seeking
     high performance.

     The received packet is accessed using 'gnutls_packet_get()' and
     must be deinitialized using 'gnutls_packet_deinit()' .  The
     returned packet will be 'NULL' if the return value is zero (EOF).

     *Returns:* The number of bytes received and zero on EOF (for stream
     connections).  A negative error code is returned in case of an
     error.

     *Since:* 3.3.5

gnutls_record_recv_seq
----------------------

 -- Function: ssize_t gnutls_record_recv_seq (gnutls_session_t SESSION,
          void * DATA, size_t DATA_SIZE, unsigned char * SEQ)
     SESSION: is a 'gnutls_session_t' structure.

     DATA: the buffer that the data will be read into

     DATA_SIZE: the number of requested bytes

     SEQ: is the packet's 64-bit sequence number.  Should have space for
     8 bytes.

     This function is the same as 'gnutls_record_recv()' , except that
     it returns in addition to data, the sequence number of the data.
     This is useful in DTLS where record packets might be received
     out-of-order.  The returned 8-byte sequence number is an integer in
     big-endian format and should be treated as a unique message
     identification.

     *Returns:* The number of bytes received and zero on EOF. A negative
     error code is returned in case of an error.  The number of bytes
     received might be less than 'data_size' .

     *Since:* 3.0

gnutls_record_send
------------------

 -- Function: ssize_t gnutls_record_send (gnutls_session_t SESSION,
          const void * DATA, size_t DATA_SIZE)
     SESSION: is a 'gnutls_session_t' structure.

     DATA: contains the data to send

     DATA_SIZE: is the length of the data

     This function has the similar semantics with 'send()' .  The only
     difference is that it accepts a GnuTLS session, and uses different
     error codes.  Note that if the send buffer is full, 'send()' will
     block this function.  See the 'send()' documentation for more
     information.

     You can replace the default push function which is 'send()' , by
     using 'gnutls_transport_set_push_function()' .

     If the EINTR is returned by the internal push function then
     'GNUTLS_E_INTERRUPTED' will be returned.  If 'GNUTLS_E_INTERRUPTED'
     or 'GNUTLS_E_AGAIN' is returned, you must call this function again,
     with the exact same parameters; alternatively you could provide a
     'NULL' pointer for data, and 0 for size.  cf.
     'gnutls_record_get_direction()' .

     Note that in DTLS this function will return the
     'GNUTLS_E_LARGE_PACKET' error code if the send data exceed the data
     MTU value - as returned by 'gnutls_dtls_get_data_mtu()' .  The
     errno value EMSGSIZE also maps to 'GNUTLS_E_LARGE_PACKET' .  Note
     that since 3.2.13 this function can be called under cork in DTLS
     mode, and will refuse to send data over the MTU size by returning
     'GNUTLS_E_LARGE_PACKET' .

     *Returns:* The number of bytes sent, or a negative error code.  The
     number of bytes sent might be less than 'data_size' .  The maximum
     number of bytes this function can send in a single call depends on
     the negotiated maximum record size.

gnutls_record_send_range
------------------------

 -- Function: ssize_t gnutls_record_send_range (gnutls_session_t
          SESSION, const void * DATA, size_t DATA_SIZE, const
          gnutls_range_st * RANGE)
     SESSION: is a 'gnutls_session_t' structure.

     DATA: contains the data to send.

     DATA_SIZE: is the length of the data.

     RANGE: is the range of lengths in which the real data length must
     be hidden.

     This function operates like 'gnutls_record_send()' but, while
     'gnutls_record_send()' adds minimal padding to each TLS record,
     this function uses the TLS extra-padding feature to conceal the
     real data size within the range of lengths provided.  Some TLS
     sessions do not support extra padding (e.g.  stream ciphers in
     standard TLS or SSL3 sessions).  To know whether the current
     session supports extra padding, and hence length hiding, use the
     'gnutls_record_can_use_length_hiding()' function.

     *Note:* This function currently is only limited to blocking
     sockets.

     *Returns:* The number of bytes sent (that is data_size in a
     successful invocation), or a negative error code.

gnutls_record_set_max_empty_records
-----------------------------------

 -- Function: void gnutls_record_set_max_empty_records (gnutls_session_t
          SESSION, const unsigned int I)
     SESSION: is a 'gnutls_session_t' structure.

     I: is the desired value of maximum empty records that can be
     accepted in a row.

     Used to set the maximum number of empty fragments that can be
     accepted in a row.  Accepting many empty fragments is useful for
     receiving length-hidden content, where empty fragments filled with
     pad are sent to hide the real length of a message.  However, a
     malicious peer could send empty fragments to mount a DoS attack, so
     as a safety measure, a maximum number of empty fragments is
     accepted by default.  If you know your application must accept a
     given number of empty fragments in a row, you can use this function
     to set the desired value.

gnutls_record_set_max_size
--------------------------

 -- Function: ssize_t gnutls_record_set_max_size (gnutls_session_t
          SESSION, size_t SIZE)
     SESSION: is a 'gnutls_session_t' structure.

     SIZE: is the new size

     This function sets the maximum record packet size in this
     connection.  This property can only be set to clients.  The server
     may choose not to accept the requested size.

     Acceptable values are 512(=2^9), 1024(=2^10), 2048(=2^11) and
     4096(=2^12).  The requested record size does get in effect
     immediately only while sending data.  The receive part will take
     effect after a successful handshake.

     This function uses a TLS extension called 'max record size'.  Not
     all TLS implementations use or even understand this extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_record_set_timeout
-------------------------

 -- Function: void gnutls_record_set_timeout (gnutls_session_t SESSION,
          unsigned int MS)
     SESSION: is a 'gnutls_session_t' structure.

     MS: is a timeout value in milliseconds

     This function sets the receive timeout for the record layer to the
     provided value.  Use an 'ms' value of zero to disable timeout (the
     default).

     *Since:* 3.1.7

gnutls_record_uncork
--------------------

 -- Function: int gnutls_record_uncork (gnutls_session_t SESSION,
          unsigned int FLAGS)
     SESSION: is a 'gnutls_session_t' structure.

     FLAGS: Could be zero or 'GNUTLS_RECORD_WAIT'

     This resets the effect of 'gnutls_record_cork()' , and flushes any
     pending data.  If the 'GNUTLS_RECORD_WAIT' flag is specified then
     this function will block until the data is sent or a fatal error
     occurs (i.e., the function will retry on 'GNUTLS_E_AGAIN' and
     'GNUTLS_E_INTERRUPTED' ).

     If the flag 'GNUTLS_RECORD_WAIT' is not specified and the function
     is interrupted then the 'GNUTLS_E_AGAIN' or 'GNUTLS_E_INTERRUPTED'
     errors will be returned.  To obtain the data left in the corked
     buffer use 'gnutls_record_check_corked()' .

     *Returns:* On success the number of transmitted data is returned,
     or otherwise a negative error code.

     *Since:* 3.1.9

gnutls_rehandshake
------------------

 -- Function: int gnutls_rehandshake (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function will renegotiate security parameters with the client.
     This should only be called in case of a server.

     This message informs the peer that we want to renegotiate
     parameters (perform a handshake).

     If this function succeeds (returns 0), you must call the
     'gnutls_handshake()' function in order to negotiate the new
     parameters.

     Since TLS is full duplex some application data might have been sent
     during peer's processing of this message.  In that case one should
     call 'gnutls_record_recv()' until GNUTLS_E_REHANDSHAKE is returned
     to clear any pending data.  Care must be taken if rehandshake is
     mandatory to terminate if it does not start after some threshold.

     If the client does not wish to renegotiate parameters he should
     reply with an alert message, thus the return code will be
     'GNUTLS_E_WARNING_ALERT_RECEIVED' and the alert will be
     'GNUTLS_A_NO_RENEGOTIATION' .  A client may also choose to ignore
     this message.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

gnutls_safe_renegotiation_status
--------------------------------

 -- Function: int gnutls_safe_renegotiation_status (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Can be used to check whether safe renegotiation is being used in
     the current session.

     *Returns:* 0 when safe renegotiation is not used and non (0) when
     safe renegotiation is used.

     *Since:* 2.10.0

gnutls_sec_param_get_name
-------------------------

 -- Function: const char * gnutls_sec_param_get_name (gnutls_sec_param_t
          PARAM)
     PARAM: is a security parameter

     Convert a 'gnutls_sec_param_t' value to a string.

     *Returns:* a pointer to a string that contains the name of the
     specified security level, or 'NULL' .

     *Since:* 2.12.0

gnutls_sec_param_to_pk_bits
---------------------------

 -- Function: unsigned int gnutls_sec_param_to_pk_bits
          (gnutls_pk_algorithm_t ALGO, gnutls_sec_param_t PARAM)
     ALGO: is a public key algorithm

     PARAM: is a security parameter

     When generating private and public key pairs a difficult question
     is which size of "bits" the modulus will be in RSA and the group
     size in DSA. The easy answer is 1024, which is also wrong.  This
     function will convert a human understandable security parameter to
     an appropriate size for the specific algorithm.

     *Returns:* The number of bits, or (0).

     *Since:* 2.12.0

gnutls_sec_param_to_symmetric_bits
----------------------------------

 -- Function: unsigned int gnutls_sec_param_to_symmetric_bits
          (gnutls_sec_param_t PARAM)
     PARAM: is a security parameter

     This function will return the number of bits that correspond to
     symmetric cipher strength for the given security parameter.

     *Returns:* The number of bits, or (0).

     *Since:* 3.3.0

gnutls_server_name_get
----------------------

 -- Function: int gnutls_server_name_get (gnutls_session_t SESSION, void
          * DATA, size_t * DATA_LENGTH, unsigned int * TYPE, unsigned
          int INDX)
     SESSION: is a 'gnutls_session_t' structure.

     DATA: will hold the data

     DATA_LENGTH: will hold the data length.  Must hold the maximum size
     of data.

     TYPE: will hold the server name indicator type

     INDX: is the index of the server_name

     This function will allow you to get the name indication (if any), a
     client has sent.  The name indication may be any of the enumeration
     gnutls_server_name_type_t.

     If 'type' is GNUTLS_NAME_DNS, then this function is to be used by
     servers that support virtual hosting, and the data will be a null
     terminated UTF-8 string.

     If 'data' has not enough size to hold the server name
     GNUTLS_E_SHORT_MEMORY_BUFFER is returned, and 'data_length' will
     hold the required size.

     'index' is used to retrieve more than one server names (if sent by
     the client).  The first server name has an index of 0, the second 1
     and so on.  If no name with the given index exists
     GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_server_name_set
----------------------

 -- Function: int gnutls_server_name_set (gnutls_session_t SESSION,
          gnutls_server_name_type_t TYPE, const void * NAME, size_t
          NAME_LENGTH)
     SESSION: is a 'gnutls_session_t' structure.

     TYPE: specifies the indicator type

     NAME: is a string that contains the server name.

     NAME_LENGTH: holds the length of name

     This function is to be used by clients that want to inform (via a
     TLS extension mechanism) the server of the name they connected to.
     This should be used by clients that connect to servers that do
     virtual hosting.

     The value of 'name' depends on the 'type' type.  In case of
     'GNUTLS_NAME_DNS' , an ASCII (0)-terminated domain name string,
     without the trailing dot, is expected.  IPv4 or IPv6 addresses are
     not permitted.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_session_channel_binding
------------------------------

 -- Function: int gnutls_session_channel_binding (gnutls_session_t
          SESSION, gnutls_channel_binding_t CBTYPE, gnutls_datum_t * CB)
     SESSION: is a 'gnutls_session_t' structure.

     CBTYPE: an 'gnutls_channel_binding_t' enumeration type

     CB: output buffer array with data

     Extract given channel binding data of the 'cbtype' (e.g.,
     'GNUTLS_CB_TLS_UNIQUE' ) type.

     *Returns:* 'GNUTLS_E_SUCCESS' on success,
     'GNUTLS_E_UNIMPLEMENTED_FEATURE' if the 'cbtype' is unsupported,
     'GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE' if the data is not
     currently available, or an error code.

     *Since:* 2.12.0

gnutls_session_enable_compatibility_mode
----------------------------------------

 -- Function: void gnutls_session_enable_compatibility_mode
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function can be used to disable certain (security) features in
     TLS in order to maintain maximum compatibility with buggy clients.
     Because several trade-offs with security are enabled, if required
     they will be reported through the audit subsystem.

     Normally only servers that require maximum compatibility with
     everything out there, need to call this function.

     Note that this function must be called after any call to
     gnutls_priority functions.

gnutls_session_force_valid
--------------------------

 -- Function: void gnutls_session_force_valid (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Clears the invalid flag in a session.  That means that sessions
     were corrupt or invalid data were received can be re-used.  Use
     only when debugging or experimenting with the TLS protocol.  Should
     not be used in typical applications.

gnutls_session_get_data
-----------------------

 -- Function: int gnutls_session_get_data (gnutls_session_t SESSION,
          void * SESSION_DATA, size_t * SESSION_DATA_SIZE)
     SESSION: is a 'gnutls_session_t' structure.

     SESSION_DATA: is a pointer to space to hold the session.

     SESSION_DATA_SIZE: is the session_data's size, or it will be set by
     the function.

     Returns all session parameters needed to be stored to support
     resumption.  The client should call this, and store the returned
     session data.  A session may be resumed later by calling
     'gnutls_session_set_data()' .  This function must be called after a
     successful (full) handshake.  It should not be used in resumed
     sessions -see 'gnutls_session_is_resumed()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_session_get_data2
------------------------

 -- Function: int gnutls_session_get_data2 (gnutls_session_t SESSION,
          gnutls_datum_t * DATA)
     SESSION: is a 'gnutls_session_t' structure.

     DATA: is a pointer to a datum that will hold the session.

     Returns all session parameters needed to be stored to support
     resumption.  The client should call this, and store the returned
     session data.  A session may be resumed later by calling
     'gnutls_session_set_data()' .  This function must be called after a
     successful (full) handshake.  It should not be used in resumed
     sessions -see 'gnutls_session_is_resumed()' .

     The returned 'data' are allocated and must be released using
     'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_session_get_desc
-----------------------

 -- Function: char * gnutls_session_get_desc (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     This function returns a string describing the current session.  The
     string is null terminated and allocated using 'gnutls_malloc()' .

     *Returns:* a description of the protocols and algorithms in the
     current session.

     *Since:* 3.1.10

gnutls_session_get_id
---------------------

 -- Function: int gnutls_session_get_id (gnutls_session_t SESSION, void
          * SESSION_ID, size_t * SESSION_ID_SIZE)
     SESSION: is a 'gnutls_session_t' structure.

     SESSION_ID: is a pointer to space to hold the session id.

     SESSION_ID_SIZE: initially should contain the maximum 'session_id'
     size and will be updated.

     Returns the current session ID. This can be used if you want to
     check if the next session you tried to resume was actually resumed.
     That is because resumed sessions share the same session ID with the
     original session.

     The session ID is selected by the server, that identify the current
     session.  In TLS 1.0 and SSL 3.0 session id is always less than 32
     bytes.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_session_get_id2
----------------------

 -- Function: int gnutls_session_get_id2 (gnutls_session_t SESSION,
          gnutls_datum_t * SESSION_ID)
     SESSION: is a 'gnutls_session_t' structure.

     SESSION_ID: will point to the session ID.

     Returns the current session ID. The returned data should be treated
     as constant.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

     *Since:* 3.1.4

gnutls_session_get_ptr
----------------------

 -- Function: void * gnutls_session_get_ptr (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Get user pointer for session.  Useful in callbacks.  This is the
     pointer set with 'gnutls_session_set_ptr()' .

     *Returns:* the user given pointer from the session structure, or
     'NULL' if it was never set.

gnutls_session_get_random
-------------------------

 -- Function: void gnutls_session_get_random (gnutls_session_t SESSION,
          gnutls_datum_t * CLIENT, gnutls_datum_t * SERVER)
     SESSION: is a 'gnutls_session_t' structure.

     CLIENT: the client part of the random

     SERVER: the server part of the random

     This function returns pointers to the client and server random
     fields used in the TLS handshake.  The pointers are not to be
     modified or deallocated.

     If a client random value has not yet been established, the output
     will be garbage.

     *Since:* 3.0

gnutls_session_is_resumed
-------------------------

 -- Function: int gnutls_session_is_resumed (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Check whether session is resumed or not.

     *Returns:* non zero if this session is resumed, or a zero if this
     is a new session.

gnutls_session_resumption_requested
-----------------------------------

 -- Function: int gnutls_session_resumption_requested (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Check whether the client has asked for session resumption.  This
     function is valid only on server side.

     *Returns:* non zero if session resumption was asked, or a zero if
     not.

gnutls_session_set_data
-----------------------

 -- Function: int gnutls_session_set_data (gnutls_session_t SESSION,
          const void * SESSION_DATA, size_t SESSION_DATA_SIZE)
     SESSION: is a 'gnutls_session_t' structure.

     SESSION_DATA: is a pointer to space to hold the session.

     SESSION_DATA_SIZE: is the session's size

     Sets all session parameters, in order to resume a previously
     established session.  The session data given must be the one
     returned by 'gnutls_session_get_data()' .  This function should be
     called before 'gnutls_handshake()' .

     Keep in mind that session resuming is advisory.  The server may
     choose not to resume the session, thus a full handshake will be
     performed.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_session_set_id
---------------------

 -- Function: int gnutls_session_set_id (gnutls_session_t SESSION, const
          gnutls_datum_t * SID)
     SESSION: is a 'gnutls_session_t' structure.

     SID: the session identifier

     This function sets the session ID to be used in a client hello.
     This is a function intended for exceptional uses.  Do not use this
     function unless you are implementing a custom protocol.

     To set session resumption parameters use
     'gnutls_session_set_data()' instead.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_session_set_premaster
----------------------------

 -- Function: int gnutls_session_set_premaster (gnutls_session_t
          SESSION, unsigned int ENTITY, gnutls_protocol_t VERSION,
          gnutls_kx_algorithm_t KX, gnutls_cipher_algorithm_t CIPHER,
          gnutls_mac_algorithm_t MAC, gnutls_compression_method_t COMP,
          const gnutls_datum_t * MASTER, const gnutls_datum_t *
          SESSION_ID)
     SESSION: is a 'gnutls_session_t' structure.

     ENTITY: GNUTLS_SERVER or GNUTLS_CLIENT

     VERSION: the TLS protocol version

     KX: the key exchange method

     CIPHER: the cipher

     MAC: the MAC algorithm

     COMP: the compression method

     MASTER: the master key to use

     SESSION_ID: the session identifier

     This function sets the premaster secret in a session.  This is a
     function intended for exceptional uses.  Do not use this function
     unless you are implementing a legacy protocol.  Use
     'gnutls_session_set_data()' instead.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

gnutls_session_set_ptr
----------------------

 -- Function: void gnutls_session_set_ptr (gnutls_session_t SESSION,
          void * PTR)
     SESSION: is a 'gnutls_session_t' structure.

     PTR: is the user pointer

     This function will set (associate) the user given pointer 'ptr' to
     the session structure.  This pointer can be accessed with
     'gnutls_session_get_ptr()' .

gnutls_session_ticket_enable_client
-----------------------------------

 -- Function: int gnutls_session_ticket_enable_client (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Request that the client should attempt session resumption using
     SessionTicket.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

     *Since:* 2.10.0

gnutls_session_ticket_enable_server
-----------------------------------

 -- Function: int gnutls_session_ticket_enable_server (gnutls_session_t
          SESSION, const gnutls_datum_t * KEY)
     SESSION: is a 'gnutls_session_t' structure.

     KEY: key to encrypt session parameters.

     Request that the server should attempt session resumption using
     SessionTicket.  'key' must be initialized with
     'gnutls_session_ticket_key_generate()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

     *Since:* 2.10.0

gnutls_session_ticket_key_generate
----------------------------------

 -- Function: int gnutls_session_ticket_key_generate (gnutls_datum_t *
          KEY)
     KEY: is a pointer to a 'gnutls_datum_t' which will contain a newly
     created key.

     Generate a random key to encrypt security parameters within
     SessionTicket.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

     *Since:* 2.10.0

gnutls_set_default_priority
---------------------------

 -- Function: int gnutls_set_default_priority (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Sets the default priority on the ciphers, key exchange methods,
     macs and compression methods.  For more fine-tuning you could use
     'gnutls_priority_set_direct()' or 'gnutls_priority_set()' instead.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, or an error code.

gnutls_sign_algorithm_get
-------------------------

 -- Function: int gnutls_sign_algorithm_get (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Returns the signature algorithm that is (or will be) used in this
     session by the server to sign data.

     *Returns:* The sign algorithm or 'GNUTLS_SIGN_UNKNOWN' .

     *Since:* 3.1.1

gnutls_sign_algorithm_get_client
--------------------------------

 -- Function: int gnutls_sign_algorithm_get_client (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Returns the signature algorithm that is (or will be) used in this
     session by the client to sign data.

     *Returns:* The sign algorithm or 'GNUTLS_SIGN_UNKNOWN' .

     *Since:* 3.1.11

gnutls_sign_algorithm_get_requested
-----------------------------------

 -- Function: int gnutls_sign_algorithm_get_requested (gnutls_session_t
          SESSION, size_t INDX, gnutls_sign_algorithm_t * ALGO)
     SESSION: is a 'gnutls_session_t' structure.

     INDX: is an index of the signature algorithm to return

     ALGO: the returned certificate type will be stored there

     Returns the signature algorithm specified by index that was
     requested by the peer.  If the specified index has no data
     available this function returns
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' .  If the negotiated TLS
     version does not support signature algorithms then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned even for
     the first index.  The first index is 0.

     This function is useful in the certificate callback functions to
     assist in selecting the correct certificate.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise an error code is returned.

     *Since:* 2.10.0

gnutls_sign_get_hash_algorithm
------------------------------

 -- Function: gnutls_digest_algorithm_t gnutls_sign_get_hash_algorithm
          (gnutls_sign_algorithm_t SIGN)
     SIGN: is a signature algorithm

     This function returns the digest algorithm corresponding to the
     given signature algorithms.

     *Since:* 3.1.1

     *Returns:* return a 'gnutls_digest_algorithm_t' value, or
     'GNUTLS_DIG_UNKNOWN' on error.

gnutls_sign_get_id
------------------

 -- Function: gnutls_sign_algorithm_t gnutls_sign_get_id (const char *
          NAME)
     NAME: is a sign algorithm name

     The names are compared in a case insensitive way.

     *Returns:* return a 'gnutls_sign_algorithm_t' value corresponding
     to the specified algorithm, or 'GNUTLS_SIGN_UNKNOWN' on error.

gnutls_sign_get_name
--------------------

 -- Function: const char * gnutls_sign_get_name (gnutls_sign_algorithm_t
          ALGORITHM)
     ALGORITHM: is a sign algorithm

     Convert a 'gnutls_sign_algorithm_t' value to a string.

     *Returns:* a string that contains the name of the specified sign
     algorithm, or 'NULL' .

gnutls_sign_get_pk_algorithm
----------------------------

 -- Function: gnutls_pk_algorithm_t gnutls_sign_get_pk_algorithm
          (gnutls_sign_algorithm_t SIGN)
     SIGN: is a signature algorithm

     This function returns the public key algorithm corresponding to the
     given signature algorithms.

     *Since:* 3.1.1

     *Returns:* return a 'gnutls_pk_algorithm_t' value, or
     'GNUTLS_PK_UNKNOWN' on error.

gnutls_sign_is_secure
---------------------

 -- Function: int gnutls_sign_is_secure (gnutls_sign_algorithm_t
          ALGORITHM)
     ALGORITHM: is a sign algorithm

     *Returns:* Non-zero if the provided signature algorithm is
     considered to be secure.

gnutls_sign_list
----------------

 -- Function: const gnutls_sign_algorithm_t * gnutls_sign_list ( VOID)

     Get a list of supported public key signature algorithms.

     *Returns:* a (0)-terminated list of 'gnutls_sign_algorithm_t'
     integers indicating the available ciphers.

gnutls_srp_allocate_client_credentials
--------------------------------------

 -- Function: int gnutls_srp_allocate_client_credentials
          (gnutls_srp_client_credentials_t * SC)
     SC: is a pointer to a 'gnutls_srp_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to allocate it.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

gnutls_srp_allocate_server_credentials
--------------------------------------

 -- Function: int gnutls_srp_allocate_server_credentials
          (gnutls_srp_server_credentials_t * SC)
     SC: is a pointer to a 'gnutls_srp_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to allocate it.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

gnutls_srp_base64_decode
------------------------

 -- Function: int gnutls_srp_base64_decode (const gnutls_datum_t *
          B64_DATA, char * RESULT, size_t * RESULT_SIZE)
     B64_DATA: contain the encoded data

     RESULT: the place where decoded data will be copied

     RESULT_SIZE: holds the size of the result

     This function will decode the given encoded data, using the base64
     encoding found in libsrp.

     Note that 'b64_data' should be null terminated.

     Warning!  This base64 encoding is not the "standard" encoding, so
     do not use it for non-SRP purposes.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the buffer given is
     not long enough, or 0 on success.

gnutls_srp_base64_decode_alloc
------------------------------

 -- Function: int gnutls_srp_base64_decode_alloc (const gnutls_datum_t *
          B64_DATA, gnutls_datum_t * RESULT)
     B64_DATA: contains the encoded data

     RESULT: the place where decoded data lie

     This function will decode the given encoded data.  The decoded data
     will be allocated, and stored into result.  It will decode using
     the base64 algorithm as used in libsrp.

     You should use 'gnutls_free()' to free the returned data.

     Warning!  This base64 encoding is not the "standard" encoding, so
     do not use it for non-SRP purposes.

     *Returns:* 0 on success, or an error code.

gnutls_srp_base64_encode
------------------------

 -- Function: int gnutls_srp_base64_encode (const gnutls_datum_t * DATA,
          char * RESULT, size_t * RESULT_SIZE)
     DATA: contain the raw data

     RESULT: the place where base64 data will be copied

     RESULT_SIZE: holds the size of the result

     This function will convert the given data to printable data, using
     the base64 encoding, as used in the libsrp.  This is the encoding
     used in SRP password files.  If the provided buffer is not long
     enough GNUTLS_E_SHORT_MEMORY_BUFFER is returned.

     Warning!  This base64 encoding is not the "standard" encoding, so
     do not use it for non-SRP purposes.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the buffer given is
     not long enough, or 0 on success.

gnutls_srp_base64_encode_alloc
------------------------------

 -- Function: int gnutls_srp_base64_encode_alloc (const gnutls_datum_t *
          DATA, gnutls_datum_t * RESULT)
     DATA: contains the raw data

     RESULT: will hold the newly allocated encoded data

     This function will convert the given data to printable data, using
     the base64 encoding.  This is the encoding used in SRP password
     files.  This function will allocate the required memory to hold the
     encoded data.

     You should use 'gnutls_free()' to free the returned data.

     Warning!  This base64 encoding is not the "standard" encoding, so
     do not use it for non-SRP purposes.

     *Returns:* 0 on success, or an error code.

gnutls_srp_free_client_credentials
----------------------------------

 -- Function: void gnutls_srp_free_client_credentials
          (gnutls_srp_client_credentials_t SC)
     SC: is a 'gnutls_srp_client_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to free (deallocate) it.

gnutls_srp_free_server_credentials
----------------------------------

 -- Function: void gnutls_srp_free_server_credentials
          (gnutls_srp_server_credentials_t SC)
     SC: is a 'gnutls_srp_server_credentials_t' structure.

     This structure is complex enough to manipulate directly thus this
     helper function is provided in order to free (deallocate) it.

gnutls_srp_server_get_username
------------------------------

 -- Function: const char * gnutls_srp_server_get_username
          (gnutls_session_t SESSION)
     SESSION: is a gnutls session

     This function will return the username of the peer.  This should
     only be called in case of SRP authentication and in case of a
     server.  Returns NULL in case of an error.

     *Returns:* SRP username of the peer, or NULL in case of error.

gnutls_srp_set_client_credentials
---------------------------------

 -- Function: int gnutls_srp_set_client_credentials
          (gnutls_srp_client_credentials_t RES, const char * USERNAME,
          const char * PASSWORD)
     RES: is a 'gnutls_srp_client_credentials_t' structure.

     USERNAME: is the user's userid

     PASSWORD: is the user's password

     This function sets the username and password, in a
     'gnutls_srp_client_credentials_t' structure.  Those will be used in
     SRP authentication.  'username' and 'password' should be ASCII
     strings or UTF-8 strings prepared using the "SASLprep" profile of
     "stringprep".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

gnutls_srp_set_client_credentials_function
------------------------------------------

 -- Function: void gnutls_srp_set_client_credentials_function
          (gnutls_srp_client_credentials_t CRED,
          gnutls_srp_client_credentials_function * FUNC)
     CRED: is a 'gnutls_srp_server_credentials_t' structure.

     FUNC: is the callback function

     This function can be used to set a callback to retrieve the
     username and password for client SRP authentication.  The
     callback's function form is:

     int (*callback)(gnutls_session_t, char** username, char**password);

     The 'username' and 'password' must be allocated using
     'gnutls_malloc()' .  'username' and 'password' should be ASCII
     strings or UTF-8 strings prepared using the "SASLprep" profile of
     "stringprep".

     The callback function will be called once per handshake before the
     initial hello message is sent.

     The callback should not return a negative error code the second
     time called, since the handshake procedure will be aborted.

     The callback function should return 0 on success.  -1 indicates an
     error.

gnutls_srp_set_prime_bits
-------------------------

 -- Function: void gnutls_srp_set_prime_bits (gnutls_session_t SESSION,
          unsigned int BITS)
     SESSION: is a 'gnutls_session_t' structure.

     BITS: is the number of bits

     This function sets the minimum accepted number of bits, for use in
     an SRP key exchange.  If zero, the default 2048 bits will be used.

     In the client side it sets the minimum accepted number of bits.  If
     a server sends a prime with less bits than that
     'GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER' will be returned by the
     handshake.

     This function has no effect in server side.

     *Since:* 2.6.0

gnutls_srp_set_server_credentials_file
--------------------------------------

 -- Function: int gnutls_srp_set_server_credentials_file
          (gnutls_srp_server_credentials_t RES, const char *
          PASSWORD_FILE, const char * PASSWORD_CONF_FILE)
     RES: is a 'gnutls_srp_server_credentials_t' structure.

     PASSWORD_FILE: is the SRP password file (tpasswd)

     PASSWORD_CONF_FILE: is the SRP password conf file (tpasswd.conf)

     This function sets the password files, in a
     'gnutls_srp_server_credentials_t' structure.  Those password files
     hold usernames and verifiers and will be used for SRP
     authentication.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

gnutls_srp_set_server_credentials_function
------------------------------------------

 -- Function: void gnutls_srp_set_server_credentials_function
          (gnutls_srp_server_credentials_t CRED,
          gnutls_srp_server_credentials_function * FUNC)
     CRED: is a 'gnutls_srp_server_credentials_t' structure.

     FUNC: is the callback function

     This function can be used to set a callback to retrieve the user's
     SRP credentials.  The callback's function form is:

     int (*callback)(gnutls_session_t, const char* username,
     gnutls_datum_t *salt, gnutls_datum_t *verifier, gnutls_datum_t
     *generator, gnutls_datum_t *prime);

     'username' contains the actual username.  The 'salt' , 'verifier' ,
     'generator' and 'prime' must be filled in using the
     'gnutls_malloc()' .  For convenience 'prime' and 'generator' may
     also be one of the static parameters defined in gnutls.h.

     Initially, the data field is NULL in every 'gnutls_datum_t'
     structure that the callback has to fill in.  When the callback is
     done GnuTLS deallocates all of those buffers which are non-NULL,
     regardless of the return value.

     In order to prevent attackers from guessing valid usernames, if a
     user does not exist, g and n values should be filled in using a
     random user's parameters.  In that case the callback must return
     the special value (1).  See 'gnutls_srp_set_server_fake_salt_seed'
     too.  If this is not required for your application, return a
     negative number from the callback to abort the handshake.

     The callback function will only be called once per handshake.  The
     callback function should return 0 on success, while -1 indicates an
     error.

gnutls_srp_set_server_fake_salt_seed
------------------------------------

 -- Function: void gnutls_srp_set_server_fake_salt_seed
          (gnutls_srp_server_credentials_t CRED, const gnutls_datum_t *
          SEED, unsigned int SALT_LENGTH)
     CRED: is a 'gnutls_srp_server_credentials_t' structure

     SEED: is the seed data, only needs to be valid until the function
     returns; size of the seed must be greater than zero

     SALT_LENGTH: is the length of the generated fake salts

     This function sets the seed that is used to generate salts for
     invalid (non-existent) usernames.

     In order to prevent attackers from guessing valid usernames, when a
     user does not exist gnutls generates a salt and a verifier and
     proceeds with the protocol as usual.  The authentication will
     ultimately fail, but the client cannot tell whether the username is
     valid (exists) or invalid.

     If an attacker learns the seed, given a salt (which is part of the
     handshake) which was generated when the seed was in use, it can
     tell whether or not the authentication failed because of an unknown
     username.  This seed cannot be used to reveal application data or
     passwords.

     'salt_length' should represent the salt length your application
     uses.  Generating fake salts longer than 20 bytes is not supported.

     By default the seed is a random value, different each time a
     'gnutls_srp_server_credentials_t' is allocated and fake salts are
     16 bytes long.

     *Since:* 3.3.0

gnutls_srp_verifier
-------------------

 -- Function: int gnutls_srp_verifier (const char * USERNAME, const char
          * PASSWORD, const gnutls_datum_t * SALT, const gnutls_datum_t
          * GENERATOR, const gnutls_datum_t * PRIME, gnutls_datum_t *
          RES)
     USERNAME: is the user's name

     PASSWORD: is the user's password

     SALT: should be some randomly generated bytes

     GENERATOR: is the generator of the group

     PRIME: is the group's prime

     RES: where the verifier will be stored.

     This function will create an SRP verifier, as specified in RFC2945.
     The 'prime' and 'generator' should be one of the static parameters
     defined in gnutls/gnutls.h or may be generated.

     The verifier will be allocated with 'gnutls_malloc' () and will be
     stored in 'res' using binary format.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or an
     error code.

gnutls_srtp_get_keys
--------------------

 -- Function: int gnutls_srtp_get_keys (gnutls_session_t SESSION, void *
          KEY_MATERIAL, unsigned int KEY_MATERIAL_SIZE, gnutls_datum_t *
          CLIENT_KEY, gnutls_datum_t * CLIENT_SALT, gnutls_datum_t *
          SERVER_KEY, gnutls_datum_t * SERVER_SALT)
     SESSION: is a 'gnutls_session_t' structure.

     KEY_MATERIAL: Space to hold the generated key material

     KEY_MATERIAL_SIZE: The maximum size of the key material

     CLIENT_KEY: The master client write key, pointing inside the key
     material

     CLIENT_SALT: The master client write salt, pointing inside the key
     material

     SERVER_KEY: The master server write key, pointing inside the key
     material

     SERVER_SALT: The master server write salt, pointing inside the key
     material

     This is a helper function to generate the keying material for SRTP.
     It requires the space of the key material to be pre-allocated
     (should be at least 2x the maximum key size and salt size).  The
     'client_key' , 'client_salt' , 'server_key' and 'server_salt' are
     convenience datums that point inside the key material.  They may be
     'NULL' .

     *Returns:* On success the size of the key material is returned,
     otherwise, 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the buffer given is
     not sufficient, or a negative error code.

     Since 3.1.4

gnutls_srtp_get_mki
-------------------

 -- Function: int gnutls_srtp_get_mki (gnutls_session_t SESSION,
          gnutls_datum_t * MKI)
     SESSION: is a 'gnutls_session_t' structure.

     MKI: will hold the MKI

     This function exports the negotiated Master Key Identifier,
     received by the peer if any.  The returned value in 'mki' should be
     treated as constant and valid only during the session's lifetime.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     Since 3.1.4

gnutls_srtp_get_profile_id
--------------------------

 -- Function: int gnutls_srtp_get_profile_id (const char * NAME,
          gnutls_srtp_profile_t * PROFILE)
     NAME: The name of the profile to look up

     PROFILE: Will hold the profile id

     This function allows you to look up a profile based on a string.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     Since 3.1.4

gnutls_srtp_get_profile_name
----------------------------

 -- Function: const char * gnutls_srtp_get_profile_name
          (gnutls_srtp_profile_t PROFILE)
     PROFILE: The profile to look up a string for

     This function allows you to get the corresponding name for a SRTP
     protection profile.

     *Returns:* On success, the name of a SRTP profile as a string,
     otherwise NULL.

     Since 3.1.4

gnutls_srtp_get_selected_profile
--------------------------------

 -- Function: int gnutls_srtp_get_selected_profile (gnutls_session_t
          SESSION, gnutls_srtp_profile_t * PROFILE)
     SESSION: is a 'gnutls_session_t' structure.

     PROFILE: will hold the profile

     This function allows you to get the negotiated SRTP profile.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     Since 3.1.4

gnutls_srtp_set_mki
-------------------

 -- Function: int gnutls_srtp_set_mki (gnutls_session_t SESSION, const
          gnutls_datum_t * MKI)
     SESSION: is a 'gnutls_session_t' structure.

     MKI: holds the MKI

     This function sets the Master Key Identifier, to be used by this
     session (if any).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     Since 3.1.4

gnutls_srtp_set_profile
-----------------------

 -- Function: int gnutls_srtp_set_profile (gnutls_session_t SESSION,
          gnutls_srtp_profile_t PROFILE)
     SESSION: is a 'gnutls_session_t' structure.

     PROFILE: is the profile id to add.

     This function is to be used by both clients and servers, to declare
     what SRTP profiles they support, to negotiate with the peer.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

     Since 3.1.4

gnutls_srtp_set_profile_direct
------------------------------

 -- Function: int gnutls_srtp_set_profile_direct (gnutls_session_t
          SESSION, const char * PROFILES, const char ** ERR_POS)
     SESSION: is a 'gnutls_session_t' structure.

     PROFILES: is a string that contains the supported SRTP profiles,
     separated by colons.

     ERR_POS: In case of an error this will have the position in the
     string the error occured, may be NULL.

     This function is to be used by both clients and servers, to declare
     what SRTP profiles they support, to negotiate with the peer.

     *Returns:* On syntax error 'GNUTLS_E_INVALID_REQUEST' is returned,
     'GNUTLS_E_SUCCESS' on success, or an error code.

     Since 3.1.4

gnutls_store_commitment
-----------------------

 -- Function: int gnutls_store_commitment (const char * DB_NAME,
          gnutls_tdb_t TDB, const char * HOST, const char * SERVICE,
          gnutls_digest_algorithm_t HASH_ALGO, const gnutls_datum_t *
          HASH, time_t EXPIRATION, unsigned int FLAGS)
     DB_NAME: A file specifying the stored keys (use NULL for the
     default)

     TDB: A storage structure or NULL to use the default

     HOST: The peer's name

     SERVICE: non-NULL if this key is specific to a service (e.g.  http)

     HASH_ALGO: The hash algorithm type

     HASH: The raw hash

     EXPIRATION: The expiration time (use 0 to disable expiration)

     FLAGS: should be 0.

     This function will store the provided hash commitment to the list
     of stored public keys.  The key with the given hash will be
     considered valid until the provided expiration time.

     The 'store' variable if non-null specifies a custom backend for the
     storage of entries.  If it is NULL then the default file backend
     will be used.

     Note that this function is not thread safe with the default
     backend.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0

gnutls_store_pubkey
-------------------

 -- Function: int gnutls_store_pubkey (const char * DB_NAME,
          gnutls_tdb_t TDB, const char * HOST, const char * SERVICE,
          gnutls_certificate_type_t CERT_TYPE, const gnutls_datum_t *
          CERT, time_t EXPIRATION, unsigned int FLAGS)
     DB_NAME: A file specifying the stored keys (use NULL for the
     default)

     TDB: A storage structure or NULL to use the default

     HOST: The peer's name

     SERVICE: non-NULL if this key is specific to a service (e.g.  http)

     CERT_TYPE: The type of the certificate

     CERT: The data of the certificate

     EXPIRATION: The expiration time (use 0 to disable expiration)

     FLAGS: should be 0.

     This function will store the provided (raw or DER-encoded)
     certificate to the list of stored public keys.  The key will be
     considered valid until the provided expiration time.

     The 'store' variable if non-null specifies a custom backend for the
     storage of entries.  If it is NULL then the default file backend
     will be used.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0.13

gnutls_strerror
---------------

 -- Function: const char * gnutls_strerror (int ERROR)
     ERROR: is a GnuTLS error code, a negative error code

     This function is similar to strerror.  The difference is that it
     accepts an error number returned by a gnutls function; In case of
     an unknown error a descriptive string is sent instead of 'NULL' .

     Error codes are always a negative error code.

     *Returns:* A string explaining the GnuTLS error message.

gnutls_strerror_name
--------------------

 -- Function: const char * gnutls_strerror_name (int ERROR)
     ERROR: is an error returned by a gnutls function.

     Return the GnuTLS error code define as a string.  For example,
     gnutls_strerror_name (GNUTLS_E_DH_PRIME_UNACCEPTABLE) will return
     the string "GNUTLS_E_DH_PRIME_UNACCEPTABLE".

     *Returns:* A string corresponding to the symbol name of the error
     code.

     *Since:* 2.6.0

gnutls_supplemental_get_name
----------------------------

 -- Function: const char * gnutls_supplemental_get_name
          (gnutls_supplemental_data_format_type_t TYPE)
     TYPE: is a supplemental data format type

     Convert a 'gnutls_supplemental_data_format_type_t' value to a
     string.

     *Returns:* a string that contains the name of the specified
     supplemental data format type, or 'NULL' for unknown types.

gnutls_tdb_deinit
-----------------

 -- Function: void gnutls_tdb_deinit (gnutls_tdb_t TDB)
     TDB: The structure to be deinitialized

     This function will deinitialize a public key trust storage
     structure.

gnutls_tdb_init
---------------

 -- Function: int gnutls_tdb_init (gnutls_tdb_t * TDB)
     TDB: The structure to be initialized

     This function will initialize a public key trust storage structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_tdb_set_store_commitment_func
------------------------------------

 -- Function: void gnutls_tdb_set_store_commitment_func (gnutls_tdb_t
          TDB, gnutls_tdb_store_commitment_func CSTORE)
     TDB: The trust storage

     CSTORE: The commitment storage function

     This function will associate a commitment (hash) storage function
     with the trust storage structure.  The function is of the following
     form.

     int gnutls_tdb_store_commitment_func(const char* db_name, const
     char* host, const char* service, time_t expiration,
     gnutls_digest_algorithm_t, const gnutls_datum_t* hash);

     The 'db_name' should be used to pass any private data to this
     function.

gnutls_tdb_set_store_func
-------------------------

 -- Function: void gnutls_tdb_set_store_func (gnutls_tdb_t TDB,
          gnutls_tdb_store_func STORE)
     TDB: The trust storage

     STORE: The storage function

     This function will associate a storage function with the trust
     storage structure.  The function is of the following form.

     int gnutls_tdb_store_func(const char* db_name, const char* host,
     const char* service, time_t expiration, const gnutls_datum_t*
     pubkey);

     The 'db_name' should be used to pass any private data to this
     function.

gnutls_tdb_set_verify_func
--------------------------

 -- Function: void gnutls_tdb_set_verify_func (gnutls_tdb_t TDB,
          gnutls_tdb_verify_func VERIFY)
     TDB: The trust storage

     VERIFY: The verification function

     This function will associate a retrieval function with the trust
     storage structure.  The function is of the following form.

     int gnutls_tdb_verify_func(const char* db_name, const char* host,
     const char* service, const gnutls_datum_t* pubkey);

     The verify function should return zero on a match,
     'GNUTLS_E_CERTIFICATE_KEY_MISMATCH' if there is a mismatch and any
     other negative error code otherwise.

     The 'db_name' should be used to pass any private data to this
     function.

gnutls_transport_get_int
------------------------

 -- Function: int gnutls_transport_get_int (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Used to get the first argument of the transport function (like PUSH
     and PULL). This must have been set using
     'gnutls_transport_set_int()' .

     *Returns:* The first argument of the transport function.

     *Since:* 3.1.9

gnutls_transport_get_int2
-------------------------

 -- Function: void gnutls_transport_get_int2 (gnutls_session_t SESSION,
          int * RECV_INT, int * SEND_INT)
     SESSION: is a 'gnutls_session_t' structure.

     RECV_INT: will hold the value for the pull function

     SEND_INT: will hold the value for the push function

     Used to get the arguments of the transport functions (like PUSH and
     PULL). These should have been set using
     'gnutls_transport_set_int2()' .

     *Since:* 3.1.9

gnutls_transport_get_ptr
------------------------

 -- Function: gnutls_transport_ptr_t gnutls_transport_get_ptr
          (gnutls_session_t SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Used to get the first argument of the transport function (like PUSH
     and PULL). This must have been set using
     'gnutls_transport_set_ptr()' .

     *Returns:* The first argument of the transport function.

gnutls_transport_get_ptr2
-------------------------

 -- Function: void gnutls_transport_get_ptr2 (gnutls_session_t SESSION,
          gnutls_transport_ptr_t * RECV_PTR, gnutls_transport_ptr_t *
          SEND_PTR)
     SESSION: is a 'gnutls_session_t' structure.

     RECV_PTR: will hold the value for the pull function

     SEND_PTR: will hold the value for the push function

     Used to get the arguments of the transport functions (like PUSH and
     PULL). These should have been set using
     'gnutls_transport_set_ptr2()' .

gnutls_transport_set_errno
--------------------------

 -- Function: void gnutls_transport_set_errno (gnutls_session_t SESSION,
          int ERR)
     SESSION: is a 'gnutls_session_t' structure.

     ERR: error value to store in session-specific errno variable.

     Store 'err' in the session-specific errno variable.  Useful values
     for 'err' are EINTR, EAGAIN and EMSGSIZE, other values are treated
     will be treated as real errors in the push/pull function.

     This function is useful in replacement push and pull functions set
     by 'gnutls_transport_set_push_function()' and
     'gnutls_transport_set_pull_function()' under Windows, where the
     replacements may not have access to the same 'errno' variable that
     is used by GnuTLS (e.g., the application is linked to msvcr71.dll
     and gnutls is linked to msvcrt.dll).

gnutls_transport_set_errno_function
-----------------------------------

 -- Function: void gnutls_transport_set_errno_function (gnutls_session_t
          SESSION, gnutls_errno_func ERRNO_FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     ERRNO_FUNC: a callback function similar to 'write()'

     This is the function where you set a function to retrieve errno
     after a failed push or pull operation.

     'errno_func' is of the form, int
     (*gnutls_errno_func)(gnutls_transport_ptr_t); and should return the
     errno.

     *Since:* 2.12.0

gnutls_transport_set_int
------------------------

 -- Function: void gnutls_transport_set_int (gnutls_session_t SESSION,
          int I)
     SESSION: is a 'gnutls_session_t' structure.

     I: is the value.

     Used to set the first argument of the transport function (for push
     and pull callbacks) for berkeley style sockets.

     *Since:* 3.1.9

gnutls_transport_set_int2
-------------------------

 -- Function: void gnutls_transport_set_int2 (gnutls_session_t SESSION,
          int RECV_INT, int SEND_INT)
     SESSION: is a 'gnutls_session_t' structure.

     RECV_INT: is the value for the pull function

     SEND_INT: is the value for the push function

     Used to set the first argument of the transport function (for push
     and pull callbacks), when using the berkeley style sockets.  With
     this function you can set two different pointers for receiving and
     sending.

     *Since:* 3.1.9

gnutls_transport_set_ptr
------------------------

 -- Function: void gnutls_transport_set_ptr (gnutls_session_t SESSION,
          gnutls_transport_ptr_t PTR)
     SESSION: is a 'gnutls_session_t' structure.

     PTR: is the value.

     Used to set the first argument of the transport function (for push
     and pull callbacks).  In berkeley style sockets this function will
     set the connection descriptor.

gnutls_transport_set_ptr2
-------------------------

 -- Function: void gnutls_transport_set_ptr2 (gnutls_session_t SESSION,
          gnutls_transport_ptr_t RECV_PTR, gnutls_transport_ptr_t
          SEND_PTR)
     SESSION: is a 'gnutls_session_t' structure.

     RECV_PTR: is the value for the pull function

     SEND_PTR: is the value for the push function

     Used to set the first argument of the transport function (for push
     and pull callbacks).  In berkeley style sockets this function will
     set the connection descriptor.  With this function you can use two
     different pointers for receiving and sending.

gnutls_transport_set_pull_function
----------------------------------

 -- Function: void gnutls_transport_set_pull_function (gnutls_session_t
          SESSION, gnutls_pull_func PULL_FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     PULL_FUNC: a callback function similar to 'read()'

     This is the function where you set a function for gnutls to receive
     data.  Normally, if you use berkeley style sockets, do not need to
     use this function since the default recv(2) will probably be ok.
     The callback should return 0 on connection termination, a positive
     number indicating the number of bytes received, and -1 on error.

     'gnutls_pull_func' is of the form, ssize_t
     (*gnutls_pull_func)(gnutls_transport_ptr_t, void*, size_t);

gnutls_transport_set_pull_timeout_function
------------------------------------------

 -- Function: void gnutls_transport_set_pull_timeout_function
          (gnutls_session_t SESSION, gnutls_pull_timeout_func FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     FUNC: a callback function

     This is the function where you set a function for gnutls to know
     whether data are ready to be received.  It should wait for data a
     given time frame in milliseconds.  The callback should return 0 on
     timeout, a positive number if data can be received, and -1 on
     error.  You'll need to override this function if 'select()' is not
     suitable for the provided transport calls.

     As with 'select()' , if the timeout value is zero the callback
     should return zero if no data are immediately available.

     'gnutls_pull_timeout_func' is of the form, int
     (*gnutls_pull_timeout_func)(gnutls_transport_ptr_t, unsigned int
     ms);

     *Since:* 3.0

gnutls_transport_set_push_function
----------------------------------

 -- Function: void gnutls_transport_set_push_function (gnutls_session_t
          SESSION, gnutls_push_func PUSH_FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     PUSH_FUNC: a callback function similar to 'write()'

     This is the function where you set a push function for gnutls to
     use in order to send data.  If you are going to use berkeley style
     sockets, you do not need to use this function since the default
     send(2) will probably be ok.  Otherwise you should specify this
     function for gnutls to be able to send data.  The callback should
     return a positive number indicating the bytes sent, and -1 on
     error.

     'push_func' is of the form, ssize_t
     (*gnutls_push_func)(gnutls_transport_ptr_t, const void*, size_t);

gnutls_transport_set_vec_push_function
--------------------------------------

 -- Function: void gnutls_transport_set_vec_push_function
          (gnutls_session_t SESSION, gnutls_vec_push_func VEC_FUNC)
     SESSION: is a 'gnutls_session_t' structure.

     VEC_FUNC: a callback function similar to 'writev()'

     Using this function you can override the default writev(2) function
     for gnutls to send data.  Setting this callback instead of
     'gnutls_transport_set_push_function()' is recommended since it
     introduces less overhead in the TLS handshake process.

     'vec_func' is of the form, ssize_t (*gnutls_vec_push_func)
     (gnutls_transport_ptr_t, const giovec_t * iov, int iovcnt);

     *Since:* 2.12.0

gnutls_url_is_supported
-----------------------

 -- Function: int gnutls_url_is_supported (const char * URL)
     URL: A PKCS 11 url

     Check whether url is supported.  Depending on the system libraries
     GnuTLS may support pkcs11 or tpmkey URLs.

     *Returns:* return non-zero if the given URL is supported, and zero
     if it is not known.

     *Since:* 3.1.0

gnutls_verify_stored_pubkey
---------------------------

 -- Function: int gnutls_verify_stored_pubkey (const char * DB_NAME,
          gnutls_tdb_t TDB, const char * HOST, const char * SERVICE,
          gnutls_certificate_type_t CERT_TYPE, const gnutls_datum_t *
          CERT, unsigned int FLAGS)
     DB_NAME: A file specifying the stored keys (use NULL for the
     default)

     TDB: A storage structure or NULL to use the default

     HOST: The peer's name

     SERVICE: non-NULL if this key is specific to a service (e.g.  http)

     CERT_TYPE: The type of the certificate

     CERT: The raw (der) data of the certificate

     FLAGS: should be 0.

     This function will try to verify the provided (raw or DER-encoded)
     certificate using a list of stored public keys.  The 'service'
     field if non-NULL should be a port number.

     The 'retrieve' variable if non-null specifies a custom backend for
     the retrieval of entries.  If it is NULL then the default file
     backend will be used.  In POSIX-like systems the file backend uses
     the $HOME/.gnutls/known_hosts file.

     Note that if the custom storage backend is provided the retrieval
     function should return 'GNUTLS_E_CERTIFICATE_KEY_MISMATCH' if the
     host/service pair is found but key doesn't match,
     'GNUTLS_E_NO_CERTIFICATE_FOUND' if no such host/service with the
     given key is found, and 0 if it was found.  The storage function
     should return 0 on success.

     *Returns:* If no associated public key is found then
     'GNUTLS_E_NO_CERTIFICATE_FOUND' will be returned.  If a key is
     found but does not match 'GNUTLS_E_CERTIFICATE_KEY_MISMATCH' is
     returned.  On success, 'GNUTLS_E_SUCCESS' (0) is returned, or a
     negative error value on other errors.

     *Since:* 3.0.13


File: gnutls.info,  Node: Datagram TLS API,  Next: X509 certificate API,  Prev: Core TLS API,  Up: API reference

E.2 Datagram TLS API
====================

The prototypes for the following functions lie in 'gnutls/dtls.h'.

gnutls_dtls_cookie_send
-----------------------

 -- Function: int gnutls_dtls_cookie_send (gnutls_datum_t * KEY, void *
          CLIENT_DATA, size_t CLIENT_DATA_SIZE, gnutls_dtls_prestate_st
          * PRESTATE, gnutls_transport_ptr_t PTR, gnutls_push_func
          PUSH_FUNC)
     KEY: is a random key to be used at cookie generation

     CLIENT_DATA: contains data identifying the client (i.e.  address)

     CLIENT_DATA_SIZE: The size of client's data

     PRESTATE: The previous cookie returned by
     'gnutls_dtls_cookie_verify()'

     PTR: A transport pointer to be used by 'push_func'

     PUSH_FUNC: A function that will be used to reply

     This function can be used to prevent denial of service attacks to a
     DTLS server by requiring the client to reply using a cookie sent by
     this function.  That way it can be ensured that a client we
     allocated resources for (i.e.  'gnutls_session_t' ) is the one that
     the original incoming packet was originated from.

     This function must be called at the first incoming packet, prior to
     allocating any resources and must be succeeded by
     'gnutls_dtls_cookie_verify()' .

     *Returns:* the number of bytes sent, or a negative error code.

     *Since:* 3.0

gnutls_dtls_cookie_verify
-------------------------

 -- Function: int gnutls_dtls_cookie_verify (gnutls_datum_t * KEY, void
          * CLIENT_DATA, size_t CLIENT_DATA_SIZE, void * _MSG, size_t
          MSG_SIZE, gnutls_dtls_prestate_st * PRESTATE)
     KEY: is a random key to be used at cookie generation

     CLIENT_DATA: contains data identifying the client (i.e.  address)

     CLIENT_DATA_SIZE: The size of client's data

     _MSG: An incoming message that initiates a connection.

     MSG_SIZE: The size of the message.

     PRESTATE: The cookie of this client.

     This function will verify the received message for a valid cookie.
     If a valid cookie is returned then it should be associated with the
     session using 'gnutls_dtls_prestate_set()' ;

     This function must be called after 'gnutls_dtls_cookie_send()' .

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

     *Since:* 3.0

gnutls_dtls_get_data_mtu
------------------------

 -- Function: unsigned int gnutls_dtls_get_data_mtu (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function will return the actual maximum transfer unit for
     application data.  I.e.  DTLS headers are subtracted from the
     actual MTU which is set using 'gnutls_dtls_set_mtu()' .

     *Returns:* the maximum allowed transfer unit.

     *Since:* 3.0

gnutls_dtls_get_mtu
-------------------

 -- Function: unsigned int gnutls_dtls_get_mtu (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function will return the MTU size as set with
     'gnutls_dtls_set_mtu()' .  This is not the actual MTU of data you
     can transmit.  Use 'gnutls_dtls_get_data_mtu()' for that reason.

     *Returns:* the set maximum transfer unit.

     *Since:* 3.0

gnutls_dtls_get_timeout
-----------------------

 -- Function: unsigned int gnutls_dtls_get_timeout (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     This function will return the milliseconds remaining for a
     retransmission of the previously sent handshake message.  This
     function is useful when DTLS is used in non-blocking mode, to
     estimate when to call 'gnutls_handshake()' if no packets have been
     received.

     *Returns:* the remaining time in milliseconds.

     *Since:* 3.0

gnutls_dtls_prestate_set
------------------------

 -- Function: void gnutls_dtls_prestate_set (gnutls_session_t SESSION,
          gnutls_dtls_prestate_st * PRESTATE)
     SESSION: a new session

     PRESTATE: contains the client's prestate

     This function will associate the prestate acquired by the cookie
     authentication with the client, with the newly established session.

     This functions must be called after a successful
     'gnutls_dtls_cookie_verify()' and should be succeeded by the actual
     DTLS handshake using 'gnutls_handshake()' .

     *Since:* 3.0

gnutls_dtls_set_data_mtu
------------------------

 -- Function: int gnutls_dtls_set_data_mtu (gnutls_session_t SESSION,
          unsigned int MTU)
     SESSION: is a 'gnutls_session_t' structure.

     MTU: The maximum unencrypted transfer unit of the session

     This function will set the maximum size of the *unencrypted*
     records which will be sent over a DTLS session.  It is equivalent
     to calculating the DTLS packet overhead with the current encryption
     parameters, and calling 'gnutls_dtls_set_mtu()' with that value.
     In particular, this means that you may need to call this function
     again after any negotiation or renegotiation, in order to ensure
     that the MTU is still sufficient to account for the new protocol
     overhead.

     In most cases you only need to call 'gnutls_dtls_set_mtu()' with
     the maximum MTU of your transport layer.

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

     *Since:* 3.1

gnutls_dtls_set_mtu
-------------------

 -- Function: void gnutls_dtls_set_mtu (gnutls_session_t SESSION,
          unsigned int MTU)
     SESSION: is a 'gnutls_session_t' structure.

     MTU: The maximum transfer unit of the transport

     This function will set the maximum transfer unit of the transport
     that DTLS packets are sent over.  Note that this should exclude the
     IP (or IPv6) and UDP headers.  So for DTLS over IPv6 on an Ethenet
     device with MTU 1500, the DTLS MTU set with this function would be
     1500 - 40 (IPV6 header) - 8 (UDP header) = 1452.

     *Since:* 3.0

gnutls_dtls_set_timeouts
------------------------

 -- Function: void gnutls_dtls_set_timeouts (gnutls_session_t SESSION,
          unsigned int RETRANS_TIMEOUT, unsigned int TOTAL_TIMEOUT)
     SESSION: is a 'gnutls_session_t' structure.

     RETRANS_TIMEOUT: The time at which a retransmission will occur in
     milliseconds

     TOTAL_TIMEOUT: The time at which the connection will be aborted, in
     milliseconds.

     This function will set the timeouts required for the DTLS handshake
     protocol.  The retransmission timeout is the time after which a
     message from the peer is not received, the previous messages will
     be retransmitted.  The total timeout is the time after which the
     handshake will be aborted with 'GNUTLS_E_TIMEDOUT' .

     The DTLS protocol recommends the values of 1 sec and 60 seconds
     respectively.

     To disable retransmissions set a 'retrans_timeout' larger than the
     'total_timeout' .

     *Since:* 3.0

gnutls_record_get_discarded
---------------------------

 -- Function: unsigned int gnutls_record_get_discarded (gnutls_session_t
          SESSION)
     SESSION: is a 'gnutls_session_t' structure.

     Returns the number of discarded packets in a DTLS connection.

     *Returns:* The number of discarded packets.

     *Since:* 3.0


File: gnutls.info,  Node: X509 certificate API,  Next: OCSP API,  Prev: Datagram TLS API,  Up: API reference

E.3 X.509 certificate API
=========================

The following functions are to be used for X.509 certificate handling.
Their prototypes lie in 'gnutls/x509.h'.

gnutls_certificate_set_trust_list
---------------------------------

 -- Function: void gnutls_certificate_set_trust_list
          (gnutls_certificate_credentials_t RES,
          gnutls_x509_trust_list_t TLIST, unsigned FLAGS)
     RES: is a 'gnutls_certificate_credentials_t' structure.

     TLIST: is a 'gnutls_x509_trust_list_t' structure

     FLAGS: must be zero

     This function sets a trust list in the
     gnutls_certificate_credentials_t structure.

     Note that the 'tlist' will become part of the credentials structure
     and must not be deallocated.  It will be automatically deallocated
     when the 'res' structure is deinitialized.

     *Returns:* 'GNUTLS_E_SUCCESS' (0) on success, or a negative error
     code.

     *Since:* 3.2.2

gnutls_pkcs7_deinit
-------------------

 -- Function: void gnutls_pkcs7_deinit (gnutls_pkcs7_t PKCS7)
     PKCS7: The structure to be initialized

     This function will deinitialize a PKCS7 structure.

gnutls_pkcs7_delete_crl
-----------------------

 -- Function: int gnutls_pkcs7_delete_crl (gnutls_pkcs7_t PKCS7, int
          INDX)
     PKCS7: should contain a 'gnutls_pkcs7_t' structure

     INDX: the index of the crl to delete

     This function will delete a crl from a PKCS7 or RFC2630 crl set.
     Index starts from 0.  Returns 0 on success.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_delete_crt
-----------------------

 -- Function: int gnutls_pkcs7_delete_crt (gnutls_pkcs7_t PKCS7, int
          INDX)
     PKCS7: should contain a gnutls_pkcs7_t structure

     INDX: the index of the certificate to delete

     This function will delete a certificate from a PKCS7 or RFC2630
     certificate set.  Index starts from 0.  Returns 0 on success.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_export
-------------------

 -- Function: int gnutls_pkcs7_export (gnutls_pkcs7_t PKCS7,
          gnutls_x509_crt_fmt_t FORMAT, void * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     PKCS7: Holds the pkcs7 structure

     FORMAT: the format of output params.  One of PEM or DER.

     OUTPUT_DATA: will contain a structure PEM or DER encoded

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will export the pkcs7 structure to DER or PEM format.

     If the buffer provided is not long enough to hold the output, then
     * 'output_data_size' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER'
     will be returned.

     If the structure is PEM encoded, it will have a header of "BEGIN
     PKCS7".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_export2
--------------------

 -- Function: int gnutls_pkcs7_export2 (gnutls_pkcs7_t PKCS7,
          gnutls_x509_crt_fmt_t FORMAT, gnutls_datum_t * OUT)
     PKCS7: Holds the pkcs7 structure

     FORMAT: the format of output params.  One of PEM or DER.

     OUT: will contain a structure PEM or DER encoded

     This function will export the pkcs7 structure to DER or PEM format.

     The output buffer is allocated using 'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN
     PKCS7".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.1.3

gnutls_pkcs7_get_crl_count
--------------------------

 -- Function: int gnutls_pkcs7_get_crl_count (gnutls_pkcs7_t PKCS7)
     PKCS7: should contain a gnutls_pkcs7_t structure

     This function will return the number of certifcates in the PKCS7 or
     RFC2630 crl set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_get_crl_raw
------------------------

 -- Function: int gnutls_pkcs7_get_crl_raw (gnutls_pkcs7_t PKCS7, int
          INDX, void * CRL, size_t * CRL_SIZE)
     PKCS7: should contain a 'gnutls_pkcs7_t' structure

     INDX: contains the index of the crl to extract

     CRL: the contents of the crl will be copied there (may be null)

     CRL_SIZE: should hold the size of the crl

     This function will return a crl of the PKCS7 or RFC2630 crl set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  If the provided buffer is not
     long enough, then 'crl_size' is updated and
     'GNUTLS_E_SHORT_MEMORY_BUFFER' is returned.  After the last crl has
     been read 'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

gnutls_pkcs7_get_crt_count
--------------------------

 -- Function: int gnutls_pkcs7_get_crt_count (gnutls_pkcs7_t PKCS7)
     PKCS7: should contain a 'gnutls_pkcs7_t' structure

     This function will return the number of certifcates in the PKCS7 or
     RFC2630 certificate set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_get_crt_raw
------------------------

 -- Function: int gnutls_pkcs7_get_crt_raw (gnutls_pkcs7_t PKCS7, int
          INDX, void * CERTIFICATE, size_t * CERTIFICATE_SIZE)
     PKCS7: should contain a gnutls_pkcs7_t structure

     INDX: contains the index of the certificate to extract

     CERTIFICATE: the contents of the certificate will be copied there
     (may be null)

     CERTIFICATE_SIZE: should hold the size of the certificate

     This function will return a certificate of the PKCS7 or RFC2630
     certificate set.

     After the last certificate has been read
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  If the provided buffer is not
     long enough, then 'certificate_size' is updated and
     'GNUTLS_E_SHORT_MEMORY_BUFFER' is returned.

gnutls_pkcs7_import
-------------------

 -- Function: int gnutls_pkcs7_import (gnutls_pkcs7_t PKCS7, const
          gnutls_datum_t * DATA, gnutls_x509_crt_fmt_t FORMAT)
     PKCS7: The structure to store the parsed PKCS7.

     DATA: The DER or PEM encoded PKCS7.

     FORMAT: One of DER or PEM

     This function will convert the given DER or PEM encoded PKCS7 to
     the native 'gnutls_pkcs7_t' format.  The output will be stored in
     'pkcs7' .

     If the PKCS7 is PEM encoded it should have a header of "PKCS7".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_init
-----------------

 -- Function: int gnutls_pkcs7_init (gnutls_pkcs7_t * PKCS7)
     PKCS7: The structure to be initialized

     This function will initialize a PKCS7 structure.  PKCS7 structures
     usually contain lists of X.509 Certificates and X.509 Certificate
     revocation lists.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_set_crl
--------------------

 -- Function: int gnutls_pkcs7_set_crl (gnutls_pkcs7_t PKCS7,
          gnutls_x509_crl_t CRL)
     PKCS7: should contain a 'gnutls_pkcs7_t' structure

     CRL: the DER encoded crl to be added

     This function will add a parsed CRL to the PKCS7 or RFC2630 crl
     set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_set_crl_raw
------------------------

 -- Function: int gnutls_pkcs7_set_crl_raw (gnutls_pkcs7_t PKCS7, const
          gnutls_datum_t * CRL)
     PKCS7: should contain a 'gnutls_pkcs7_t' structure

     CRL: the DER encoded crl to be added

     This function will add a crl to the PKCS7 or RFC2630 crl set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_set_crt
--------------------

 -- Function: int gnutls_pkcs7_set_crt (gnutls_pkcs7_t PKCS7,
          gnutls_x509_crt_t CRT)
     PKCS7: should contain a 'gnutls_pkcs7_t' structure

     CRT: the certificate to be copied.

     This function will add a parsed certificate to the PKCS7 or RFC2630
     certificate set.  This is a wrapper function over
     'gnutls_pkcs7_set_crt_raw()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_pkcs7_set_crt_raw
------------------------

 -- Function: int gnutls_pkcs7_set_crt_raw (gnutls_pkcs7_t PKCS7, const
          gnutls_datum_t * CRT)
     PKCS7: should contain a 'gnutls_pkcs7_t' structure

     CRT: the DER encoded certificate to be added

     This function will add a certificate to the PKCS7 or RFC2630
     certificate set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_subject_alt_names_deinit
-------------------------------

 -- Function: void gnutls_subject_alt_names_deinit
          (gnutls_subject_alt_names_t SANS)
     SANS: The alternative names structure

     This function will deinitialize an alternative names structure.

     *Since:* 3.3.0

gnutls_subject_alt_names_get
----------------------------

 -- Function: int gnutls_subject_alt_names_get
          (gnutls_subject_alt_names_t SANS, unsigned int SEQ, unsigned
          int * SAN_TYPE, gnutls_datum_t * SAN, gnutls_datum_t *
          OTHERNAME_OID)
     SANS: The alternative names structure

     SEQ: The index of the name to get

     SAN_TYPE: Will hold the type of the name (of
     'gnutls_subject_alt_names_t' )

     SAN: The alternative name data (should be treated as constant)

     OTHERNAME_OID: The object identifier if 'san_type' is
     'GNUTLS_SAN_OTHERNAME' (should be treated as constant)

     This function will return a specific alternative name as stored in
     the 'sans' structure.  The returned values should be treated as
     constant and valid for the lifetime of 'sans' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the index is out of
     bounds, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_subject_alt_names_init
-----------------------------

 -- Function: int gnutls_subject_alt_names_init
          (gnutls_subject_alt_names_t * SANS)
     SANS: The alternative names structure

     This function will initialize an alternative names structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_subject_alt_names_set
----------------------------

 -- Function: int gnutls_subject_alt_names_set
          (gnutls_subject_alt_names_t SANS, unsigned int SAN_TYPE, const
          gnutls_datum_t * SAN, const char * OTHERNAME_OID)
     SANS: The alternative names structure

     SAN_TYPE: The type of the name (of 'gnutls_subject_alt_names_t' )

     SAN: The alternative name data

     OTHERNAME_OID: The object identifier if 'san_type' is
     'GNUTLS_SAN_OTHERNAME'

     This function will store the specified alternative name in the
     'sans' structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0), otherwise a negative
     error value.

     *Since:* 3.3.0

gnutls_x509_aia_deinit
----------------------

 -- Function: void gnutls_x509_aia_deinit (gnutls_x509_aia_t AIA)
     AIA: The authority info access structure

     This function will deinitialize a CRL distribution points
     structure.

     *Since:* 3.3.0

gnutls_x509_aia_get
-------------------

 -- Function: int gnutls_x509_aia_get (gnutls_x509_aia_t AIA, unsigned
          int SEQ, gnutls_datum_t * OID, unsigned * SAN_TYPE,
          gnutls_datum_t * SAN)
     AIA: The authority info access structure

     SEQ: specifies the sequence number of the access descriptor (0 for
     the first one, 1 for the second etc.)

     OID: the type of available data; to be treated as constant.

     SAN_TYPE: Will hold the type of the name of
     'gnutls_subject_alt_names_t' (may be null).

     SAN: the access location name; to be treated as constant (may be
     null).

     This function reads from the Authority Information Access
     structure.

     The 'seq' input parameter is used to indicate which member of the
     sequence the caller is interested in.  The first member is 0, the
     second member 1 and so on.  When the 'seq' value is out of bounds,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     Typically 'oid' is 'GNUTLS_OID_AD_CAISSUERS' or
     'GNUTLS_OID_AD_OCSP' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_aia_init
--------------------

 -- Function: int gnutls_x509_aia_init (gnutls_x509_aia_t * AIA)
     AIA: The authority info access structure

     This function will initialize a CRL distribution points structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_aia_set
-------------------

 -- Function: int gnutls_x509_aia_set (gnutls_x509_aia_t AIA, const char
          * OID, unsigned SAN_TYPE, const gnutls_datum_t * SAN)
     AIA: The authority info access structure

     OID: the type of data.

     SAN_TYPE: The type of the name (of 'gnutls_subject_alt_names_t' )

     SAN: The alternative name data

     This function will store the specified alternative name in the
     'aia' structure.

     Typically the value for 'oid' should be 'GNUTLS_OID_AD_OCSP' , or
     'GNUTLS_OID_AD_CAISSUERS' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0), otherwise a negative
     error value.

     *Since:* 3.3.0

gnutls_x509_aki_deinit
----------------------

 -- Function: void gnutls_x509_aki_deinit (gnutls_x509_aki_t AKI)
     AKI: The authority key identifier structure

     This function will deinitialize an authority key identifier
     structure.

     *Since:* 3.3.0

gnutls_x509_aki_get_cert_issuer
-------------------------------

 -- Function: int gnutls_x509_aki_get_cert_issuer (gnutls_x509_aki_t
          AKI, unsigned int SEQ, unsigned int * SAN_TYPE, gnutls_datum_t
          * SAN, gnutls_datum_t * OTHERNAME_OID, gnutls_datum_t *
          SERIAL)
     AKI: The authority key ID structure

     SEQ: The index of the name to get

     SAN_TYPE: Will hold the type of the name (of
     'gnutls_subject_alt_names_t' )

     SAN: The alternative name data

     OTHERNAME_OID: The object identifier if 'san_type' is
     'GNUTLS_SAN_OTHERNAME'

     SERIAL: The authorityCertSerialNumber number

     This function will return a specific authorityCertIssuer name as
     stored in the 'aki' structure, as well as the
     authorityCertSerialNumber.  All the returned values should be
     treated as constant, and may be set to 'NULL' when are not
     required.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the index is out of
     bounds, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_aki_get_id
----------------------

 -- Function: int gnutls_x509_aki_get_id (gnutls_x509_aki_t AKI,
          gnutls_datum_t * ID)
     AKI: The authority key ID structure

     ID: Will hold the identifier

     This function will return the key identifier as stored in the 'aki'
     structure.  The identifier should be treated as constant.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the index is out of
     bounds, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_aki_init
--------------------

 -- Function: int gnutls_x509_aki_init (gnutls_x509_aki_t * AKI)
     AKI: The authority key ID structure

     This function will initialize an authority key ID structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_aki_set_cert_issuer
-------------------------------

 -- Function: int gnutls_x509_aki_set_cert_issuer (gnutls_x509_aki_t
          AKI, unsigned int SAN_TYPE, const gnutls_datum_t * SAN, const
          char * OTHERNAME_OID, const gnutls_datum_t * SERIAL)
     AKI: The authority key ID structure

     SAN_TYPE: the type of the name (of 'gnutls_subject_alt_names_t' ),
     may be null

     SAN: The alternative name data

     OTHERNAME_OID: The object identifier if 'san_type' is
     'GNUTLS_SAN_OTHERNAME'

     SERIAL: The authorityCertSerialNumber number (may be null)

     This function will set the authorityCertIssuer name and the
     authorityCertSerialNumber to be stored in the 'aki' structure.
     When storing multiple names, the serial should be set on the first
     call, and subsequent calls should use a 'NULL' serial.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_aki_set_id
----------------------

 -- Function: int gnutls_x509_aki_set_id (gnutls_x509_aki_t AKI, const
          gnutls_datum_t * ID)
     AKI: The authority key ID structure

     ID: the key identifier

     This function will set the keyIdentifier to be stored in the 'aki'
     structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_crl_check_issuer
----------------------------

 -- Function: int gnutls_x509_crl_check_issuer (gnutls_x509_crl_t CRL,
          gnutls_x509_crt_t ISSUER)
     CRL: is the CRL to be checked

     ISSUER: is the certificate of a possible issuer

     This function will check if the given CRL was issued by the given
     issuer certificate.

     *Returns:* true (1) if the given CRL was issued by the given
     issuer, and false (0) if not.

gnutls_x509_crl_deinit
----------------------

 -- Function: void gnutls_x509_crl_deinit (gnutls_x509_crl_t CRL)
     CRL: The structure to be deinitialized

     This function will deinitialize a CRL structure.

gnutls_x509_crl_dist_points_deinit
----------------------------------

 -- Function: void gnutls_x509_crl_dist_points_deinit
          (gnutls_x509_crl_dist_points_t CDP)
     CDP: The CRL distribution points structure

     This function will deinitialize a CRL distribution points
     structure.

     *Since:* 3.3.0

gnutls_x509_crl_dist_points_get
-------------------------------

 -- Function: int gnutls_x509_crl_dist_points_get
          (gnutls_x509_crl_dist_points_t CDP, unsigned int SEQ, unsigned
          int * TYPE, gnutls_datum_t * SAN, unsigned int * REASONS)
     CDP: The CRL distribution points structure

     SEQ: specifies the sequence number of the distribution point (0 for
     the first one, 1 for the second etc.)

     TYPE: The name type of the corresponding name
     (gnutls_x509_subject_alt_name_t)

     SAN: The distribution point names (to be treated as constant)

     REASONS: Revocation reasons.  An ORed sequence of flags from
     'gnutls_x509_crl_reason_flags_t' .

     This function retrieves the individual CRL distribution points
     (2.5.29.31), contained in provided structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the index is out of
     bounds, otherwise a negative error value.

gnutls_x509_crl_dist_points_init
--------------------------------

 -- Function: int gnutls_x509_crl_dist_points_init
          (gnutls_x509_crl_dist_points_t * CDP)
     CDP: The CRL distribution points structure

     This function will initialize a CRL distribution points structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_crl_dist_points_set
-------------------------------

 -- Function: int gnutls_x509_crl_dist_points_set
          (gnutls_x509_crl_dist_points_t CDP,
          gnutls_x509_subject_alt_name_t TYPE, const gnutls_datum_t *
          SAN, unsigned int REASONS)
     CDP: The CRL distribution points structure

     TYPE: The type of the name (of 'gnutls_subject_alt_names_t' )

     SAN: The point name data

     REASONS: Revocation reasons.  An ORed sequence of flags from
     'gnutls_x509_crl_reason_flags_t' .

     This function will store the specified CRL distibution point value
     the 'cdp' structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0), otherwise a negative
     error value.

     *Since:* 3.3.0

gnutls_x509_crl_export
----------------------

 -- Function: int gnutls_x509_crl_export (gnutls_x509_crl_t CRL,
          gnutls_x509_crt_fmt_t FORMAT, void * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     CRL: Holds the revocation list

     FORMAT: the format of output params.  One of PEM or DER.

     OUTPUT_DATA: will contain a private key PEM or DER encoded

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will export the revocation list to DER or PEM format.

     If the buffer provided is not long enough to hold the output, then
     'GNUTLS_E_SHORT_MEMORY_BUFFER' will be returned.

     If the structure is PEM encoded, it will have a header of "BEGIN
     X509 CRL".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_export2
-----------------------

 -- Function: int gnutls_x509_crl_export2 (gnutls_x509_crl_t CRL,
          gnutls_x509_crt_fmt_t FORMAT, gnutls_datum_t * OUT)
     CRL: Holds the revocation list

     FORMAT: the format of output params.  One of PEM or DER.

     OUT: will contain a private key PEM or DER encoded

     This function will export the revocation list to DER or PEM format.

     The output buffer is allocated using 'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN
     X509 CRL".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     Since 3.1.3

gnutls_x509_crl_get_authority_key_gn_serial
-------------------------------------------

 -- Function: int gnutls_x509_crl_get_authority_key_gn_serial
          (gnutls_x509_crl_t CRL, unsigned int SEQ, void * ALT, size_t *
          ALT_SIZE, unsigned int * ALT_TYPE, void * SERIAL, size_t *
          SERIAL_SIZE, unsigned int * CRITICAL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     ALT: is the place where the alternative name will be copied to

     ALT_SIZE: holds the size of alt.

     ALT_TYPE: holds the type of the alternative name (one of
     gnutls_x509_subject_alt_name_t).

     SERIAL: buffer to store the serial number (may be null)

     SERIAL_SIZE: Holds the size of the serial field (may be null)

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the X.509 authority key identifier when
     stored as a general name (authorityCertIssuer) and serial number.

     Because more than one general names might be stored 'seq' can be
     used as a counter to request them all until
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Returns:* Returns 0 on success, or an error code.

     *Since:* 3.0

gnutls_x509_crl_get_authority_key_id
------------------------------------

 -- Function: int gnutls_x509_crl_get_authority_key_id
          (gnutls_x509_crl_t CRL, void * ID, size_t * ID_SIZE, unsigned
          int * CRITICAL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     ID: The place where the identifier will be copied

     ID_SIZE: Holds the size of the result field.

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the CRL authority's key identifier.  This
     is obtained by the X.509 Authority Key identifier extension field
     (2.5.29.35).  Note that this function only returns the
     keyIdentifier field of the extension and
     'GNUTLS_E_X509_UNSUPPORTED_EXTENSION' , if the extension contains
     the name and serial number of the certificate.  In that case
     'gnutls_x509_crl_get_authority_key_gn_serial()' may be used.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.

     *Since:* 2.8.0

gnutls_x509_crl_get_crt_count
-----------------------------

 -- Function: int gnutls_x509_crl_get_crt_count (gnutls_x509_crl_t CRL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     This function will return the number of revoked certificates in the
     given CRL.

     *Returns:* number of certificates, a negative error code on
     failure.

gnutls_x509_crl_get_crt_serial
------------------------------

 -- Function: int gnutls_x509_crl_get_crt_serial (gnutls_x509_crl_t CRL,
          int INDX, unsigned char * SERIAL, size_t * SERIAL_SIZE, time_t
          * T)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     INDX: the index of the certificate to extract (starting from 0)

     SERIAL: where the serial number will be copied

     SERIAL_SIZE: initially holds the size of serial

     T: if non null, will hold the time this certificate was revoked

     This function will retrieve the serial number of the specified, by
     the index, revoked certificate.

     Note that this function will have performance issues in large
     sequences of revoked certificates.  In that case use
     'gnutls_x509_crl_iter_crt_serial()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_get_dn_oid
--------------------------

 -- Function: int gnutls_x509_crl_get_dn_oid (gnutls_x509_crl_t CRL, int
          INDX, void * OID, size_t * SIZEOF_OID)
     CRL: should contain a gnutls_x509_crl_t structure

     INDX: Specifies which DN OID to send.  Use (0) to get the first
     one.

     OID: a pointer to a structure to hold the name (may be null)

     SIZEOF_OID: initially holds the size of 'oid'

     This function will extract the requested OID of the name of the CRL
     issuer, specified by the given index.

     If oid is null then only the size will be filled.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the sizeof_oid will be updated
     with the required size.  On success 0 is returned.

gnutls_x509_crl_get_extension_data
----------------------------------

 -- Function: int gnutls_x509_crl_get_extension_data (gnutls_x509_crl_t
          CRL, int INDX, void * DATA, size_t * SIZEOF_DATA)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     INDX: Specifies which extension OID to send.  Use (0) to get the
     first one.

     DATA: a pointer to a structure to hold the data (may be null)

     SIZEOF_DATA: initially holds the size of 'oid'

     This function will return the requested extension data in the CRL.
     The extension data will be stored as a string in the provided
     buffer.

     Use 'gnutls_x509_crl_get_extension_info()' to extract the OID and
     critical flag.  Use 'gnutls_x509_crl_get_extension_info()' instead,
     if you want to get data indexed by the extension OID rather than
     sequence.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If your have
     reached the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crl_get_extension_data2
-----------------------------------

 -- Function: int gnutls_x509_crl_get_extension_data2 (gnutls_x509_crl_t
          CRL, unsigned INDX, gnutls_datum_t * DATA)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     INDX: Specifies which extension OID to read.  Use (0) to get the
     first one.

     DATA: will contain the extension DER-encoded data

     This function will return the requested by the index extension data
     in the certificate revocation list.  The extension data will be
     allocated using 'gnutls_malloc()' .

     Use 'gnutls_x509_crt_get_extension_info()' to extract the OID.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If you have reached
     the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

gnutls_x509_crl_get_extension_info
----------------------------------

 -- Function: int gnutls_x509_crl_get_extension_info (gnutls_x509_crl_t
          CRL, int INDX, void * OID, size_t * SIZEOF_OID, unsigned int *
          CRITICAL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     INDX: Specifies which extension OID to send, use (0) to get the
     first one.

     OID: a pointer to a structure to hold the OID

     SIZEOF_OID: initially holds the maximum size of 'oid' , on return
     holds actual size of 'oid' .

     CRITICAL: output variable with critical flag, may be NULL.

     This function will return the requested extension OID in the CRL,
     and the critical flag for it.  The extension OID will be stored as
     a string in the provided buffer.  Use
     'gnutls_x509_crl_get_extension_data()' to extract the data.

     If the buffer provided is not long enough to hold the output, then
     * 'sizeof_oid' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER' will
     be returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If your have
     reached the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crl_get_extension_oid
---------------------------------

 -- Function: int gnutls_x509_crl_get_extension_oid (gnutls_x509_crl_t
          CRL, int INDX, void * OID, size_t * SIZEOF_OID)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     INDX: Specifies which extension OID to send, use (0) to get the
     first one.

     OID: a pointer to a structure to hold the OID (may be null)

     SIZEOF_OID: initially holds the size of 'oid'

     This function will return the requested extension OID in the CRL.
     The extension OID will be stored as a string in the provided
     buffer.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If your have
     reached the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crl_get_issuer_dn
-----------------------------

 -- Function: int gnutls_x509_crl_get_issuer_dn (const gnutls_x509_crl_t
          CRL, char * BUF, size_t * SIZEOF_BUF)
     CRL: should contain a gnutls_x509_crl_t structure

     BUF: a pointer to a structure to hold the peer's name (may be null)

     SIZEOF_BUF: initially holds the size of 'buf'

     This function will copy the name of the CRL issuer in the provided
     buffer.  The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
     described in RFC4514.  The output string will be ASCII or UTF-8
     encoded, depending on the certificate data.

     If buf is 'NULL' then only the size will be filled.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the sizeof_buf will be updated
     with the required size, and 0 on success.

gnutls_x509_crl_get_issuer_dn2
------------------------------

 -- Function: int gnutls_x509_crl_get_issuer_dn2 (gnutls_x509_crl_t CRL,
          gnutls_datum_t * DN)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     DN: a pointer to a structure to hold the name

     This function will allocate buffer and copy the name of the CRL
     issuer.  The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
     described in RFC4514.  The output string will be ASCII or UTF-8
     encoded, depending on the certificate data.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.1.10

gnutls_x509_crl_get_issuer_dn_by_oid
------------------------------------

 -- Function: int gnutls_x509_crl_get_issuer_dn_by_oid
          (gnutls_x509_crl_t CRL, const char * OID, int INDX, unsigned
          int RAW_FLAG, void * BUF, size_t * SIZEOF_BUF)
     CRL: should contain a gnutls_x509_crl_t structure

     OID: holds an Object Identified in null terminated string

     INDX: In case multiple same OIDs exist in the RDN, this specifies
     which to send.  Use (0) to get the first one.

     RAW_FLAG: If non-zero returns the raw DER data of the DN part.

     BUF: a pointer to a structure to hold the peer's name (may be null)

     SIZEOF_BUF: initially holds the size of 'buf'

     This function will extract the part of the name of the CRL issuer
     specified by the given OID. The output will be encoded as described
     in RFC4514.  The output string will be ASCII or UTF-8 encoded,
     depending on the certificate data.

     Some helper macros with popular OIDs can be found in gnutls/x509.h
     If raw flag is (0), this function will only return known OIDs as
     text.  Other OIDs will be DER encoded, as described in RFC4514 - in
     hex format with a '#' prefix.  You can check about known OIDs using
     'gnutls_x509_dn_oid_known()' .

     If buf is null then only the size will be filled.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the sizeof_buf will be updated
     with the required size, and 0 on success.

gnutls_x509_crl_get_next_update
-------------------------------

 -- Function: time_t gnutls_x509_crl_get_next_update (gnutls_x509_crl_t
          CRL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     This function will return the time the next CRL will be issued.
     This field is optional in a CRL so it might be normal to get an
     error instead.

     *Returns:* when the next CRL will be issued, or (time_t)-1 on
     error.

gnutls_x509_crl_get_number
--------------------------

 -- Function: int gnutls_x509_crl_get_number (gnutls_x509_crl_t CRL,
          void * RET, size_t * RET_SIZE, unsigned int * CRITICAL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     RET: The place where the number will be copied

     RET_SIZE: Holds the size of the result field.

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the CRL number extension.  This is
     obtained by the CRL Number extension field (2.5.29.20).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.

     *Since:* 2.8.0

gnutls_x509_crl_get_raw_issuer_dn
---------------------------------

 -- Function: int gnutls_x509_crl_get_raw_issuer_dn (gnutls_x509_crl_t
          CRL, gnutls_datum_t * DN)
     CRL: should contain a gnutls_x509_crl_t structure

     DN: will hold the starting point of the DN

     This function will return a pointer to the DER encoded DN structure
     and the length.

     *Returns:* a negative error code on error, and (0) on success.

     *Since:* 2.12.0

gnutls_x509_crl_get_signature
-----------------------------

 -- Function: int gnutls_x509_crl_get_signature (gnutls_x509_crl_t CRL,
          char * SIG, size_t * SIZEOF_SIG)
     CRL: should contain a gnutls_x509_crl_t structure

     SIG: a pointer where the signature part will be copied (may be
     null).

     SIZEOF_SIG: initially holds the size of 'sig'

     This function will extract the signature field of a CRL.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_get_signature_algorithm
---------------------------------------

 -- Function: int gnutls_x509_crl_get_signature_algorithm
          (gnutls_x509_crl_t CRL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     This function will return a value of the 'gnutls_sign_algorithm_t'
     enumeration that is the signature algorithm.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_get_this_update
-------------------------------

 -- Function: time_t gnutls_x509_crl_get_this_update (gnutls_x509_crl_t
          CRL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     This function will return the time this CRL was issued.

     *Returns:* when the CRL was issued, or (time_t)-1 on error.

gnutls_x509_crl_get_version
---------------------------

 -- Function: int gnutls_x509_crl_get_version (gnutls_x509_crl_t CRL)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     This function will return the version of the specified CRL.

     *Returns:* The version number, or a negative error code on error.

gnutls_x509_crl_import
----------------------

 -- Function: int gnutls_x509_crl_import (gnutls_x509_crl_t CRL, const
          gnutls_datum_t * DATA, gnutls_x509_crt_fmt_t FORMAT)
     CRL: The structure to store the parsed CRL.

     DATA: The DER or PEM encoded CRL.

     FORMAT: One of DER or PEM

     This function will convert the given DER or PEM encoded CRL to the
     native 'gnutls_x509_crl_t' format.  The output will be stored in
     'crl'.

     If the CRL is PEM encoded it should have a header of "X509 CRL".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_init
--------------------

 -- Function: int gnutls_x509_crl_init (gnutls_x509_crl_t * CRL)
     CRL: The structure to be initialized

     This function will initialize a CRL structure.  CRL stands for
     Certificate Revocation List.  A revocation list usually contains
     lists of certificate serial numbers that have been revoked by an
     Authority.  The revocation lists are always signed with the
     authority's private key.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_iter_crt_serial
-------------------------------

 -- Function: int gnutls_x509_crl_iter_crt_serial (gnutls_x509_crl_t
          CRL, gnutls_x509_crl_iter_t * ITER, unsigned char * SERIAL,
          size_t * SERIAL_SIZE, time_t * T)
     CRL: should contain a 'gnutls_x509_crl_t' structure

     ITER: A pointer to an iterator (initially the iterator should be
     'NULL' )

     SERIAL: where the serial number will be copied

     SERIAL_SIZE: initially holds the size of serial

     T: if non null, will hold the time this certificate was revoked

     This function performs the same as
     'gnutls_x509_crl_get_crt_serial()' , but reads sequentially and
     keeps state in the iterator between calls.  That allows it to
     provide better performance in sequences with many elements
     (50000+).

     When past the last element is accessed
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned and the
     iterator is reset.

     After use, the iterator must be deinitialized using
     'gnutls_x509_crl_iter_deinit()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_iter_deinit
---------------------------

 -- Function: void gnutls_x509_crl_iter_deinit (gnutls_x509_crl_iter_t
          ITER)
     ITER: The iterator structure to be deinitialized

     This function will deinitialize an iterator structure.

gnutls_x509_crl_list_import
---------------------------

 -- Function: int gnutls_x509_crl_list_import (gnutls_x509_crl_t * CRLS,
          unsigned int * CRL_MAX, const gnutls_datum_t * DATA,
          gnutls_x509_crt_fmt_t FORMAT, unsigned int FLAGS)
     CRLS: The structures to store the parsed CRLs.  Must not be
     initialized.

     CRL_MAX: Initially must hold the maximum number of crls.  It will
     be updated with the number of crls available.

     DATA: The PEM encoded CRLs

     FORMAT: One of DER or PEM.

     FLAGS: must be (0) or an OR'd sequence of
     gnutls_certificate_import_flags.

     This function will convert the given PEM encoded CRL list to the
     native gnutls_x509_crl_t format.  The output will be stored in
     'crls' .  They will be automatically initialized.

     If the Certificate is PEM encoded it should have a header of "X509
     CRL".

     *Returns:* the number of certificates read or a negative error
     value.

     *Since:* 3.0

gnutls_x509_crl_list_import2
----------------------------

 -- Function: int gnutls_x509_crl_list_import2 (gnutls_x509_crl_t **
          CRLS, unsigned int * SIZE, const gnutls_datum_t * DATA,
          gnutls_x509_crt_fmt_t FORMAT, unsigned int FLAGS)
     CRLS: The structures to store the parsed crl list.  Must not be
     initialized.

     SIZE: It will contain the size of the list.

     DATA: The PEM encoded CRL.

     FORMAT: One of DER or PEM.

     FLAGS: must be (0) or an OR'd sequence of
     gnutls_certificate_import_flags.

     This function will convert the given PEM encoded CRL list to the
     native gnutls_x509_crl_t format.  The output will be stored in
     'crls' .  They will be automatically initialized.

     If the Certificate is PEM encoded it should have a header of "X509
     CRL".

     *Returns:* the number of certificates read or a negative error
     value.

     *Since:* 3.0

gnutls_x509_crl_print
---------------------

 -- Function: int gnutls_x509_crl_print (gnutls_x509_crl_t CRL,
          gnutls_certificate_print_formats_t FORMAT, gnutls_datum_t *
          OUT)
     CRL: The structure to be printed

     FORMAT: Indicate the format to use

     OUT: Newly allocated datum with null terminated string.

     This function will pretty print a X.509 certificate revocation
     list, suitable for display to a human.

     The output 'out' needs to be deallocated using 'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_set_authority_key_id
------------------------------------

 -- Function: int gnutls_x509_crl_set_authority_key_id
          (gnutls_x509_crl_t CRL, const void * ID, size_t ID_SIZE)
     CRL: a CRL of type 'gnutls_x509_crl_t'

     ID: The key ID

     ID_SIZE: Holds the size of the serial field.

     This function will set the CRL's authority key ID extension.  Only
     the keyIdentifier field can be set with this function.  This may be
     used by an authority that holds multiple private keys, to
     distinguish the used key.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crl_set_crt
-----------------------

 -- Function: int gnutls_x509_crl_set_crt (gnutls_x509_crl_t CRL,
          gnutls_x509_crt_t CRT, time_t REVOCATION_TIME)
     CRL: should contain a gnutls_x509_crl_t structure

     CRT: a certificate of type 'gnutls_x509_crt_t' with the revoked
     certificate

     REVOCATION_TIME: The time this certificate was revoked

     This function will set a revoked certificate's serial number to the
     CRL.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_set_crt_serial
------------------------------

 -- Function: int gnutls_x509_crl_set_crt_serial (gnutls_x509_crl_t CRL,
          const void * SERIAL, size_t SERIAL_SIZE, time_t
          REVOCATION_TIME)
     CRL: should contain a gnutls_x509_crl_t structure

     SERIAL: The revoked certificate's serial number

     SERIAL_SIZE: Holds the size of the serial field.

     REVOCATION_TIME: The time this certificate was revoked

     This function will set a revoked certificate's serial number to the
     CRL.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_set_next_update
-------------------------------

 -- Function: int gnutls_x509_crl_set_next_update (gnutls_x509_crl_t
          CRL, time_t EXP_TIME)
     CRL: should contain a gnutls_x509_crl_t structure

     EXP_TIME: The actual time

     This function will set the time this CRL will be updated.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_set_number
--------------------------

 -- Function: int gnutls_x509_crl_set_number (gnutls_x509_crl_t CRL,
          const void * NR, size_t NR_SIZE)
     CRL: a CRL of type 'gnutls_x509_crl_t'

     NR: The CRL number

     NR_SIZE: Holds the size of the nr field.

     This function will set the CRL's number extension.  This is to be
     used as a unique and monotonic number assigned to the CRL by the
     authority.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crl_set_this_update
-------------------------------

 -- Function: int gnutls_x509_crl_set_this_update (gnutls_x509_crl_t
          CRL, time_t ACT_TIME)
     CRL: should contain a gnutls_x509_crl_t structure

     ACT_TIME: The actual time

     This function will set the time this CRL was issued.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_set_version
---------------------------

 -- Function: int gnutls_x509_crl_set_version (gnutls_x509_crl_t CRL,
          unsigned int VERSION)
     CRL: should contain a gnutls_x509_crl_t structure

     VERSION: holds the version number.  For CRLv1 crls must be 1.

     This function will set the version of the CRL. This must be one for
     CRL version 1, and so on.  The CRLs generated by gnutls should have
     a version number of 2.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_sign2
---------------------

 -- Function: int gnutls_x509_crl_sign2 (gnutls_x509_crl_t CRL,
          gnutls_x509_crt_t ISSUER, gnutls_x509_privkey_t ISSUER_KEY,
          gnutls_digest_algorithm_t DIG, unsigned int FLAGS)
     CRL: should contain a gnutls_x509_crl_t structure

     ISSUER: is the certificate of the certificate issuer

     ISSUER_KEY: holds the issuer's private key

     DIG: The message digest to use.  GNUTLS_DIG_SHA1 is the safe choice
     unless you know what you're doing.

     FLAGS: must be 0

     This function will sign the CRL with the issuer's private key, and
     will copy the issuer's information into the CRL.

     This must be the last step in a certificate CRL since all the
     previously set parameters are now signed.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crl_verify
----------------------

 -- Function: int gnutls_x509_crl_verify (gnutls_x509_crl_t CRL, const
          gnutls_x509_crt_t * TRUSTED_CAS, int TCAS_SIZE, unsigned int
          FLAGS, unsigned int * VERIFY)
     CRL: is the crl to be verified

     TRUSTED_CAS: is a certificate list that is considered to be trusted
     one

     TCAS_SIZE: holds the number of CA certificates in CA_list

     FLAGS: Flags that may be used to change the verification algorithm.
     Use OR of the gnutls_certificate_verify_flags enumerations.

     VERIFY: will hold the crl verification output.

     This function will try to verify the given crl and return its
     verification status.  See 'gnutls_x509_crt_list_verify()' for a
     detailed description of return values.  Note that since GnuTLS
     3.1.4 this function includes the time checks.

     Note that value in 'verify' is set only when the return value of
     this function is success (i.e, failure to trust a CRL a certificate
     does not imply a negative return value).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_deinit
----------------------

 -- Function: void gnutls_x509_crq_deinit (gnutls_x509_crq_t CRQ)
     CRQ: The structure to be initialized

     This function will deinitialize a PKCS'10' certificate request
     structure.

gnutls_x509_crq_export
----------------------

 -- Function: int gnutls_x509_crq_export (gnutls_x509_crq_t CRQ,
          gnutls_x509_crt_fmt_t FORMAT, void * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     FORMAT: the format of output params.  One of PEM or DER.

     OUTPUT_DATA: will contain a certificate request PEM or DER encoded

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will export the certificate request to a PEM or DER
     encoded PKCS10 structure.

     If the buffer provided is not long enough to hold the output, then
     'GNUTLS_E_SHORT_MEMORY_BUFFER' will be returned and *
     'output_data_size' will be updated.

     If the structure is PEM encoded, it will have a header of "BEGIN
     NEW CERTIFICATE REQUEST".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_export2
-----------------------

 -- Function: int gnutls_x509_crq_export2 (gnutls_x509_crq_t CRQ,
          gnutls_x509_crt_fmt_t FORMAT, gnutls_datum_t * OUT)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     FORMAT: the format of output params.  One of PEM or DER.

     OUT: will contain a certificate request PEM or DER encoded

     This function will export the certificate request to a PEM or DER
     encoded PKCS10 structure.

     The output buffer is allocated using 'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN
     NEW CERTIFICATE REQUEST".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     Since 3.1.3

gnutls_x509_crq_get_attribute_by_oid
------------------------------------

 -- Function: int gnutls_x509_crq_get_attribute_by_oid
          (gnutls_x509_crq_t CRQ, const char * OID, int INDX, void *
          BUF, size_t * BUF_SIZE)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     OID: holds an Object Identifier in null-terminated string

     INDX: In case multiple same OIDs exist in the attribute list, this
     specifies which to get, use (0) to get the first one

     BUF: a pointer to a structure to hold the attribute data (may be
     'NULL' )

     BUF_SIZE: initially holds the size of 'buf'

     This function will return the attribute in the certificate request
     specified by the given Object ID. The attribute will be DER
     encoded.

     Attributes in a certificate request is an optional set of data
     appended to the request.  Their interpretation depends on the CA
     policy.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_get_attribute_data
----------------------------------

 -- Function: int gnutls_x509_crq_get_attribute_data (gnutls_x509_crq_t
          CRQ, int INDX, void * DATA, size_t * SIZEOF_DATA)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     INDX: Specifies which attribute number to get.  Use (0) to get the
     first one.

     DATA: a pointer to a structure to hold the data (may be null)

     SIZEOF_DATA: initially holds the size of 'oid'

     This function will return the requested attribute data in the
     certificate request.  The attribute data will be stored as a string
     in the provided buffer.

     Use 'gnutls_x509_crq_get_attribute_info()' to extract the OID. Use
     'gnutls_x509_crq_get_attribute_by_oid()' instead, if you want to
     get data indexed by the attribute OID rather than sequence.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If your have
     reached the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_attribute_info
----------------------------------

 -- Function: int gnutls_x509_crq_get_attribute_info (gnutls_x509_crq_t
          CRQ, int INDX, void * OID, size_t * SIZEOF_OID)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     INDX: Specifies which attribute number to get.  Use (0) to get the
     first one.

     OID: a pointer to a structure to hold the OID

     SIZEOF_OID: initially holds the maximum size of 'oid' , on return
     holds actual size of 'oid' .

     This function will return the requested attribute OID in the
     certificate, and the critical flag for it.  The attribute OID will
     be stored as a string in the provided buffer.  Use
     'gnutls_x509_crq_get_attribute_data()' to extract the data.

     If the buffer provided is not long enough to hold the output, then
     * 'sizeof_oid' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER' will
     be returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If your have
     reached the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_basic_constraints
-------------------------------------

 -- Function: int gnutls_x509_crq_get_basic_constraints
          (gnutls_x509_crq_t CRQ, unsigned int * CRITICAL, unsigned int
          * CA, int * PATHLEN)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     CRITICAL: will be non-zero if the extension is marked as critical

     CA: pointer to output integer indicating CA status, may be NULL,
     value is 1 if the certificate CA flag is set, 0 otherwise.

     PATHLEN: pointer to output integer indicating path length (may be
     NULL), non-negative error codes indicate a present
     pathLenConstraint field and the actual value, -1 indicate that the
     field is absent.

     This function will read the certificate's basic constraints, and
     return the certificates CA status.  It reads the basicConstraints
     X.509 extension (2.5.29.19).

     *Returns:* If the certificate is a CA a positive value will be
     returned, or (0) if the certificate does not have CA flag set.  A
     negative error code may be returned in case of errors.  If the
     certificate does not contain the basicConstraints extension
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_challenge_password
--------------------------------------

 -- Function: int gnutls_x509_crq_get_challenge_password
          (gnutls_x509_crq_t CRQ, char * PASS, size_t * PASS_SIZE)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     PASS: will hold a (0)-terminated password string

     PASS_SIZE: Initially holds the size of 'pass' .

     This function will return the challenge password in the request.
     The challenge password is intended to be used for requesting a
     revocation of the certificate.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_get_dn
----------------------

 -- Function: int gnutls_x509_crq_get_dn (gnutls_x509_crq_t CRQ, char *
          BUF, size_t * BUF_SIZE)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     BUF: a pointer to a structure to hold the name (may be 'NULL' )

     BUF_SIZE: initially holds the size of 'buf'

     This function will copy the name of the Certificate request subject
     to the provided buffer.  The name will be in the form
     "C=xxxx,O=yyyy,CN=zzzz" as described in RFC 2253.  The output
     string 'buf' will be ASCII or UTF-8 encoded, depending on the
     certificate data.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the * 'buf_size' will be updated
     with the required size.  On success 0 is returned.

gnutls_x509_crq_get_dn2
-----------------------

 -- Function: int gnutls_x509_crq_get_dn2 (gnutls_x509_crq_t CRQ,
          gnutls_datum_t * DN)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     DN: a pointer to a structure to hold the name

     This function will allocate buffer and copy the name of the
     Certificate request.  The name will be in the form
     "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514.  The output string
     will be ASCII or UTF-8 encoded, depending on the certificate data.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  and a negative error code on
     error.

     *Since:* 3.1.10

gnutls_x509_crq_get_dn_by_oid
-----------------------------

 -- Function: int gnutls_x509_crq_get_dn_by_oid (gnutls_x509_crq_t CRQ,
          const char * OID, int INDX, unsigned int RAW_FLAG, void * BUF,
          size_t * BUF_SIZE)
     CRQ: should contain a gnutls_x509_crq_t structure

     OID: holds an Object Identifier in a null terminated string

     INDX: In case multiple same OIDs exist in the RDN, this specifies
     which to get.  Use (0) to get the first one.

     RAW_FLAG: If non-zero returns the raw DER data of the DN part.

     BUF: a pointer to a structure to hold the name (may be 'NULL' )

     BUF_SIZE: initially holds the size of 'buf'

     This function will extract the part of the name of the Certificate
     request subject, specified by the given OID. The output will be
     encoded as described in RFC2253.  The output string will be ASCII
     or UTF-8 encoded, depending on the certificate data.

     Some helper macros with popular OIDs can be found in gnutls/x509.h
     If raw flag is (0), this function will only return known OIDs as
     text.  Other OIDs will be DER encoded, as described in RFC2253 - in
     hex format with a '\#' prefix.  You can check about known OIDs
     using 'gnutls_x509_dn_oid_known()' .

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the * 'buf_size' will be updated
     with the required size.  On success 0 is returned.

gnutls_x509_crq_get_dn_oid
--------------------------

 -- Function: int gnutls_x509_crq_get_dn_oid (gnutls_x509_crq_t CRQ, int
          INDX, void * OID, size_t * SIZEOF_OID)
     CRQ: should contain a gnutls_x509_crq_t structure

     INDX: Specifies which DN OID to get.  Use (0) to get the first one.

     OID: a pointer to a structure to hold the name (may be 'NULL' )

     SIZEOF_OID: initially holds the size of 'oid'

     This function will extract the requested OID of the name of the
     certificate request subject, specified by the given index.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the * 'sizeof_oid' will be
     updated with the required size.  On success 0 is returned.

gnutls_x509_crq_get_extension_by_oid
------------------------------------

 -- Function: int gnutls_x509_crq_get_extension_by_oid
          (gnutls_x509_crq_t CRQ, const char * OID, int INDX, void *
          BUF, size_t * BUF_SIZE, unsigned int * CRITICAL)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     OID: holds an Object Identifier in a null terminated string

     INDX: In case multiple same OIDs exist in the extensions, this
     specifies which to get.  Use (0) to get the first one.

     BUF: a pointer to a structure to hold the name (may be null)

     BUF_SIZE: initially holds the size of 'buf'

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will return the extension specified by the OID in the
     certificate.  The extensions will be returned as binary data DER
     encoded, in the provided buffer.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If the
     certificate does not contain the specified extension
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_extension_by_oid2
-------------------------------------

 -- Function: int gnutls_x509_crq_get_extension_by_oid2
          (gnutls_x509_crq_t CRQ, const char * OID, int INDX,
          gnutls_datum_t * OUTPUT, unsigned int * CRITICAL)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     OID: holds an Object Identifier in a null terminated string

     INDX: In case multiple same OIDs exist in the extensions, this
     specifies which to get.  Use (0) to get the first one.

     OUTPUT: will hold the allocated extension data

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will return the extension specified by the OID in the
     certificate.  The extensions will be returned as binary data DER
     encoded, in the provided buffer.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If the
     certificate does not contain the specified extension
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 3.3.8

gnutls_x509_crq_get_extension_data
----------------------------------

 -- Function: int gnutls_x509_crq_get_extension_data (gnutls_x509_crq_t
          CRQ, int INDX, void * DATA, size_t * SIZEOF_DATA)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     INDX: Specifies which extension number to get.  Use (0) to get the
     first one.

     DATA: a pointer to a structure to hold the data (may be null)

     SIZEOF_DATA: initially holds the size of 'oid'

     This function will return the requested extension data in the
     certificate.  The extension data will be stored as a string in the
     provided buffer.

     Use 'gnutls_x509_crq_get_extension_info()' to extract the OID and
     critical flag.  Use 'gnutls_x509_crq_get_extension_by_oid()'
     instead, if you want to get data indexed by the extension OID
     rather than sequence.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If your have
     reached the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_extension_data2
-----------------------------------

 -- Function: int gnutls_x509_crq_get_extension_data2 (gnutls_x509_crq_t
          CRQ, unsigned INDX, gnutls_datum_t * DATA)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     INDX: Specifies which extension OID to read.  Use (0) to get the
     first one.

     DATA: will contain the extension DER-encoded data

     This function will return the requested extension data in the
     certificate request.  The extension data will be allocated using
     'gnutls_malloc()' .

     Use 'gnutls_x509_crq_get_extension_info()' to extract the OID.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If you have reached
     the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 3.3.0

gnutls_x509_crq_get_extension_info
----------------------------------

 -- Function: int gnutls_x509_crq_get_extension_info (gnutls_x509_crq_t
          CRQ, int INDX, void * OID, size_t * SIZEOF_OID, unsigned int *
          CRITICAL)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     INDX: Specifies which extension number to get.  Use (0) to get the
     first one.

     OID: a pointer to a structure to hold the OID

     SIZEOF_OID: initially holds the maximum size of 'oid' , on return
     holds actual size of 'oid' .

     CRITICAL: output variable with critical flag, may be NULL.

     This function will return the requested extension OID in the
     certificate, and the critical flag for it.  The extension OID will
     be stored as a string in the provided buffer.  Use
     'gnutls_x509_crq_get_extension_data()' to extract the data.

     If the buffer provided is not long enough to hold the output, then
     * 'sizeof_oid' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER' will
     be returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code in case of an error.  If your have
     reached the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_key_id
--------------------------

 -- Function: int gnutls_x509_crq_get_key_id (gnutls_x509_crq_t CRQ,
          unsigned int FLAGS, unsigned char * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     CRQ: a certificate of type 'gnutls_x509_crq_t'

     FLAGS: should be 0 for now

     OUTPUT_DATA: will contain the key ID

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will return a unique ID that depends on the public
     key parameters.  This ID can be used in checking whether a
     certificate corresponds to the given private key.

     If the buffer provided is not long enough to hold the output, then
     * 'output_data_size' is updated and GNUTLS_E_SHORT_MEMORY_BUFFER
     will be returned.  The output will normally be a SHA-1 hash output,
     which is 20 bytes.

     *Returns:* In case of failure a negative error code will be
     returned, and 0 on success.

     *Since:* 2.8.0

gnutls_x509_crq_get_key_purpose_oid
-----------------------------------

 -- Function: int gnutls_x509_crq_get_key_purpose_oid (gnutls_x509_crq_t
          CRQ, int INDX, void * OID, size_t * SIZEOF_OID, unsigned int *
          CRITICAL)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     INDX: This specifies which OID to return, use (0) to get the first
     one

     OID: a pointer to a buffer to hold the OID (may be 'NULL' )

     SIZEOF_OID: initially holds the size of 'oid'

     CRITICAL: output variable with critical flag, may be 'NULL' .

     This function will extract the key purpose OIDs of the Certificate
     specified by the given index.  These are stored in the Extended Key
     Usage extension (2.5.29.37).  See the GNUTLS_KP_* definitions for
     human readable names.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the * 'sizeof_oid' will be
     updated with the required size.  On success 0 is returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_key_rsa_raw
-------------------------------

 -- Function: int gnutls_x509_crq_get_key_rsa_raw (gnutls_x509_crq_t
          CRQ, gnutls_datum_t * M, gnutls_datum_t * E)
     CRQ: Holds the certificate

     M: will hold the modulus

     E: will hold the public exponent

     This function will export the RSA public key's parameters found in
     the given structure.  The new parameters will be allocated using
     'gnutls_malloc()' and will be stored in the appropriate datum.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crq_get_key_usage
-----------------------------

 -- Function: int gnutls_x509_crq_get_key_usage (gnutls_x509_crq_t CRQ,
          unsigned int * KEY_USAGE, unsigned int * CRITICAL)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     KEY_USAGE: where the key usage bits will be stored

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will return certificate's key usage, by reading the
     keyUsage X.509 extension (2.5.29.15).  The key usage value will
     ORed values of the: 'GNUTLS_KEY_DIGITAL_SIGNATURE' ,
     'GNUTLS_KEY_NON_REPUDIATION' , 'GNUTLS_KEY_KEY_ENCIPHERMENT' ,
     'GNUTLS_KEY_DATA_ENCIPHERMENT' , 'GNUTLS_KEY_KEY_AGREEMENT' ,
     'GNUTLS_KEY_KEY_CERT_SIGN' , 'GNUTLS_KEY_CRL_SIGN' ,
     'GNUTLS_KEY_ENCIPHER_ONLY' , 'GNUTLS_KEY_DECIPHER_ONLY' .

     *Returns:* the certificate key usage, or a negative error code in
     case of parsing error.  If the certificate does not contain the
     keyUsage extension 'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be
     returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_pk_algorithm
--------------------------------

 -- Function: int gnutls_x509_crq_get_pk_algorithm (gnutls_x509_crq_t
          CRQ, unsigned int * BITS)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     BITS: if bits is non-'NULL' it will hold the size of the
     parameters' in bits

     This function will return the public key algorithm of a PKCS'10'
     certificate request.

     If bits is non-'NULL' , it should have enough size to hold the
     parameters size in bits.  For RSA the bits returned is the modulus.
     For DSA the bits returned are of the public exponent.

     *Returns:* a member of the 'gnutls_pk_algorithm_t' enumeration on
     success, or a negative error code on error.

gnutls_x509_crq_get_private_key_usage_period
--------------------------------------------

 -- Function: int gnutls_x509_crq_get_private_key_usage_period
          (gnutls_x509_crq_t CRQ, time_t * ACTIVATION, time_t *
          EXPIRATION, unsigned int * CRITICAL)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     ACTIVATION: The activation time

     EXPIRATION: The expiration time

     CRITICAL: the extension status

     This function will return the expiration and activation times of
     the private key of the certificate.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

gnutls_x509_crq_get_subject_alt_name
------------------------------------

 -- Function: int gnutls_x509_crq_get_subject_alt_name
          (gnutls_x509_crq_t CRQ, unsigned int SEQ, void * RET, size_t *
          RET_SIZE, unsigned int * RET_TYPE, unsigned int * CRITICAL)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     SEQ: specifies the sequence number of the alt name, 0 for the first
     one, 1 for the second etc.

     RET: is the place where the alternative name will be copied to

     RET_SIZE: holds the size of ret.

     RET_TYPE: holds the 'gnutls_x509_subject_alt_name_t' name type

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the alternative names, contained in the
     given certificate.  It is the same as
     'gnutls_x509_crq_get_subject_alt_name()' except for the fact that
     it will return the type of the alternative name in 'ret_type' even
     if the function fails for some reason (i.e.  the buffer provided is
     not enough).

     *Returns:* the alternative subject name type on success, one of the
     enumerated 'gnutls_x509_subject_alt_name_t' .  It will return
     'GNUTLS_E_SHORT_MEMORY_BUFFER' if 'ret_size' is not large enough to
     hold the value.  In that case 'ret_size' will be updated with the
     required size.  If the certificate request does not have an
     Alternative name with the specified sequence number then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_subject_alt_othername_oid
---------------------------------------------

 -- Function: int gnutls_x509_crq_get_subject_alt_othername_oid
          (gnutls_x509_crq_t CRQ, unsigned int SEQ, void * RET, size_t *
          RET_SIZE)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     RET: is the place where the otherName OID will be copied to

     RET_SIZE: holds the size of ret.

     This function will extract the type OID of an otherName Subject
     Alternative Name, contained in the given certificate, and return
     the type as an enumerated element.

     This function is only useful if
     'gnutls_x509_crq_get_subject_alt_name()' returned
     'GNUTLS_SAN_OTHERNAME' .

     *Returns:* the alternative subject name type on success, one of the
     enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
     will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types, e.g.
     'GNUTLS_SAN_OTHERNAME_XMPP' , and 'GNUTLS_SAN_OTHERNAME' for
     unknown OIDs.  It will return 'GNUTLS_E_SHORT_MEMORY_BUFFER' if
     'ret_size' is not large enough to hold the value.  In that case
     'ret_size' will be updated with the required size.  If the
     certificate does not have an Alternative name with the specified
     sequence number and with the otherName type then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Since:* 2.8.0

gnutls_x509_crq_get_version
---------------------------

 -- Function: int gnutls_x509_crq_get_version (gnutls_x509_crq_t CRQ)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     This function will return the version of the specified Certificate
     request.

     *Returns:* version of certificate request, or a negative error code
     on error.

gnutls_x509_crq_import
----------------------

 -- Function: int gnutls_x509_crq_import (gnutls_x509_crq_t CRQ, const
          gnutls_datum_t * DATA, gnutls_x509_crt_fmt_t FORMAT)
     CRQ: The structure to store the parsed certificate request.

     DATA: The DER or PEM encoded certificate.

     FORMAT: One of DER or PEM

     This function will convert the given DER or PEM encoded certificate
     request to a 'gnutls_x509_crq_t' structure.  The output will be
     stored in 'crq' .

     If the Certificate is PEM encoded it should have a header of "NEW
     CERTIFICATE REQUEST".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_init
--------------------

 -- Function: int gnutls_x509_crq_init (gnutls_x509_crq_t * CRQ)
     CRQ: The structure to be initialized

     This function will initialize a PKCS'10' certificate request
     structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_print
---------------------

 -- Function: int gnutls_x509_crq_print (gnutls_x509_crq_t CRQ,
          gnutls_certificate_print_formats_t FORMAT, gnutls_datum_t *
          OUT)
     CRQ: The structure to be printed

     FORMAT: Indicate the format to use

     OUT: Newly allocated datum with null terminated string.

     This function will pretty print a certificate request, suitable for
     display to a human.

     The output 'out' needs to be deallocated using 'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crq_set_attribute_by_oid
------------------------------------

 -- Function: int gnutls_x509_crq_set_attribute_by_oid
          (gnutls_x509_crq_t CRQ, const char * OID, void * BUF, size_t
          BUF_SIZE)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     OID: holds an Object Identifier in a null-terminated string

     BUF: a pointer to a structure that holds the attribute data

     BUF_SIZE: holds the size of 'buf'

     This function will set the attribute in the certificate request
     specified by the given Object ID. The provided attribute must be be
     DER encoded.

     Attributes in a certificate request is an optional set of data
     appended to the request.  Their interpretation depends on the CA
     policy.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_set_basic_constraints
-------------------------------------

 -- Function: int gnutls_x509_crq_set_basic_constraints
          (gnutls_x509_crq_t CRQ, unsigned int CA, int
          PATHLENCONSTRAINT)
     CRQ: a certificate request of type 'gnutls_x509_crq_t'

     CA: true(1) or false(0) depending on the Certificate authority
     status.

     PATHLENCONSTRAINT: non-negative error codes indicate maximum length
     of path, and negative error codes indicate that the
     pathLenConstraints field should not be present.

     This function will set the basicConstraints certificate extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crq_set_challenge_password
--------------------------------------

 -- Function: int gnutls_x509_crq_set_challenge_password
          (gnutls_x509_crq_t CRQ, const char * PASS)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     PASS: holds a (0)-terminated password

     This function will set a challenge password to be used when
     revoking the request.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_set_dn
----------------------

 -- Function: int gnutls_x509_crq_set_dn (gnutls_x509_crq_t CRQ, const
          char * DN, const char ** ERR)
     CRQ: a certificate of type 'gnutls_x509_crq_t'

     DN: a comma separated DN string (RFC4514)

     ERR: indicates the error position (if any)

     This function will set the DN on the provided certificate.  The
     input string should be plain ASCII or UTF-8 encoded.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_set_dn_by_oid
-----------------------------

 -- Function: int gnutls_x509_crq_set_dn_by_oid (gnutls_x509_crq_t CRQ,
          const char * OID, unsigned int RAW_FLAG, const void * DATA,
          unsigned int SIZEOF_DATA)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     OID: holds an Object Identifier in a (0)-terminated string

     RAW_FLAG: must be 0, or 1 if the data are DER encoded

     DATA: a pointer to the input data

     SIZEOF_DATA: holds the size of 'data'

     This function will set the part of the name of the Certificate
     request subject, specified by the given OID. The input string
     should be ASCII or UTF-8 encoded.

     Some helper macros with popular OIDs can be found in gnutls/x509.h
     With this function you can only set the known OIDs.  You can test
     for known OIDs using 'gnutls_x509_dn_oid_known()' .  For OIDs that
     are not known (by gnutls) you should properly DER encode your data,
     and call this function with raw_flag set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_set_key
-----------------------

 -- Function: int gnutls_x509_crq_set_key (gnutls_x509_crq_t CRQ,
          gnutls_x509_privkey_t KEY)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     KEY: holds a private key

     This function will set the public parameters from the given private
     key to the request.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_set_key_purpose_oid
-----------------------------------

 -- Function: int gnutls_x509_crq_set_key_purpose_oid (gnutls_x509_crq_t
          CRQ, const void * OID, unsigned int CRITICAL)
     CRQ: a certificate of type 'gnutls_x509_crq_t'

     OID: a pointer to a (0)-terminated string that holds the OID

     CRITICAL: Whether this extension will be critical or not

     This function will set the key purpose OIDs of the Certificate.
     These are stored in the Extended Key Usage extension (2.5.29.37)
     See the GNUTLS_KP_* definitions for human readable names.

     Subsequent calls to this function will append OIDs to the OID list.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crq_set_key_rsa_raw
-------------------------------

 -- Function: int gnutls_x509_crq_set_key_rsa_raw (gnutls_x509_crq_t
          CRQ, const gnutls_datum_t * M, const gnutls_datum_t * E)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     M: holds the modulus

     E: holds the public exponent

     This function will set the public parameters from the given private
     key to the request.  Only RSA keys are currently supported.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.6.0

gnutls_x509_crq_set_key_usage
-----------------------------

 -- Function: int gnutls_x509_crq_set_key_usage (gnutls_x509_crq_t CRQ,
          unsigned int USAGE)
     CRQ: a certificate request of type 'gnutls_x509_crq_t'

     USAGE: an ORed sequence of the GNUTLS_KEY_* elements.

     This function will set the keyUsage certificate extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crq_set_private_key_usage_period
--------------------------------------------

 -- Function: int gnutls_x509_crq_set_private_key_usage_period
          (gnutls_x509_crq_t CRQ, time_t ACTIVATION, time_t EXPIRATION)
     CRQ: a certificate of type 'gnutls_x509_crq_t'

     ACTIVATION: The activation time

     EXPIRATION: The expiration time

     This function will set the private key usage period extension
     (2.5.29.16).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_set_subject_alt_name
------------------------------------

 -- Function: int gnutls_x509_crq_set_subject_alt_name
          (gnutls_x509_crq_t CRQ, gnutls_x509_subject_alt_name_t NT,
          const void * DATA, unsigned int DATA_SIZE, unsigned int FLAGS)
     CRQ: a certificate request of type 'gnutls_x509_crq_t'

     NT: is one of the 'gnutls_x509_subject_alt_name_t' enumerations

     DATA: The data to be set

     DATA_SIZE: The size of data to be set

     FLAGS: 'GNUTLS_FSAN_SET' to clear previous data or
     'GNUTLS_FSAN_APPEND' to append.

     This function will set the subject alternative name certificate
     extension.  It can set the following types:

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crq_set_version
---------------------------

 -- Function: int gnutls_x509_crq_set_version (gnutls_x509_crq_t CRQ,
          unsigned int VERSION)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     VERSION: holds the version number, for v1 Requests must be 1

     This function will set the version of the certificate request.  For
     version 1 requests this must be one.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crq_sign2
---------------------

 -- Function: int gnutls_x509_crq_sign2 (gnutls_x509_crq_t CRQ,
          gnutls_x509_privkey_t KEY, gnutls_digest_algorithm_t DIG,
          unsigned int FLAGS)
     CRQ: should contain a 'gnutls_x509_crq_t' structure

     KEY: holds a private key

     DIG: The message digest to use, i.e., 'GNUTLS_DIG_SHA1'

     FLAGS: must be 0

     This function will sign the certificate request with a private key.
     This must be the same key as the one used in
     'gnutls_x509_crt_set_key()' since a certificate request is self
     signed.

     This must be the last step in a certificate request generation
     since all the previously set parameters are now signed.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.  'GNUTLS_E_ASN1_VALUE_NOT_FOUND' is returned if you
     didn't set all information in the certificate request (e.g., the
     version using 'gnutls_x509_crq_set_version()' ).

gnutls_x509_crq_verify
----------------------

 -- Function: int gnutls_x509_crq_verify (gnutls_x509_crq_t CRQ,
          unsigned int FLAGS)
     CRQ: is the crq to be verified

     FLAGS: Flags that may be used to change the verification algorithm.
     Use OR of the gnutls_certificate_verify_flags enumerations.

     This function will verify self signature in the certificate request
     and return its status.

     *Returns:* In case of a verification failure
     'GNUTLS_E_PK_SIG_VERIFY_FAILED' is returned, and zero or positive
     code on success.

     Since 2.12.0

gnutls_x509_crt_check_hostname
------------------------------

 -- Function: int gnutls_x509_crt_check_hostname (gnutls_x509_crt_t
          CERT, const char * HOSTNAME)
     CERT: should contain an gnutls_x509_crt_t structure

     HOSTNAME: A null terminated string that contains a DNS name

     This function will check if the given certificate's subject matches
     the given hostname.  This is a basic implementation of the matching
     described in RFC6125, and takes into account wildcards, and the
     DNSName/IPAddress subject alternative name PKIX extension.

     For details see also 'gnutls_x509_crt_check_hostname2()' .

     *Returns:* non-zero for a successful match, and zero on failure.

gnutls_x509_crt_check_hostname2
-------------------------------

 -- Function: int gnutls_x509_crt_check_hostname2 (gnutls_x509_crt_t
          CERT, const char * HOSTNAME, unsigned int FLAGS)
     CERT: should contain an gnutls_x509_crt_t structure

     HOSTNAME: A null terminated string that contains a DNS name

     FLAGS: gnutls_certificate_verify_flags

     This function will check if the given certificate's subject matches
     the given hostname.  This is a basic implementation of the matching
     described in RFC6125, and takes into account wildcards, and the
     DNSName/IPAddress subject alternative name PKIX extension.

     IPv4 addresses are accepted by this function in the dotted-decimal
     format (e.g, ddd.ddd.ddd.ddd), and IPv6 addresses in the
     hexadecimal x:x:x:x:x:x:x:x format.  For them the IPAddress subject
     alternative name extension is consulted, as well as the DNSNames in
     case of a non-match.  The latter fallback exists due to
     misconfiguration of many servers which place an IPAddress inside
     the DNSName extension.

     The comparison of dns names may have false-negatives as it is done
     byte by byte in non-ascii names.

     When the flag 'GNUTLS_VERIFY_DO_NOT_ALLOW_WILDCARDS' is specified
     no wildcards are considered.  Otherwise they are only considered if
     the domain name consists of three components or more, and the
     wildcard starts at the leftmost position.

     *Returns:* non-zero for a successful match, and zero on failure.

gnutls_x509_crt_check_issuer
----------------------------

 -- Function: int gnutls_x509_crt_check_issuer (gnutls_x509_crt_t CERT,
          gnutls_x509_crt_t ISSUER)
     CERT: is the certificate to be checked

     ISSUER: is the certificate of a possible issuer

     This function will check if the given certificate was issued by the
     given issuer.  It checks the DN fields and the authority key
     identifier and subject key identifier fields match.

     If the same certificate is provided at the 'cert' and 'issuer'
     fields, it will check whether the certificate is self-signed.

     *Returns:* It will return true (1) if the given certificate is
     issued by the given issuer, and false (0) if not.

gnutls_x509_crt_check_revocation
--------------------------------

 -- Function: int gnutls_x509_crt_check_revocation (gnutls_x509_crt_t
          CERT, const gnutls_x509_crl_t * CRL_LIST, int CRL_LIST_LENGTH)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     CRL_LIST: should contain a list of gnutls_x509_crl_t structures

     CRL_LIST_LENGTH: the length of the crl_list

     This function will return check if the given certificate is
     revoked.  It is assumed that the CRLs have been verified before.

     *Returns:* 0 if the certificate is NOT revoked, and 1 if it is.  A
     negative error code is returned on error.

gnutls_x509_crt_cpy_crl_dist_points
-----------------------------------

 -- Function: int gnutls_x509_crt_cpy_crl_dist_points (gnutls_x509_crt_t
          DST, gnutls_x509_crt_t SRC)
     DST: a certificate of type 'gnutls_x509_crt_t'

     SRC: the certificate where the dist points will be copied from

     This function will copy the CRL distribution points certificate
     extension, from the source to the destination certificate.  This
     may be useful to copy from a CA certificate to issued ones.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_deinit
----------------------

 -- Function: void gnutls_x509_crt_deinit (gnutls_x509_crt_t CERT)
     CERT: The structure to be deinitialized

     This function will deinitialize a certificate structure.

gnutls_x509_crt_export
----------------------

 -- Function: int gnutls_x509_crt_export (gnutls_x509_crt_t CERT,
          gnutls_x509_crt_fmt_t FORMAT, void * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     CERT: Holds the certificate

     FORMAT: the format of output params.  One of PEM or DER.

     OUTPUT_DATA: will contain a certificate PEM or DER encoded

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will export the certificate to DER or PEM format.

     If the buffer provided is not long enough to hold the output, then
     *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
     be returned.

     If the structure is PEM encoded, it will have a header of "BEGIN
     CERTIFICATE".

     *Returns:* In case of failure a negative error code will be
     returned, and 0 on success.

gnutls_x509_crt_export2
-----------------------

 -- Function: int gnutls_x509_crt_export2 (gnutls_x509_crt_t CERT,
          gnutls_x509_crt_fmt_t FORMAT, gnutls_datum_t * OUT)
     CERT: Holds the certificate

     FORMAT: the format of output params.  One of PEM or DER.

     OUT: will contain a certificate PEM or DER encoded

     This function will export the certificate to DER or PEM format.
     The output buffer is allocated using 'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN
     CERTIFICATE".

     *Returns:* In case of failure a negative error code will be
     returned, and 0 on success.

     *Since:* 3.1.3

gnutls_x509_crt_get_activation_time
-----------------------------------

 -- Function: time_t gnutls_x509_crt_get_activation_time
          (gnutls_x509_crt_t CERT)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     This function will return the time this Certificate was or will be
     activated.

     *Returns:* activation time, or (time_t)-1 on error.

gnutls_x509_crt_get_authority_info_access
-----------------------------------------

 -- Function: int gnutls_x509_crt_get_authority_info_access
          (gnutls_x509_crt_t CRT, unsigned int SEQ, int WHAT,
          gnutls_datum_t * DATA, unsigned int * CRITICAL)
     CRT: Holds the certificate

     SEQ: specifies the sequence number of the access descriptor (0 for
     the first one, 1 for the second etc.)

     WHAT: what data to get, a 'gnutls_info_access_what_t' type.

     DATA: output data to be freed with 'gnutls_free()' .

     CRITICAL: pointer to output integer that is set to non-zero if the
     extension is marked as critical (may be 'NULL' )

     Note that a simpler API to access the authority info data is
     provided by 'gnutls_x509_aia_get()' and
     'gnutls_x509_ext_import_aia()' .

     This function extracts the Authority Information Access (AIA)
     extension, see RFC 5280 section 4.2.2.1 for more information.  The
     AIA extension holds a sequence of AccessDescription (AD) data.

     The 'seq' input parameter is used to indicate which member of the
     sequence the caller is interested in.  The first member is 0, the
     second member 1 and so on.  When the 'seq' value is out of bounds,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     The type of data returned in 'data' is specified via 'what' which
     should be 'gnutls_info_access_what_t' values.

     If 'what' is 'GNUTLS_IA_ACCESSMETHOD_OID' then 'data' will hold the
     accessMethod OID (e.g., "1.3.6.1.5.5.7.48.1").

     If 'what' is 'GNUTLS_IA_ACCESSLOCATION_GENERALNAME_TYPE' , 'data'
     will hold the accessLocation GeneralName type (e.g.,
     "uniformResourceIdentifier").

     If 'what' is 'GNUTLS_IA_URI' , 'data' will hold the accessLocation
     URI data.  Requesting this 'what' value leads to an error if the
     accessLocation is not of the "uniformResourceIdentifier" type.

     If 'what' is 'GNUTLS_IA_OCSP_URI' , 'data' will hold the OCSP URI.
     Requesting this 'what' value leads to an error if the accessMethod
     is not 1.3.6.1.5.5.7.48.1 aka OSCP, or if accessLocation is not of
     the "uniformResourceIdentifier" type.  In that case
     'GNUTLS_E_UNKNOWN_ALGORITHM' will be returned, and 'seq' should be
     increased and this function called again.

     If 'what' is 'GNUTLS_IA_CAISSUERS_URI' , 'data' will hold the
     caIssuers URI. Requesting this 'what' value leads to an error if
     the accessMethod is not 1.3.6.1.5.5.7.48.2 aka caIssuers, or if
     accessLocation is not of the "uniformResourceIdentifier" type.  In
     that case handle as in 'GNUTLS_IA_OCSP_URI' .

     More 'what' values may be allocated in the future as needed.

     If 'data' is NULL, the function does the same without storing the
     output data, that is, it will set 'critical' and do error checking
     as usual.

     The value of the critical flag is returned in * 'critical' .
     Supply a NULL 'critical' if you want the function to make sure the
     extension is non-critical, as required by RFC 5280.

     *Returns:* 'GNUTLS_E_SUCCESS' on success,
     'GNUTLS_E_INVALID_REQUEST' on invalid 'crt' ,
     'GNUTLS_E_CONSTRAINT_ERROR' if the extension is incorrectly marked
     as critical (use a non-NULL 'critical' to override),
     'GNUTLS_E_UNKNOWN_ALGORITHM' if the requested OID does not match
     (e.g., when using 'GNUTLS_IA_OCSP_URI' ), otherwise a negative
     error code.

     *Since:* 3.0

gnutls_x509_crt_get_authority_key_gn_serial
-------------------------------------------

 -- Function: int gnutls_x509_crt_get_authority_key_gn_serial
          (gnutls_x509_crt_t CERT, unsigned int SEQ, void * ALT, size_t
          * ALT_SIZE, unsigned int * ALT_TYPE, void * SERIAL, size_t *
          SERIAL_SIZE, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     ALT: is the place where the alternative name will be copied to

     ALT_SIZE: holds the size of alt.

     ALT_TYPE: holds the type of the alternative name (one of
     gnutls_x509_subject_alt_name_t).

     SERIAL: buffer to store the serial number (may be null)

     SERIAL_SIZE: Holds the size of the serial field (may be null)

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the X.509 authority key identifier when
     stored as a general name (authorityCertIssuer) and serial number.

     Because more than one general names might be stored 'seq' can be
     used as a counter to request them all until
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.0

gnutls_x509_crt_get_authority_key_id
------------------------------------

 -- Function: int gnutls_x509_crt_get_authority_key_id
          (gnutls_x509_crt_t CERT, void * ID, size_t * ID_SIZE, unsigned
          int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     ID: The place where the identifier will be copied

     ID_SIZE: Holds the size of the id field.

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the X.509v3 certificate authority's key
     identifier.  This is obtained by the X.509 Authority Key identifier
     extension field (2.5.29.35).  Note that this function only returns
     the keyIdentifier field of the extension and
     'GNUTLS_E_X509_UNSUPPORTED_EXTENSION' , if the extension contains
     the name and serial number of the certificate.  In that case
     'gnutls_x509_crt_get_authority_key_gn_serial()' may be used.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

gnutls_x509_crt_get_basic_constraints
-------------------------------------

 -- Function: int gnutls_x509_crt_get_basic_constraints
          (gnutls_x509_crt_t CERT, unsigned int * CRITICAL, unsigned int
          * CA, int * PATHLEN)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     CRITICAL: will be non-zero if the extension is marked as critical

     CA: pointer to output integer indicating CA status, may be NULL,
     value is 1 if the certificate CA flag is set, 0 otherwise.

     PATHLEN: pointer to output integer indicating path length (may be
     NULL), non-negative error codes indicate a present
     pathLenConstraint field and the actual value, -1 indicate that the
     field is absent.

     This function will read the certificate's basic constraints, and
     return the certificates CA status.  It reads the basicConstraints
     X.509 extension (2.5.29.19).

     *Returns:* If the certificate is a CA a positive value will be
     returned, or (0) if the certificate does not have CA flag set.  A
     negative error code may be returned in case of errors.  If the
     certificate does not contain the basicConstraints extension
     GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_ca_status
-----------------------------

 -- Function: int gnutls_x509_crt_get_ca_status (gnutls_x509_crt_t CERT,
          unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will return certificates CA status, by reading the
     basicConstraints X.509 extension (2.5.29.19).  If the certificate
     is a CA a positive value will be returned, or (0) if the
     certificate does not have CA flag set.

     Use 'gnutls_x509_crt_get_basic_constraints()' if you want to read
     the pathLenConstraint field too.

     *Returns:* If the certificate is a CA a positive value will be
     returned, or (0) if the certificate does not have CA flag set.  A
     negative error code may be returned in case of errors.  If the
     certificate does not contain the basicConstraints extension
     GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_crl_dist_points
-----------------------------------

 -- Function: int gnutls_x509_crt_get_crl_dist_points (gnutls_x509_crt_t
          CERT, unsigned int SEQ, void * SAN, size_t * SAN_SIZE,
          unsigned int * REASON_FLAGS, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the distribution point (0 for
     the first one, 1 for the second etc.)

     SAN: is the place where the distribution point will be copied to

     SAN_SIZE: holds the size of ret.

     REASON_FLAGS: Revocation reasons.  An ORed sequence of flags from
     'gnutls_x509_crl_reason_flags_t' .

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function retrieves the CRL distribution points (2.5.29.31),
     contained in the given certificate in the X509v3 Certificate
     Extensions.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' and updates 'ret_size' if
     'ret_size' is not enough to hold the distribution point, or the
     type of the distribution point if everything was ok.  The type is
     one of the enumerated 'gnutls_x509_subject_alt_name_t' .  If the
     certificate does not have an Alternative name with the specified
     sequence number then 'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is
     returned.

gnutls_x509_crt_get_dn
----------------------

 -- Function: int gnutls_x509_crt_get_dn (gnutls_x509_crt_t CERT, char *
          BUF, size_t * BUF_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     BUF: a pointer to a structure to hold the name (may be null)

     BUF_SIZE: initially holds the size of 'buf'

     This function will copy the name of the Certificate in the provided
     buffer.  The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
     described in RFC4514.  The output string will be ASCII or UTF-8
     encoded, depending on the certificate data.

     If 'buf' is null then only the size will be filled.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the 'buf_size' will be updated
     with the required size.  On success 0 is returned.

gnutls_x509_crt_get_dn2
-----------------------

 -- Function: int gnutls_x509_crt_get_dn2 (gnutls_x509_crt_t CERT,
          gnutls_datum_t * DN)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     DN: a pointer to a structure to hold the name

     This function will allocate buffer and copy the name of the
     Certificate.  The name will be in the form "C=xxxx,O=yyyy,CN=zzzz"
     as described in RFC4514.  The output string will be ASCII or UTF-8
     encoded, depending on the certificate data.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  and a negative error code on
     error.

     *Since:* 3.1.10

gnutls_x509_crt_get_dn_by_oid
-----------------------------

 -- Function: int gnutls_x509_crt_get_dn_by_oid (gnutls_x509_crt_t CERT,
          const char * OID, int INDX, unsigned int RAW_FLAG, void * BUF,
          size_t * BUF_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     OID: holds an Object Identified in null terminated string

     INDX: In case multiple same OIDs exist in the RDN, this specifies
     which to send.  Use (0) to get the first one.

     RAW_FLAG: If non-zero returns the raw DER data of the DN part.

     BUF: a pointer where the DN part will be copied (may be null).

     BUF_SIZE: initially holds the size of 'buf'

     This function will extract the part of the name of the Certificate
     subject specified by the given OID. The output, if the raw flag is
     not used, will be encoded as described in RFC4514.  Thus a string
     that is ASCII or UTF-8 encoded, depending on the certificate data.

     Some helper macros with popular OIDs can be found in gnutls/x509.h
     If raw flag is (0), this function will only return known OIDs as
     text.  Other OIDs will be DER encoded, as described in RFC4514 - in
     hex format with a '#' prefix.  You can check about known OIDs using
     'gnutls_x509_dn_oid_known()' .

     If 'buf' is null then only the size will be filled.  If the
     'raw_flag' is not specified the output is always null terminated,
     although the 'buf_size' will not include the null character.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the 'buf_size' will be updated
     with the required size.  'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if
     there are no data in the current index.  On success 0 is returned.

gnutls_x509_crt_get_dn_oid
--------------------------

 -- Function: int gnutls_x509_crt_get_dn_oid (gnutls_x509_crt_t CERT,
          int INDX, void * OID, size_t * OID_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     INDX: This specifies which OID to return.  Use (0) to get the first
     one.

     OID: a pointer to a buffer to hold the OID (may be null)

     OID_SIZE: initially holds the size of 'oid'

     This function will extract the OIDs of the name of the Certificate
     subject specified by the given index.

     If 'oid' is null then only the size will be filled.  The 'oid'
     returned will be null terminated, although 'oid_size' will not
     account for the trailing null.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the 'buf_size' will be updated
     with the required size.  'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if
     there are no data in the current index.  On success 0 is returned.

gnutls_x509_crt_get_expiration_time
-----------------------------------

 -- Function: time_t gnutls_x509_crt_get_expiration_time
          (gnutls_x509_crt_t CERT)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     This function will return the time this Certificate was or will be
     expired.

     The no well defined expiration time can be checked against with the
     'GNUTLS_X509_NO_WELL_DEFINED_EXPIRATION' macro.

     *Returns:* expiration time, or (time_t)-1 on error.

gnutls_x509_crt_get_extension_by_oid
------------------------------------

 -- Function: int gnutls_x509_crt_get_extension_by_oid
          (gnutls_x509_crt_t CERT, const char * OID, int INDX, void *
          BUF, size_t * BUF_SIZE, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     OID: holds an Object Identified in null terminated string

     INDX: In case multiple same OIDs exist in the extensions, this
     specifies which to send.  Use (0) to get the first one.

     BUF: a pointer to a structure to hold the name (may be null)

     BUF_SIZE: initially holds the size of 'buf'

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will return the extension specified by the OID in the
     certificate.  The extensions will be returned as binary data DER
     encoded, in the provided buffer.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If the certificate
     does not contain the specified extension
     GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_x509_crt_get_extension_by_oid2
-------------------------------------

 -- Function: int gnutls_x509_crt_get_extension_by_oid2
          (gnutls_x509_crt_t CERT, const char * OID, int INDX,
          gnutls_datum_t * OUTPUT, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     OID: holds an Object Identified in null terminated string

     INDX: In case multiple same OIDs exist in the extensions, this
     specifies which to send.  Use (0) to get the first one.

     OUTPUT: will hold the allocated extension data

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will return the extension specified by the OID in the
     certificate.  The extensions will be returned as binary data DER
     encoded, in the provided buffer.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If the certificate
     does not contain the specified extension
     GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

     *Since:* 3.3.8

gnutls_x509_crt_get_extension_data
----------------------------------

 -- Function: int gnutls_x509_crt_get_extension_data (gnutls_x509_crt_t
          CERT, int INDX, void * DATA, size_t * SIZEOF_DATA)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     INDX: Specifies which extension OID to send.  Use (0) to get the
     first one.

     DATA: a pointer to a structure to hold the data (may be null)

     SIZEOF_DATA: initially holds the size of 'data'

     This function will return the requested extension data in the
     certificate.  The extension data will be stored in the provided
     buffer.

     Use 'gnutls_x509_crt_get_extension_info()' to extract the OID and
     critical flag.  Use 'gnutls_x509_crt_get_extension_by_oid()'
     instead, if you want to get data indexed by the extension OID
     rather than sequence.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If you have reached
     the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

gnutls_x509_crt_get_extension_data2
-----------------------------------

 -- Function: int gnutls_x509_crt_get_extension_data2 (gnutls_x509_crt_t
          CERT, unsigned INDX, gnutls_datum_t * DATA)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     INDX: Specifies which extension OID to read.  Use (0) to get the
     first one.

     DATA: will contain the extension DER-encoded data

     This function will return the requested by the index extension data
     in the certificate.  The extension data will be allocated using
     'gnutls_malloc()' .

     Use 'gnutls_x509_crt_get_extension_info()' to extract the OID.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If you have reached
     the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

gnutls_x509_crt_get_extension_info
----------------------------------

 -- Function: int gnutls_x509_crt_get_extension_info (gnutls_x509_crt_t
          CERT, int INDX, void * OID, size_t * OID_SIZE, unsigned int *
          CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     INDX: Specifies which extension OID to send.  Use (0) to get the
     first one.

     OID: a pointer to a structure to hold the OID

     OID_SIZE: initially holds the maximum size of 'oid' , on return
     holds actual size of 'oid' .

     CRITICAL: output variable with critical flag, may be NULL.

     This function will return the requested extension OID in the
     certificate, and the critical flag for it.  The extension OID will
     be stored as a string in the provided buffer.  Use
     'gnutls_x509_crt_get_extension()' to extract the data.

     If the buffer provided is not long enough to hold the output, then
     'oid_size' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER' will be
     returned.  The 'oid' returned will be null terminated, although
     'oid_size' will not account for the trailing null.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If you have reached
     the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

gnutls_x509_crt_get_extension_oid
---------------------------------

 -- Function: int gnutls_x509_crt_get_extension_oid (gnutls_x509_crt_t
          CERT, int INDX, void * OID, size_t * OID_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     INDX: Specifies which extension OID to send.  Use (0) to get the
     first one.

     OID: a pointer to a structure to hold the OID (may be null)

     OID_SIZE: initially holds the size of 'oid'

     This function will return the requested extension OID in the
     certificate.  The extension OID will be stored as a string in the
     provided buffer.

     The 'oid' returned will be null terminated, although 'oid_size'
     will not account for the trailing null.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.  If you have reached
     the last extension available
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be returned.

gnutls_x509_crt_get_fingerprint
-------------------------------

 -- Function: int gnutls_x509_crt_get_fingerprint (gnutls_x509_crt_t
          CERT, gnutls_digest_algorithm_t ALGO, void * BUF, size_t *
          BUF_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     ALGO: is a digest algorithm

     BUF: a pointer to a structure to hold the fingerprint (may be null)

     BUF_SIZE: initially holds the size of 'buf'

     This function will calculate and copy the certificate's fingerprint
     in the provided buffer.  The fingerprint is a hash of the
     DER-encoded data of the certificate.

     If the buffer is null then only the size will be filled.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the *buf_size will be updated
     with the required size.  On success 0 is returned.

gnutls_x509_crt_get_issuer
--------------------------

 -- Function: int gnutls_x509_crt_get_issuer (gnutls_x509_crt_t CERT,
          gnutls_x509_dn_t * DN)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     DN: output variable with pointer to uint8_t DN

     Return the Certificate's Issuer DN as a 'gnutls_x509_dn_t' data
     type, that can be decoded using 'gnutls_x509_dn_get_rdn_ava()' .

     Note that 'dn' should be treated as constant.  Because it points
     into the 'cert' object, you should not use 'dn' after 'cert' is
     deallocated.

     *Returns:* Returns 0 on success, or an error code.

gnutls_x509_crt_get_issuer_alt_name
-----------------------------------

 -- Function: int gnutls_x509_crt_get_issuer_alt_name (gnutls_x509_crt_t
          CERT, unsigned int SEQ, void * IAN, size_t * IAN_SIZE,
          unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     IAN: is the place where the alternative name will be copied to

     IAN_SIZE: holds the size of ian.

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function retrieves the Issuer Alternative Name (2.5.29.18),
     contained in the given certificate in the X509v3 Certificate
     Extensions.

     When the SAN type is otherName, it will extract the data in the
     otherName's value field, and 'GNUTLS_SAN_OTHERNAME' is returned.
     You may use 'gnutls_x509_crt_get_subject_alt_othername_oid()' to
     get the corresponding OID and the "virtual" SAN types (e.g.,
     'GNUTLS_SAN_OTHERNAME_XMPP' ).

     If an otherName OID is known, the data will be decoded.  Otherwise
     the returned data will be DER encoded, and you will have to decode
     it yourself.  Currently, only the RFC 3920 id-on-xmppAddr Issuer
     AltName is recognized.

     *Returns:* the alternative issuer name type on success, one of the
     enumerated 'gnutls_x509_subject_alt_name_t' .  It will return
     'GNUTLS_E_SHORT_MEMORY_BUFFER' if 'ian_size' is not large enough to
     hold the value.  In that case 'ian_size' will be updated with the
     required size.  If the certificate does not have an Alternative
     name with the specified sequence number then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Since:* 2.10.0

gnutls_x509_crt_get_issuer_alt_name2
------------------------------------

 -- Function: int gnutls_x509_crt_get_issuer_alt_name2
          (gnutls_x509_crt_t CERT, unsigned int SEQ, void * IAN, size_t
          * IAN_SIZE, unsigned int * IAN_TYPE, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     IAN: is the place where the alternative name will be copied to

     IAN_SIZE: holds the size of ret.

     IAN_TYPE: holds the type of the alternative name (one of
     gnutls_x509_subject_alt_name_t).

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the alternative names, contained in the
     given certificate.  It is the same as
     'gnutls_x509_crt_get_issuer_alt_name()' except for the fact that it
     will return the type of the alternative name in 'ian_type' even if
     the function fails for some reason (i.e.  the buffer provided is
     not enough).

     *Returns:* the alternative issuer name type on success, one of the
     enumerated 'gnutls_x509_subject_alt_name_t' .  It will return
     'GNUTLS_E_SHORT_MEMORY_BUFFER' if 'ian_size' is not large enough to
     hold the value.  In that case 'ian_size' will be updated with the
     required size.  If the certificate does not have an Alternative
     name with the specified sequence number then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Since:* 2.10.0

gnutls_x509_crt_get_issuer_alt_othername_oid
--------------------------------------------

 -- Function: int gnutls_x509_crt_get_issuer_alt_othername_oid
          (gnutls_x509_crt_t CERT, unsigned int SEQ, void * RET, size_t
          * RET_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     RET: is the place where the otherName OID will be copied to

     RET_SIZE: holds the size of ret.

     This function will extract the type OID of an otherName Subject
     Alternative Name, contained in the given certificate, and return
     the type as an enumerated element.

     If 'oid' is null then only the size will be filled.  The 'oid'
     returned will be null terminated, although 'oid_size' will not
     account for the trailing null.

     This function is only useful if
     'gnutls_x509_crt_get_issuer_alt_name()' returned
     'GNUTLS_SAN_OTHERNAME' .

     *Returns:* the alternative issuer name type on success, one of the
     enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
     will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types, e.g.
     'GNUTLS_SAN_OTHERNAME_XMPP' , and 'GNUTLS_SAN_OTHERNAME' for
     unknown OIDs.  It will return 'GNUTLS_E_SHORT_MEMORY_BUFFER' if
     'ret_size' is not large enough to hold the value.  In that case
     'ret_size' will be updated with the required size.  If the
     certificate does not have an Alternative name with the specified
     sequence number and with the otherName type then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

     *Since:* 2.10.0

gnutls_x509_crt_get_issuer_dn
-----------------------------

 -- Function: int gnutls_x509_crt_get_issuer_dn (gnutls_x509_crt_t CERT,
          char * BUF, size_t * BUF_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     BUF: a pointer to a structure to hold the name (may be null)

     BUF_SIZE: initially holds the size of 'buf'

     This function will copy the name of the Certificate issuer in the
     provided buffer.  The name will be in the form
     "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514.  The output string
     will be ASCII or UTF-8 encoded, depending on the certificate data.

     If 'buf' is null then only the size will be filled.

     *Returns:* GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is
     not long enough, and in that case the 'buf_size' will be updated
     with the required size.  On success 0 is returned.

gnutls_x509_crt_get_issuer_dn2
------------------------------

 -- Function: int gnutls_x509_crt_get_issuer_dn2 (gnutls_x509_crt_t
          CERT, gnutls_datum_t * DN)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     DN: a pointer to a structure to hold the name

     This function will allocate buffer and copy the name of issuer of
     the Certificate.  The name will be in the form
     "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514.  The output string
     will be ASCII or UTF-8 encoded, depending on the certificate data.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  and a negative error code on
     error.

     *Since:* 3.1.10

gnutls_x509_crt_get_issuer_dn_by_oid
------------------------------------

 -- Function: int gnutls_x509_crt_get_issuer_dn_by_oid
          (gnutls_x509_crt_t CERT, const char * OID, int INDX, unsigned
          int RAW_FLAG, void * BUF, size_t * BUF_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     OID: holds an Object Identified in null terminated string

     INDX: In case multiple same OIDs exist in the RDN, this specifies
     which to send.  Use (0) to get the first one.

     RAW_FLAG: If non-zero returns the raw DER data of the DN part.

     BUF: a pointer to a structure to hold the name (may be null)

     BUF_SIZE: initially holds the size of 'buf'

     This function will extract the part of the name of the Certificate
     issuer specified by the given OID. The output, if the raw flag is
     not used, will be encoded as described in RFC4514.  Thus a string
     that is ASCII or UTF-8 encoded, depending on the certificate data.

     Some helper macros with popular OIDs can be found in gnutls/x509.h
     If raw flag is (0), this function will only return known OIDs as
     text.  Other OIDs will be DER encoded, as described in RFC4514 - in
     hex format with a '#' prefix.  You can check about known OIDs using
     'gnutls_x509_dn_oid_known()' .

     If 'buf' is null then only the size will be filled.  If the
     'raw_flag' is not specified the output is always null terminated,
     although the 'buf_size' will not include the null character.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the 'buf_size' will be updated
     with the required size.  'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if
     there are no data in the current index.  On success 0 is returned.

gnutls_x509_crt_get_issuer_dn_oid
---------------------------------

 -- Function: int gnutls_x509_crt_get_issuer_dn_oid (gnutls_x509_crt_t
          CERT, int INDX, void * OID, size_t * OID_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     INDX: This specifies which OID to return.  Use (0) to get the first
     one.

     OID: a pointer to a buffer to hold the OID (may be null)

     OID_SIZE: initially holds the size of 'oid'

     This function will extract the OIDs of the name of the Certificate
     issuer specified by the given index.

     If 'oid' is null then only the size will be filled.  The 'oid'
     returned will be null terminated, although 'oid_size' will not
     account for the trailing null.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the 'buf_size' will be updated
     with the required size.  'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if
     there are no data in the current index.  On success 0 is returned.

gnutls_x509_crt_get_issuer_unique_id
------------------------------------

 -- Function: int gnutls_x509_crt_get_issuer_unique_id
          (gnutls_x509_crt_t CRT, char * BUF, size_t * BUF_SIZE)
     CRT: Holds the certificate

     BUF: user allocated memory buffer, will hold the unique id

     BUF_SIZE: size of user allocated memory buffer (on input), will
     hold actual size of the unique ID on return.

     This function will extract the issuerUniqueID value (if present)
     for the given certificate.

     If the user allocated memory buffer is not large enough to hold the
     full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error
     will be returned, and buf_size will be set to the actual length.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

     *Since:* 2.12.0

gnutls_x509_crt_get_key_id
--------------------------

 -- Function: int gnutls_x509_crt_get_key_id (gnutls_x509_crt_t CRT,
          unsigned int FLAGS, unsigned char * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     CRT: Holds the certificate

     FLAGS: should be 0 for now

     OUTPUT_DATA: will contain the key ID

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will return a unique ID that depends on the public
     key parameters.  This ID can be used in checking whether a
     certificate corresponds to the given private key.

     If the buffer provided is not long enough to hold the output, then
     *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
     be returned.  The output will normally be a SHA-1 hash output,
     which is 20 bytes.

     *Returns:* In case of failure a negative error code will be
     returned, and 0 on success.

gnutls_x509_crt_get_key_purpose_oid
-----------------------------------

 -- Function: int gnutls_x509_crt_get_key_purpose_oid (gnutls_x509_crt_t
          CERT, int INDX, void * OID, size_t * OID_SIZE, unsigned int *
          CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     INDX: This specifies which OID to return.  Use (0) to get the first
     one.

     OID: a pointer to a buffer to hold the OID (may be null)

     OID_SIZE: initially holds the size of 'oid'

     CRITICAL: output flag to indicate criticality of extension

     This function will extract the key purpose OIDs of the Certificate
     specified by the given index.  These are stored in the Extended Key
     Usage extension (2.5.29.37) See the GNUTLS_KP_* definitions for
     human readable names.

     If 'oid' is null then only the size will be filled.  The 'oid'
     returned will be null terminated, although 'oid_size' will not
     account for the trailing null.

     *Returns:* 'GNUTLS_E_SHORT_MEMORY_BUFFER' if the provided buffer is
     not long enough, and in that case the *oid_size will be updated
     with the required size.  On success 0 is returned.

gnutls_x509_crt_get_key_usage
-----------------------------

 -- Function: int gnutls_x509_crt_get_key_usage (gnutls_x509_crt_t CERT,
          unsigned int * KEY_USAGE, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     KEY_USAGE: where the key usage bits will be stored

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will return certificate's key usage, by reading the
     keyUsage X.509 extension (2.5.29.15).  The key usage value will
     ORed values of the: 'GNUTLS_KEY_DIGITAL_SIGNATURE' ,
     'GNUTLS_KEY_NON_REPUDIATION' , 'GNUTLS_KEY_KEY_ENCIPHERMENT' ,
     'GNUTLS_KEY_DATA_ENCIPHERMENT' , 'GNUTLS_KEY_KEY_AGREEMENT' ,
     'GNUTLS_KEY_KEY_CERT_SIGN' , 'GNUTLS_KEY_CRL_SIGN' ,
     'GNUTLS_KEY_ENCIPHER_ONLY' , 'GNUTLS_KEY_DECIPHER_ONLY' .

     *Returns:* the certificate key usage, or a negative error code in
     case of parsing error.  If the certificate does not contain the
     keyUsage extension 'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be
     returned.

gnutls_x509_crt_get_name_constraints
------------------------------------

 -- Function: int gnutls_x509_crt_get_name_constraints
          (gnutls_x509_crt_t CRT, gnutls_x509_name_constraints_t NC,
          unsigned int FLAGS, unsigned int * CRITICAL)
     CRT: should contain a 'gnutls_x509_crt_t' structure

     NC: The nameconstraints intermediate structure

     FLAGS: zero or 'GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND'

     CRITICAL: the extension status

     This function will return an intermediate structure containing the
     name constraints of the provided CA certificate.  That structure
     can be used in combination with
     'gnutls_x509_name_constraints_check()' to verify whether a server's
     name is in accordance with the constraints.

     When the 'flags' is set to 'GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND' ,
     then if the 'nc' structure is empty this function will behave
     identically as if the flag was not set.  Otherwise if there are
     elements in the 'nc' structure then only the excluded constraints
     will be appended to the constraints.

     Note that 'nc' must be initialized prior to calling this function.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_crt_get_pk_algorithm
--------------------------------

 -- Function: int gnutls_x509_crt_get_pk_algorithm (gnutls_x509_crt_t
          CERT, unsigned int * BITS)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     BITS: if bits is non null it will hold the size of the parameters'
     in bits

     This function will return the public key algorithm of an X.509
     certificate.

     If bits is non null, it should have enough size to hold the
     parameters size in bits.  For RSA the bits returned is the modulus.
     For DSA the bits returned are of the public exponent.

     *Returns:* a member of the 'gnutls_pk_algorithm_t' enumeration on
     success, or a negative error code on error.

gnutls_x509_crt_get_pk_dsa_raw
------------------------------

 -- Function: int gnutls_x509_crt_get_pk_dsa_raw (gnutls_x509_crt_t CRT,
          gnutls_datum_t * P, gnutls_datum_t * Q, gnutls_datum_t * G,
          gnutls_datum_t * Y)
     CRT: Holds the certificate

     P: will hold the p

     Q: will hold the q

     G: will hold the g

     Y: will hold the y

     This function will export the DSA public key's parameters found in
     the given certificate.  The new parameters will be allocated using
     'gnutls_malloc()' and will be stored in the appropriate datum.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

gnutls_x509_crt_get_pk_rsa_raw
------------------------------

 -- Function: int gnutls_x509_crt_get_pk_rsa_raw (gnutls_x509_crt_t CRT,
          gnutls_datum_t * M, gnutls_datum_t * E)
     CRT: Holds the certificate

     M: will hold the modulus

     E: will hold the public exponent

     This function will export the RSA public key's parameters found in
     the given structure.  The new parameters will be allocated using
     'gnutls_malloc()' and will be stored in the appropriate datum.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

gnutls_x509_crt_get_policy
--------------------------

 -- Function: int gnutls_x509_crt_get_policy (gnutls_x509_crt_t CRT, int
          INDX, struct gnutls_x509_policy_st * POLICY, unsigned int *
          CRITICAL)
     CRT: should contain a 'gnutls_x509_crt_t' structure

     INDX: This specifies which policy to return.  Use (0) to get the
     first one.

     POLICY: A pointer to a policy structure.

     CRITICAL: will be non-zero if the extension is marked as critical

     This function will extract the certificate policy (extension
     2.5.29.32) specified by the given index.

     The policy returned by this function must be deinitialized by using
     'gnutls_x509_policy_release()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.1.5

gnutls_x509_crt_get_private_key_usage_period
--------------------------------------------

 -- Function: int gnutls_x509_crt_get_private_key_usage_period
          (gnutls_x509_crt_t CERT, time_t * ACTIVATION, time_t *
          EXPIRATION, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     ACTIVATION: The activation time

     EXPIRATION: The expiration time

     CRITICAL: the extension status

     This function will return the expiration and activation times of
     the private key of the certificate.  It relies on the PKIX
     extension 2.5.29.16 being present.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

gnutls_x509_crt_get_proxy
-------------------------

 -- Function: int gnutls_x509_crt_get_proxy (gnutls_x509_crt_t CERT,
          unsigned int * CRITICAL, int * PATHLEN, char **
          POLICYLANGUAGE, char ** POLICY, size_t * SIZEOF_POLICY)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     CRITICAL: will be non-zero if the extension is marked as critical

     PATHLEN: pointer to output integer indicating path length (may be
     NULL), non-negative error codes indicate a present
     pCPathLenConstraint field and the actual value, -1 indicate that
     the field is absent.

     POLICYLANGUAGE: output variable with OID of policy language

     POLICY: output variable with policy data

     SIZEOF_POLICY: output variable size of policy data

     This function will get information from a proxy certificate.  It
     reads the ProxyCertInfo X.509 extension (1.3.6.1.5.5.7.1.14).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_x509_crt_get_raw_dn
--------------------------

 -- Function: int gnutls_x509_crt_get_raw_dn (gnutls_x509_crt_t CERT,
          gnutls_datum_t * DN)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     DN: will hold the starting point of the DN

     This function will return a pointer to the DER encoded DN structure
     and the length.  This points to allocated data that must be free'd
     using 'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  or a negative error code on
     error.

gnutls_x509_crt_get_raw_issuer_dn
---------------------------------

 -- Function: int gnutls_x509_crt_get_raw_issuer_dn (gnutls_x509_crt_t
          CERT, gnutls_datum_t * DN)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     DN: will hold the starting point of the DN

     This function will return a pointer to the DER encoded DN structure
     and the length.  This points to allocated data that must be free'd
     using 'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.or a negative error code on error.

gnutls_x509_crt_get_serial
--------------------------

 -- Function: int gnutls_x509_crt_get_serial (gnutls_x509_crt_t CERT,
          void * RESULT, size_t * RESULT_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     RESULT: The place where the serial number will be copied

     RESULT_SIZE: Holds the size of the result field.

     This function will return the X.509 certificate's serial number.
     This is obtained by the X509 Certificate serialNumber field.
     Serial is not always a 32 or 64bit number.  Some CAs use large
     serial numbers, thus it may be wise to handle it as something
     uint8_t.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_get_signature
-----------------------------

 -- Function: int gnutls_x509_crt_get_signature (gnutls_x509_crt_t CERT,
          char * SIG, size_t * SIG_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SIG: a pointer where the signature part will be copied (may be
     null).

     SIG_SIZE: initially holds the size of 'sig'

     This function will extract the signature field of a certificate.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  and a negative error code on
     error.

gnutls_x509_crt_get_signature_algorithm
---------------------------------------

 -- Function: int gnutls_x509_crt_get_signature_algorithm
          (gnutls_x509_crt_t CERT)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     This function will return a value of the 'gnutls_sign_algorithm_t'
     enumeration that is the signature algorithm that has been used to
     sign this certificate.

     *Returns:* a 'gnutls_sign_algorithm_t' value, or a negative error
     code on error.

gnutls_x509_crt_get_subject
---------------------------

 -- Function: int gnutls_x509_crt_get_subject (gnutls_x509_crt_t CERT,
          gnutls_x509_dn_t * DN)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     DN: output variable with pointer to uint8_t DN.

     Return the Certificate's Subject DN as a 'gnutls_x509_dn_t' data
     type, that can be decoded using 'gnutls_x509_dn_get_rdn_ava()' .

     Note that 'dn' should be treated as constant.  Because it points
     into the 'cert' object, you should not use 'dn' after 'cert' is
     deallocated.

     *Returns:* Returns 0 on success, or an error code.

gnutls_x509_crt_get_subject_alt_name
------------------------------------

 -- Function: int gnutls_x509_crt_get_subject_alt_name
          (gnutls_x509_crt_t CERT, unsigned int SEQ, void * SAN, size_t
          * SAN_SIZE, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     SAN: is the place where the alternative name will be copied to

     SAN_SIZE: holds the size of san.

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function retrieves the Alternative Name (2.5.29.17), contained
     in the given certificate in the X509v3 Certificate Extensions.

     When the SAN type is otherName, it will extract the data in the
     otherName's value field, and 'GNUTLS_SAN_OTHERNAME' is returned.
     You may use 'gnutls_x509_crt_get_subject_alt_othername_oid()' to
     get the corresponding OID and the "virtual" SAN types (e.g.,
     'GNUTLS_SAN_OTHERNAME_XMPP' ).

     If an otherName OID is known, the data will be decoded.  Otherwise
     the returned data will be DER encoded, and you will have to decode
     it yourself.  Currently, only the RFC 3920 id-on-xmppAddr SAN is
     recognized.

     *Returns:* the alternative subject name type on success, one of the
     enumerated 'gnutls_x509_subject_alt_name_t' .  It will return
     'GNUTLS_E_SHORT_MEMORY_BUFFER' if 'san_size' is not large enough to
     hold the value.  In that case 'san_size' will be updated with the
     required size.  If the certificate does not have an Alternative
     name with the specified sequence number then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

gnutls_x509_crt_get_subject_alt_name2
-------------------------------------

 -- Function: int gnutls_x509_crt_get_subject_alt_name2
          (gnutls_x509_crt_t CERT, unsigned int SEQ, void * SAN, size_t
          * SAN_SIZE, unsigned int * SAN_TYPE, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     SAN: is the place where the alternative name will be copied to

     SAN_SIZE: holds the size of ret.

     SAN_TYPE: holds the type of the alternative name (one of
     gnutls_x509_subject_alt_name_t).

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the alternative names, contained in the
     given certificate.  It is the same as
     'gnutls_x509_crt_get_subject_alt_name()' except for the fact that
     it will return the type of the alternative name in 'san_type' even
     if the function fails for some reason (i.e.  the buffer provided is
     not enough).

     *Returns:* the alternative subject name type on success, one of the
     enumerated 'gnutls_x509_subject_alt_name_t' .  It will return
     'GNUTLS_E_SHORT_MEMORY_BUFFER' if 'san_size' is not large enough to
     hold the value.  In that case 'san_size' will be updated with the
     required size.  If the certificate does not have an Alternative
     name with the specified sequence number then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

gnutls_x509_crt_get_subject_alt_othername_oid
---------------------------------------------

 -- Function: int gnutls_x509_crt_get_subject_alt_othername_oid
          (gnutls_x509_crt_t CERT, unsigned int SEQ, void * OID, size_t
          * OID_SIZE)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     SEQ: specifies the sequence number of the alt name (0 for the first
     one, 1 for the second etc.)

     OID: is the place where the otherName OID will be copied to

     OID_SIZE: holds the size of ret.

     This function will extract the type OID of an otherName Subject
     Alternative Name, contained in the given certificate, and return
     the type as an enumerated element.

     This function is only useful if
     'gnutls_x509_crt_get_subject_alt_name()' returned
     'GNUTLS_SAN_OTHERNAME' .

     If 'oid' is null then only the size will be filled.  The 'oid'
     returned will be null terminated, although 'oid_size' will not
     account for the trailing null.

     *Returns:* the alternative subject name type on success, one of the
     enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
     will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types, e.g.
     'GNUTLS_SAN_OTHERNAME_XMPP' , and 'GNUTLS_SAN_OTHERNAME' for
     unknown OIDs.  It will return 'GNUTLS_E_SHORT_MEMORY_BUFFER' if
     'ian_size' is not large enough to hold the value.  In that case
     'ian_size' will be updated with the required size.  If the
     certificate does not have an Alternative name with the specified
     sequence number and with the otherName type then
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' is returned.

gnutls_x509_crt_get_subject_key_id
----------------------------------

 -- Function: int gnutls_x509_crt_get_subject_key_id (gnutls_x509_crt_t
          CERT, void * RET, size_t * RET_SIZE, unsigned int * CRITICAL)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     RET: The place where the identifier will be copied

     RET_SIZE: Holds the size of the result field.

     CRITICAL: will be non-zero if the extension is marked as critical
     (may be null)

     This function will return the X.509v3 certificate's subject key
     identifier.  This is obtained by the X.509 Subject Key identifier
     extension field (2.5.29.14).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

gnutls_x509_crt_get_subject_unique_id
-------------------------------------

 -- Function: int gnutls_x509_crt_get_subject_unique_id
          (gnutls_x509_crt_t CRT, char * BUF, size_t * BUF_SIZE)
     CRT: Holds the certificate

     BUF: user allocated memory buffer, will hold the unique id

     BUF_SIZE: size of user allocated memory buffer (on input), will
     hold actual size of the unique ID on return.

     This function will extract the subjectUniqueID value (if present)
     for the given certificate.

     If the user allocated memory buffer is not large enough to hold the
     full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error
     will be returned, and buf_size will be set to the actual length.

     *Returns:* 'GNUTLS_E_SUCCESS' on success, otherwise a negative
     error code.

gnutls_x509_crt_get_version
---------------------------

 -- Function: int gnutls_x509_crt_get_version (gnutls_x509_crt_t CERT)
     CERT: should contain a 'gnutls_x509_crt_t' structure

     This function will return the version of the specified Certificate.

     *Returns:* version of certificate, or a negative error code on
     error.

gnutls_x509_crt_import
----------------------

 -- Function: int gnutls_x509_crt_import (gnutls_x509_crt_t CERT, const
          gnutls_datum_t * DATA, gnutls_x509_crt_fmt_t FORMAT)
     CERT: The structure to store the parsed certificate.

     DATA: The DER or PEM encoded certificate.

     FORMAT: One of DER or PEM

     This function will convert the given DER or PEM encoded Certificate
     to the native gnutls_x509_crt_t format.  The output will be stored
     in 'cert' .

     If the Certificate is PEM encoded it should have a header of "X509
     CERTIFICATE", or "CERTIFICATE".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_init
--------------------

 -- Function: int gnutls_x509_crt_init (gnutls_x509_crt_t * CERT)
     CERT: The structure to be initialized

     This function will initialize an X.509 certificate structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_list_import
---------------------------

 -- Function: int gnutls_x509_crt_list_import (gnutls_x509_crt_t *
          CERTS, unsigned int * CERT_MAX, const gnutls_datum_t * DATA,
          gnutls_x509_crt_fmt_t FORMAT, unsigned int FLAGS)
     CERTS: The structures to store the parsed certificate.  Must not be
     initialized.

     CERT_MAX: Initially must hold the maximum number of certs.  It will
     be updated with the number of certs available.

     DATA: The PEM encoded certificate.

     FORMAT: One of DER or PEM.

     FLAGS: must be (0) or an OR'd sequence of
     gnutls_certificate_import_flags.

     This function will convert the given PEM encoded certificate list
     to the native gnutls_x509_crt_t format.  The output will be stored
     in 'certs' .  They will be automatically initialized.

     The flag 'GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED' will cause
     import to fail if the certificates in the provided buffer are more
     than the available structures.  The
     'GNUTLS_X509_CRT_LIST_FAIL_IF_UNSORTED' flag will cause the
     function to fail if the provided list is not sorted from subject to
     issuer.

     If the Certificate is PEM encoded it should have a header of "X509
     CERTIFICATE", or "CERTIFICATE".

     *Returns:* the number of certificates read or a negative error
     value.

gnutls_x509_crt_list_import2
----------------------------

 -- Function: int gnutls_x509_crt_list_import2 (gnutls_x509_crt_t **
          CERTS, unsigned int * SIZE, const gnutls_datum_t * DATA,
          gnutls_x509_crt_fmt_t FORMAT, unsigned int FLAGS)
     CERTS: The structures to store the parsed certificate.  Must not be
     initialized.

     SIZE: It will contain the size of the list.

     DATA: The PEM encoded certificate.

     FORMAT: One of DER or PEM.

     FLAGS: must be (0) or an OR'd sequence of
     gnutls_certificate_import_flags.

     This function will convert the given PEM encoded certificate list
     to the native gnutls_x509_crt_t format.  The output will be stored
     in 'certs' which will allocated and initialized.

     If the Certificate is PEM encoded it should have a header of "X509
     CERTIFICATE", or "CERTIFICATE".

     To deinitialize 'certs' , you need to deinitialize each crt
     structure independently, and use 'gnutls_free()' at

     *Returns:* the number of certificates read or a negative error
     value.

     *Since:* 3.0

gnutls_x509_crt_list_verify
---------------------------

 -- Function: int gnutls_x509_crt_list_verify (const gnutls_x509_crt_t *
          CERT_LIST, int CERT_LIST_LENGTH, const gnutls_x509_crt_t *
          CA_LIST, int CA_LIST_LENGTH, const gnutls_x509_crl_t *
          CRL_LIST, int CRL_LIST_LENGTH, unsigned int FLAGS, unsigned
          int * VERIFY)
     CERT_LIST: is the certificate list to be verified

     CERT_LIST_LENGTH: holds the number of certificate in cert_list

     CA_LIST: is the CA list which will be used in verification

     CA_LIST_LENGTH: holds the number of CA certificate in CA_list

     CRL_LIST: holds a list of CRLs.

     CRL_LIST_LENGTH: the length of CRL list.

     FLAGS: Flags that may be used to change the verification algorithm.
     Use OR of the gnutls_certificate_verify_flags enumerations.

     VERIFY: will hold the certificate verification output.

     This function will try to verify the given certificate list and
     return its status.  If no flags are specified (0), this function
     will use the basicConstraints (2.5.29.19) PKIX extension.  This
     means that only a certificate authority is allowed to sign a
     certificate.

     You must also check the peer's name in order to check if the
     verified certificate belongs to the actual peer.

     The certificate verification output will be put in 'verify' and
     will be one or more of the gnutls_certificate_status_t enumerated
     elements bitwise or'd.  For a more detailed verification status use
     'gnutls_x509_crt_verify()' per list element.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_print
---------------------

 -- Function: int gnutls_x509_crt_print (gnutls_x509_crt_t CERT,
          gnutls_certificate_print_formats_t FORMAT, gnutls_datum_t *
          OUT)
     CERT: The structure to be printed

     FORMAT: Indicate the format to use

     OUT: Newly allocated datum with null terminated string.

     This function will pretty print a X.509 certificate, suitable for
     display to a human.

     If the format is 'GNUTLS_CRT_PRINT_FULL' then all fields of the
     certificate will be output, on multiple lines.  The
     'GNUTLS_CRT_PRINT_ONELINE' format will generate one line with some
     selected fields, which is useful for logging purposes.

     The output 'out' needs to be deallocated using 'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_activation_time
-----------------------------------

 -- Function: int gnutls_x509_crt_set_activation_time (gnutls_x509_crt_t
          CERT, time_t ACT_TIME)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     ACT_TIME: The actual time

     This function will set the time this Certificate was or will be
     activated.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_authority_info_access
-----------------------------------------

 -- Function: int gnutls_x509_crt_set_authority_info_access
          (gnutls_x509_crt_t CRT, int WHAT, gnutls_datum_t * DATA)
     CRT: Holds the certificate

     WHAT: what data to get, a 'gnutls_info_access_what_t' type.

     DATA: output data to be freed with 'gnutls_free()' .

     This function sets the Authority Information Access (AIA)
     extension, see RFC 5280 section 4.2.2.1 for more information.

     The type of data stored in 'data' is specified via 'what' which
     should be 'gnutls_info_access_what_t' values.

     If 'what' is 'GNUTLS_IA_OCSP_URI' , 'data' will hold the OCSP URI.
     If 'what' is 'GNUTLS_IA_CAISSUERS_URI' , 'data' will hold the
     caIssuers URI.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0

gnutls_x509_crt_set_authority_key_id
------------------------------------

 -- Function: int gnutls_x509_crt_set_authority_key_id
          (gnutls_x509_crt_t CERT, const void * ID, size_t ID_SIZE)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     ID: The key ID

     ID_SIZE: Holds the size of the key ID field.

     This function will set the X.509 certificate's authority key ID
     extension.  Only the keyIdentifier field can be set with this
     function.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_basic_constraints
-------------------------------------

 -- Function: int gnutls_x509_crt_set_basic_constraints
          (gnutls_x509_crt_t CRT, unsigned int CA, int
          PATHLENCONSTRAINT)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     CA: true(1) or false(0).  Depending on the Certificate authority
     status.

     PATHLENCONSTRAINT: non-negative error codes indicate maximum length
     of path, and negative error codes indicate that the
     pathLenConstraints field should not be present.

     This function will set the basicConstraints certificate extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_ca_status
-----------------------------

 -- Function: int gnutls_x509_crt_set_ca_status (gnutls_x509_crt_t CRT,
          unsigned int CA)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     CA: true(1) or false(0).  Depending on the Certificate authority
     status.

     This function will set the basicConstraints certificate extension.
     Use 'gnutls_x509_crt_set_basic_constraints()' if you want to
     control the pathLenConstraint field too.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_crl_dist_points
-----------------------------------

 -- Function: int gnutls_x509_crt_set_crl_dist_points (gnutls_x509_crt_t
          CRT, gnutls_x509_subject_alt_name_t TYPE, const void *
          DATA_STRING, unsigned int REASON_FLAGS)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     TYPE: is one of the gnutls_x509_subject_alt_name_t enumerations

     DATA_STRING: The data to be set

     REASON_FLAGS: revocation reasons

     This function will set the CRL distribution points certificate
     extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_crl_dist_points2
------------------------------------

 -- Function: int gnutls_x509_crt_set_crl_dist_points2
          (gnutls_x509_crt_t CRT, gnutls_x509_subject_alt_name_t TYPE,
          const void * DATA, unsigned int DATA_SIZE, unsigned int
          REASON_FLAGS)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     TYPE: is one of the gnutls_x509_subject_alt_name_t enumerations

     DATA: The data to be set

     DATA_SIZE: The data size

     REASON_FLAGS: revocation reasons

     This function will set the CRL distribution points certificate
     extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.6.0

gnutls_x509_crt_set_crq
-----------------------

 -- Function: int gnutls_x509_crt_set_crq (gnutls_x509_crt_t CRT,
          gnutls_x509_crq_t CRQ)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     CRQ: holds a certificate request

     This function will set the name and public parameters as well as
     the extensions from the given certificate request to the
     certificate.  Only RSA keys are currently supported.

     Note that this function will only set the 'crq' if it is self
     signed and the signature is correct.  See 'gnutls_x509_crq_sign2()'
     .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_crq_extensions
----------------------------------

 -- Function: int gnutls_x509_crt_set_crq_extensions (gnutls_x509_crt_t
          CRT, gnutls_x509_crq_t CRQ)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     CRQ: holds a certificate request

     This function will set extensions from the given request to the
     certificate.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.8.0

gnutls_x509_crt_set_dn
----------------------

 -- Function: int gnutls_x509_crt_set_dn (gnutls_x509_crt_t CRT, const
          char * DN, const char ** ERR)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     DN: a comma separated DN string (RFC4514)

     ERR: indicates the error position (if any)

     This function will set the DN on the provided certificate.  The
     input string should be plain ASCII or UTF-8 encoded.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_dn_by_oid
-----------------------------

 -- Function: int gnutls_x509_crt_set_dn_by_oid (gnutls_x509_crt_t CRT,
          const char * OID, unsigned int RAW_FLAG, const void * NAME,
          unsigned int SIZEOF_NAME)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     OID: holds an Object Identifier in a null terminated string

     RAW_FLAG: must be 0, or 1 if the data are DER encoded

     NAME: a pointer to the name

     SIZEOF_NAME: holds the size of 'name'

     This function will set the part of the name of the Certificate
     subject, specified by the given OID. The input string should be
     ASCII or UTF-8 encoded.

     Some helper macros with popular OIDs can be found in gnutls/x509.h
     With this function you can only set the known OIDs.  You can test
     for known OIDs using 'gnutls_x509_dn_oid_known()' .  For OIDs that
     are not known (by gnutls) you should properly DER encode your data,
     and call this function with 'raw_flag' set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_expiration_time
-----------------------------------

 -- Function: int gnutls_x509_crt_set_expiration_time (gnutls_x509_crt_t
          CERT, time_t EXP_TIME)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     EXP_TIME: The actual time

     This function will set the time this Certificate will expire.
     Setting an expiration time to (time_t)-1 or to
     'GNUTLS_X509_NO_WELL_DEFINED_EXPIRATION' will set to the no
     well-defined expiration date value.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_extension_by_oid
------------------------------------

 -- Function: int gnutls_x509_crt_set_extension_by_oid
          (gnutls_x509_crt_t CRT, const char * OID, const void * BUF,
          size_t SIZEOF_BUF, unsigned int CRITICAL)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     OID: holds an Object Identified in null terminated string

     BUF: a pointer to a DER encoded data

     SIZEOF_BUF: holds the size of 'buf'

     CRITICAL: should be non-zero if the extension is to be marked as
     critical

     This function will set an the extension, by the specified OID, in
     the certificate.  The extension data should be binary data DER
     encoded.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_issuer_alt_name
-----------------------------------

 -- Function: int gnutls_x509_crt_set_issuer_alt_name (gnutls_x509_crt_t
          CRT, gnutls_x509_subject_alt_name_t TYPE, const void * DATA,
          unsigned int DATA_SIZE, unsigned int FLAGS)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     TYPE: is one of the gnutls_x509_subject_alt_name_t enumerations

     DATA: The data to be set

     DATA_SIZE: The size of data to be set

     FLAGS: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND
     to append.

     This function will set the issuer alternative name certificate
     extension.  It can set the same types as
     'gnutls_x509_crt_set_subject_alt_name()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_crt_set_issuer_dn
-----------------------------

 -- Function: int gnutls_x509_crt_set_issuer_dn (gnutls_x509_crt_t CRT,
          const char * DN, const char ** ERR)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     DN: a comma separated DN string (RFC4514)

     ERR: indicates the error position (if any)

     This function will set the DN on the provided certificate.  The
     input string should be plain ASCII or UTF-8 encoded.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_issuer_dn_by_oid
------------------------------------

 -- Function: int gnutls_x509_crt_set_issuer_dn_by_oid
          (gnutls_x509_crt_t CRT, const char * OID, unsigned int
          RAW_FLAG, const void * NAME, unsigned int SIZEOF_NAME)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     OID: holds an Object Identifier in a null terminated string

     RAW_FLAG: must be 0, or 1 if the data are DER encoded

     NAME: a pointer to the name

     SIZEOF_NAME: holds the size of 'name'

     This function will set the part of the name of the Certificate
     issuer, specified by the given OID. The input string should be
     ASCII or UTF-8 encoded.

     Some helper macros with popular OIDs can be found in gnutls/x509.h
     With this function you can only set the known OIDs.  You can test
     for known OIDs using 'gnutls_x509_dn_oid_known()' .  For OIDs that
     are not known (by gnutls) you should properly DER encode your data,
     and call this function with 'raw_flag' set.

     Normally you do not need to call this function, since the signing
     operation will copy the signer's name as the issuer of the
     certificate.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_issuer_unique_id
------------------------------------

 -- Function: int gnutls_x509_crt_set_issuer_unique_id
          (gnutls_x509_crt_t CERT, const void * ID, size_t ID_SIZE)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     ID: The unique ID

     ID_SIZE: Holds the size of the unique ID.

     This function will set the X.509 certificate's issuer unique ID
     field.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_key
-----------------------

 -- Function: int gnutls_x509_crt_set_key (gnutls_x509_crt_t CRT,
          gnutls_x509_privkey_t KEY)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     KEY: holds a private key

     This function will set the public parameters from the given private
     key to the certificate.  Only RSA keys are currently supported.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_key_purpose_oid
-----------------------------------

 -- Function: int gnutls_x509_crt_set_key_purpose_oid (gnutls_x509_crt_t
          CERT, const void * OID, unsigned int CRITICAL)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     OID: a pointer to a null terminated string that holds the OID

     CRITICAL: Whether this extension will be critical or not

     This function will set the key purpose OIDs of the Certificate.
     These are stored in the Extended Key Usage extension (2.5.29.37)
     See the GNUTLS_KP_* definitions for human readable names.

     Subsequent calls to this function will append OIDs to the OID list.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error code is returned.

gnutls_x509_crt_set_key_usage
-----------------------------

 -- Function: int gnutls_x509_crt_set_key_usage (gnutls_x509_crt_t CRT,
          unsigned int USAGE)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     USAGE: an ORed sequence of the GNUTLS_KEY_* elements.

     This function will set the keyUsage certificate extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_name_constraints
------------------------------------

 -- Function: int gnutls_x509_crt_set_name_constraints
          (gnutls_x509_crt_t CRT, gnutls_x509_name_constraints_t NC,
          unsigned int CRITICAL)
     CRT: The certificate structure

     NC: The nameconstraints structure

     CRITICAL: whether this extension will be critical

     This function will set the provided name constraints to the
     certificate extension list.  This extension is always marked as
     critical.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_crt_set_pin_function
--------------------------------

 -- Function: void gnutls_x509_crt_set_pin_function (gnutls_x509_crt_t
          CRT, gnutls_pin_callback_t FN, void * USERDATA)
     CRT: The certificate structure

     FN: the callback

     USERDATA: data associated with the callback

     This function will set a callback function to be used when it is
     required to access a protected object.  This function overrides the
     global function set using 'gnutls_pkcs11_set_pin_function()' .

     Note that this callback is currently used only during the import of
     a PKCS '11' certificate with 'gnutls_x509_crt_import_pkcs11_url()'
     .

     *Since:* 3.1.0

gnutls_x509_crt_set_policy
--------------------------

 -- Function: int gnutls_x509_crt_set_policy (gnutls_x509_crt_t CRT,
          const struct gnutls_x509_policy_st * POLICY, unsigned int
          CRITICAL)
     CRT: should contain a 'gnutls_x509_crt_t' structure

     POLICY: A pointer to a policy structure.

     CRITICAL: use non-zero if the extension is marked as critical

     This function will set the certificate policy extension
     (2.5.29.32).  Multiple calls to this function append a new policy.

     Note the maximum text size for the qualifier
     'GNUTLS_X509_QUALIFIER_NOTICE' is 200 characters.  This function
     will fail with 'GNUTLS_E_INVALID_REQUEST' if this is exceeded.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.1.5

gnutls_x509_crt_set_private_key_usage_period
--------------------------------------------

 -- Function: int gnutls_x509_crt_set_private_key_usage_period
          (gnutls_x509_crt_t CRT, time_t ACTIVATION, time_t EXPIRATION)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     ACTIVATION: The activation time

     EXPIRATION: The expiration time

     This function will set the private key usage period extension
     (2.5.29.16).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_proxy
-------------------------

 -- Function: int gnutls_x509_crt_set_proxy (gnutls_x509_crt_t CRT, int
          PATHLENCONSTRAINT, const char * POLICYLANGUAGE, const char *
          POLICY, size_t SIZEOF_POLICY)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     PATHLENCONSTRAINT: non-negative error codes indicate maximum length
     of path, and negative error codes indicate that the
     pathLenConstraints field should not be present.

     POLICYLANGUAGE: OID describing the language of 'policy' .

     POLICY: uint8_t byte array with policy language, can be 'NULL'

     SIZEOF_POLICY: size of 'policy' .

     This function will set the proxyCertInfo extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_proxy_dn
----------------------------

 -- Function: int gnutls_x509_crt_set_proxy_dn (gnutls_x509_crt_t CRT,
          gnutls_x509_crt_t EECRT, unsigned int RAW_FLAG, const void *
          NAME, unsigned int SIZEOF_NAME)
     CRT: a gnutls_x509_crt_t structure with the new proxy cert

     EECRT: the end entity certificate that will be issuing the proxy

     RAW_FLAG: must be 0, or 1 if the CN is DER encoded

     NAME: a pointer to the CN name, may be NULL (but MUST then be added
     later)

     SIZEOF_NAME: holds the size of 'name'

     This function will set the subject in 'crt' to the end entity's
     'eecrt' subject name, and add a single Common Name component 'name'
     of size 'sizeof_name' .  This corresponds to the required proxy
     certificate naming style.  Note that if 'name' is 'NULL' , you MUST
     set it later by using 'gnutls_x509_crt_set_dn_by_oid()' or similar.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_serial
--------------------------

 -- Function: int gnutls_x509_crt_set_serial (gnutls_x509_crt_t CERT,
          const void * SERIAL, size_t SERIAL_SIZE)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     SERIAL: The serial number

     SERIAL_SIZE: Holds the size of the serial field.

     This function will set the X.509 certificate's serial number.
     While the serial number is an integer, it is often handled as an
     opaque field by several CAs.  For this reason this function accepts
     any kind of data as a serial number.  To be consistent with the
     X.509/PKIX specifications the provided 'serial' should be a
     big-endian positive number (i.e.  it's leftmost bit should be
     zero).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_subject_alt_name
------------------------------------

 -- Function: int gnutls_x509_crt_set_subject_alt_name
          (gnutls_x509_crt_t CRT, gnutls_x509_subject_alt_name_t TYPE,
          const void * DATA, unsigned int DATA_SIZE, unsigned int FLAGS)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     TYPE: is one of the gnutls_x509_subject_alt_name_t enumerations

     DATA: The data to be set

     DATA_SIZE: The size of data to be set

     FLAGS: GNUTLS_FSAN_SET to clear previous data or GNUTLS_FSAN_APPEND
     to append.

     This function will set the subject alternative name certificate
     extension.  It can set the following types:

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.6.0

gnutls_x509_crt_set_subject_alternative_name
--------------------------------------------

 -- Function: int gnutls_x509_crt_set_subject_alternative_name
          (gnutls_x509_crt_t CRT, gnutls_x509_subject_alt_name_t TYPE,
          const char * DATA_STRING)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     TYPE: is one of the gnutls_x509_subject_alt_name_t enumerations

     DATA_STRING: The data to be set, a (0) terminated string

     This function will set the subject alternative name certificate
     extension.  This function assumes that data can be expressed as a
     null terminated string.

     The name of the function is unfortunate since it is incosistent
     with 'gnutls_x509_crt_get_subject_alt_name()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_subject_key_id
----------------------------------

 -- Function: int gnutls_x509_crt_set_subject_key_id (gnutls_x509_crt_t
          CERT, const void * ID, size_t ID_SIZE)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     ID: The key ID

     ID_SIZE: Holds the size of the subject key ID field.

     This function will set the X.509 certificate's subject key ID
     extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_subject_unique_id
-------------------------------------

 -- Function: int gnutls_x509_crt_set_subject_unique_id
          (gnutls_x509_crt_t CERT, const void * ID, size_t ID_SIZE)
     CERT: a certificate of type 'gnutls_x509_crt_t'

     ID: The unique ID

     ID_SIZE: Holds the size of the unique ID.

     This function will set the X.509 certificate's subject unique ID
     field.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_set_version
---------------------------

 -- Function: int gnutls_x509_crt_set_version (gnutls_x509_crt_t CRT,
          unsigned int VERSION)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     VERSION: holds the version number.  For X.509v1 certificates must
     be 1.

     This function will set the version of the certificate.  This must
     be one for X.509 version 1, and so on.  Plain certificates without
     extensions must have version set to one.

     To create well-formed certificates, you must specify version 3 if
     you use any certificate extensions.  Extensions are created by
     functions such as 'gnutls_x509_crt_set_subject_alt_name()' or
     'gnutls_x509_crt_set_key_usage()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_sign
--------------------

 -- Function: int gnutls_x509_crt_sign (gnutls_x509_crt_t CRT,
          gnutls_x509_crt_t ISSUER, gnutls_x509_privkey_t ISSUER_KEY)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     ISSUER: is the certificate of the certificate issuer

     ISSUER_KEY: holds the issuer's private key

     This function is the same a 'gnutls_x509_crt_sign2()' with no
     flags, and SHA1 as the hash algorithm.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_sign2
---------------------

 -- Function: int gnutls_x509_crt_sign2 (gnutls_x509_crt_t CRT,
          gnutls_x509_crt_t ISSUER, gnutls_x509_privkey_t ISSUER_KEY,
          gnutls_digest_algorithm_t DIG, unsigned int FLAGS)
     CRT: a certificate of type 'gnutls_x509_crt_t'

     ISSUER: is the certificate of the certificate issuer

     ISSUER_KEY: holds the issuer's private key

     DIG: The message digest to use, 'GNUTLS_DIG_SHA1' is a safe choice

     FLAGS: must be 0

     This function will sign the certificate with the issuer's private
     key, and will copy the issuer's information into the certificate.

     This must be the last step in a certificate generation since all
     the previously set parameters are now signed.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_crt_verify
----------------------

 -- Function: int gnutls_x509_crt_verify (gnutls_x509_crt_t CERT, const
          gnutls_x509_crt_t * CA_LIST, int CA_LIST_LENGTH, unsigned int
          FLAGS, unsigned int * VERIFY)
     CERT: is the certificate to be verified

     CA_LIST: is one certificate that is considered to be trusted one

     CA_LIST_LENGTH: holds the number of CA certificate in CA_list

     FLAGS: Flags that may be used to change the verification algorithm.
     Use OR of the gnutls_certificate_verify_flags enumerations.

     VERIFY: will hold the certificate verification output.

     This function will try to verify the given certificate and return
     its status.  Note that a verification error does not imply a
     negative return status.  In that case the 'verify' status is set.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_dn_deinit
---------------------

 -- Function: void gnutls_x509_dn_deinit (gnutls_x509_dn_t DN)
     DN: a DN uint8_t object pointer.

     This function deallocates the DN object as returned by
     'gnutls_x509_dn_import()' .

     *Since:* 2.4.0

gnutls_x509_dn_export
---------------------

 -- Function: int gnutls_x509_dn_export (gnutls_x509_dn_t DN,
          gnutls_x509_crt_fmt_t FORMAT, void * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     DN: Holds the uint8_t DN object

     FORMAT: the format of output params.  One of PEM or DER.

     OUTPUT_DATA: will contain a DN PEM or DER encoded

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will export the DN to DER or PEM format.

     If the buffer provided is not long enough to hold the output, then
     * 'output_data_size' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER'
     will be returned.

     If the structure is PEM encoded, it will have a header of "BEGIN
     NAME".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_dn_export2
----------------------

 -- Function: int gnutls_x509_dn_export2 (gnutls_x509_dn_t DN,
          gnutls_x509_crt_fmt_t FORMAT, gnutls_datum_t * OUT)
     DN: Holds the uint8_t DN object

     FORMAT: the format of output params.  One of PEM or DER.

     OUT: will contain a DN PEM or DER encoded

     This function will export the DN to DER or PEM format.

     The output buffer is allocated using 'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN
     NAME".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.1.3

gnutls_x509_dn_get_rdn_ava
--------------------------

 -- Function: int gnutls_x509_dn_get_rdn_ava (gnutls_x509_dn_t DN, int
          IRDN, int IAVA, gnutls_x509_ava_st * AVA)
     DN: a pointer to DN

     IRDN: index of RDN

     IAVA: index of AVA.

     AVA: Pointer to structure which will hold output information.

     Get pointers to data within the DN. The format of the 'ava'
     structure is shown below.

     struct gnutls_x509_ava_st { gnutls_datum_t oid; gnutls_datum_t
     value; unsigned long value_tag; };

     The X.509 distinguished name is a sequence of sequences of strings
     and this is what the 'irdn' and 'iava' indexes model.

     Note that 'ava' will contain pointers into the 'dn' structure which
     in turns points to the original certificate.  Thus you should not
     modify any data or deallocate any of those.

     This is a low-level function that requires the caller to do the
     value conversions when necessary (e.g.  from UCS-2).

     *Returns:* Returns 0 on success, or an error code.

gnutls_x509_dn_import
---------------------

 -- Function: int gnutls_x509_dn_import (gnutls_x509_dn_t DN, const
          gnutls_datum_t * DATA)
     DN: the structure that will hold the imported DN

     DATA: should contain a DER encoded RDN sequence

     This function parses an RDN sequence and stores the result to a
     'gnutls_x509_dn_t' structure.  The structure must have been
     initialized with 'gnutls_x509_dn_init()' .  You may use
     'gnutls_x509_dn_get_rdn_ava()' to decode the DN.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.4.0

gnutls_x509_dn_init
-------------------

 -- Function: int gnutls_x509_dn_init (gnutls_x509_dn_t * DN)
     DN: the object to be initialized

     This function initializes a 'gnutls_x509_dn_t' structure.

     The object returned must be deallocated using
     'gnutls_x509_dn_deinit()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.4.0

gnutls_x509_dn_oid_known
------------------------

 -- Function: int gnutls_x509_dn_oid_known (const char * OID)
     OID: holds an Object Identifier in a null terminated string

     This function will inform about known DN OIDs.  This is useful
     since functions like 'gnutls_x509_crt_set_dn_by_oid()' use the
     information on known OIDs to properly encode their input.  Object
     Identifiers that are not known are not encoded by these functions,
     and their input is stored directly into the ASN.1 structure.  In
     that case of unknown OIDs, you have the responsibility of DER
     encoding your data.

     *Returns:* 1 on known OIDs and 0 otherwise.

gnutls_x509_dn_oid_name
-----------------------

 -- Function: const char * gnutls_x509_dn_oid_name (const char * OID,
          unsigned int FLAGS)
     OID: holds an Object Identifier in a null terminated string

     FLAGS: 0 or GNUTLS_X509_DN_OID_*

     This function will return the name of a known DN OID. If
     'GNUTLS_X509_DN_OID_RETURN_OID' is specified this function will
     return the given OID if no descriptive name has been found.

     *Returns:* A null terminated string or NULL otherwise.

     *Since:* 3.0

gnutls_x509_ext_deinit
----------------------

 -- Function: void gnutls_x509_ext_deinit (gnutls_x509_ext_st * EXT)
     EXT: The extensions structure

     This function will deinitialize an extensions structure.

     *Since:* 3.3.8

gnutls_x509_ext_export_aia
--------------------------

 -- Function: int gnutls_x509_ext_export_aia (gnutls_x509_aia_t AIA,
          gnutls_datum_t * EXT)
     AIA: The authority info access structure

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will DER encode the Authority Information Access
     (AIA) extension; see RFC 5280 section 4.2.2.1 for more information
     on the extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_authority_key_id
---------------------------------------

 -- Function: int gnutls_x509_ext_export_authority_key_id
          (gnutls_x509_aki_t AKI, gnutls_datum_t * EXT)
     AKI: An initialized authority key identifier structure

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the provided key identifier to a
     DER-encoded PKIX AuthorityKeyIdentifier extension.  The output data
     in 'ext' will be allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_basic_constraints
----------------------------------------

 -- Function: int gnutls_x509_ext_export_basic_constraints (unsigned int
          CA, int PATHLEN, gnutls_datum_t * EXT)
     CA: non-zero for a CA

     PATHLEN: The path length constraint (set to -1 for no constraint)

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the parameters provided to a basic
     constraints DER encoded extension (2.5.29.19).  The 'ext' data will
     be allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_crl_dist_points
--------------------------------------

 -- Function: int gnutls_x509_ext_export_crl_dist_points
          (gnutls_x509_crl_dist_points_t CDP, gnutls_datum_t * EXT)
     CDP: A pointer to an initialized CRL distribution points structure.

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the provided policies, to a certificate
     policy DER encoded extension (2.5.29.31).

     The 'ext' data will be allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_key_purposes
-----------------------------------

 -- Function: int gnutls_x509_ext_export_key_purposes
          (gnutls_x509_key_purposes_t P, gnutls_datum_t * EXT)
     P: The key purposes structure

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the key purposes structure to a
     DER-encoded PKIX ExtKeyUsageSyntax (2.5.29.37) extension.  The
     output data in 'ext' will be allocated usin 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_key_usage
--------------------------------

 -- Function: int gnutls_x509_ext_export_key_usage (unsigned int USAGE,
          gnutls_datum_t * EXT)
     USAGE: an ORed sequence of the GNUTLS_KEY_* elements.

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the keyUsage bit string to a DER encoded
     PKIX extension.  The 'ext' data will be allocated using
     'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_name_constraints
---------------------------------------

 -- Function: int gnutls_x509_ext_export_name_constraints
          (gnutls_x509_name_constraints_t NC, gnutls_datum_t * EXT)
     NC: The nameconstraints structure

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the provided name constraints structure
     to a DER-encoded PKIX NameConstraints (2.5.29.30) extension.  The
     output data in 'ext' will be allocated usin 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_policies
-------------------------------

 -- Function: int gnutls_x509_ext_export_policies
          (gnutls_x509_policies_t POLICIES, gnutls_datum_t * EXT)
     POLICIES: A pointer to an initialized policies structure.

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the provided policies, to a certificate
     policy DER encoded extension (2.5.29.32).

     The 'ext' data will be allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_private_key_usage_period
-----------------------------------------------

 -- Function: int gnutls_x509_ext_export_private_key_usage_period
          (time_t ACTIVATION, time_t EXPIRATION, gnutls_datum_t * EXT)
     ACTIVATION: The activation time

     EXPIRATION: The expiration time

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the periods provided to a private key
     usage DER encoded extension (2.5.29.16).  The 'ext' data will be
     allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_proxy
----------------------------

 -- Function: int gnutls_x509_ext_export_proxy (int PATHLENCONSTRAINT,
          const char * POLICYLANGUAGE, const char * POLICY, size_t
          SIZEOF_POLICY, gnutls_datum_t * EXT)
     PATHLENCONSTRAINT: non-negative error codes indicate maximum length
     of path, and negative error codes indicate that the
     pathLenConstraints field should not be present.

     POLICYLANGUAGE: OID describing the language of 'policy' .

     POLICY: uint8_t byte array with policy language, can be 'NULL'

     SIZEOF_POLICY: size of 'policy' .

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the parameters provided to a
     proxyCertInfo extension.

     The 'ext' data will be allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_subject_alt_names
----------------------------------------

 -- Function: int gnutls_x509_ext_export_subject_alt_names
          (gnutls_subject_alt_names_t SANS, gnutls_datum_t * EXT)
     SANS: The alternative names structure

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the provided alternative names structure
     to a DER-encoded SubjectAltName PKIX extension.  The output data in
     'ext' will be allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_export_subject_key_id
-------------------------------------

 -- Function: int gnutls_x509_ext_export_subject_key_id (const
          gnutls_datum_t * ID, gnutls_datum_t * EXT)
     ID: The key identifier

     EXT: The DER-encoded extension data; must be freed using
     'gnutls_free()' .

     This function will convert the provided key identifier to a
     DER-encoded PKIX SubjectKeyIdentifier extension.  The output data
     in 'ext' will be allocated using 'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_aia
--------------------------

 -- Function: int gnutls_x509_ext_import_aia (const gnutls_datum_t *
          EXT, gnutls_x509_aia_t AIA, unsigned int FLAGS)
     EXT: The DER-encoded extension data

     AIA: The authority info access structure

     FLAGS: should be zero

     This function extracts the Authority Information Access (AIA)
     extension from the provided DER-encoded data; see RFC 5280 section
     4.2.2.1 for more information on the extension.  The AIA extension
     holds a sequence of AccessDescription (AD) data.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_authority_key_id
---------------------------------------

 -- Function: int gnutls_x509_ext_import_authority_key_id (const
          gnutls_datum_t * EXT, gnutls_x509_aki_t AKI, unsigned int
          FLAGS)
     EXT: a DER encoded extension

     AKI: An initialized authority key identifier structure

     FLAGS: should be zero

     This function will return the subject key ID stored in the provided
     AuthorityKeyIdentifier extension.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_basic_constraints
----------------------------------------

 -- Function: int gnutls_x509_ext_import_basic_constraints (const
          gnutls_datum_t * EXT, unsigned int * CA, int * PATHLEN)
     EXT: the DER encoded extension data

     CA: will be non zero if the CA status is true

     PATHLEN: the path length constraint; will be set to -1 for no limit

     This function will return the CA status and path length constraint
     as written in the PKIX extension 2.5.29.19.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_crl_dist_points
--------------------------------------

 -- Function: int gnutls_x509_ext_import_crl_dist_points (const
          gnutls_datum_t * EXT, gnutls_x509_crl_dist_points_t CDP,
          unsigned int FLAGS)
     EXT: the DER encoded extension data

     CDP: A pointer to an initialized CRL distribution points structure.

     FLAGS: should be zero

     This function will extract the CRL distribution points extension
     (2.5.29.31) and store it into the provided structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_key_purposes
-----------------------------------

 -- Function: int gnutls_x509_ext_import_key_purposes (const
          gnutls_datum_t * EXT, gnutls_x509_key_purposes_t P, unsigned
          int FLAGS)
     EXT: The DER-encoded extension data

     P: The key purposes structure

     FLAGS: should be zero

     This function will extract the key purposes in the provided
     DER-encoded ExtKeyUsageSyntax PKIX extension, to a
     'gnutls_x509_key_purposes_t' structure.  The structure must be
     initialized.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_key_usage
--------------------------------

 -- Function: int gnutls_x509_ext_import_key_usage (const gnutls_datum_t
          * EXT, unsigned int * KEY_USAGE)
     EXT: the DER encoded extension data

     KEY_USAGE: where the key usage bits will be stored

     This function will return certificate's key usage, by reading the
     DER data of the keyUsage X.509 extension (2.5.29.15).  The key
     usage value will ORed values of the: 'GNUTLS_KEY_DIGITAL_SIGNATURE'
     , 'GNUTLS_KEY_NON_REPUDIATION' , 'GNUTLS_KEY_KEY_ENCIPHERMENT' ,
     'GNUTLS_KEY_DATA_ENCIPHERMENT' , 'GNUTLS_KEY_KEY_AGREEMENT' ,
     'GNUTLS_KEY_KEY_CERT_SIGN' , 'GNUTLS_KEY_CRL_SIGN' ,
     'GNUTLS_KEY_ENCIPHER_ONLY' , 'GNUTLS_KEY_DECIPHER_ONLY' .

     *Returns:* the certificate key usage, or a negative error code in
     case of parsing error.  If the certificate does not contain the
     keyUsage extension 'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' will be
     returned.

     *Since:* 3.3.0

gnutls_x509_ext_import_name_constraints
---------------------------------------

 -- Function: int gnutls_x509_ext_import_name_constraints (const
          gnutls_datum_t * EXT, gnutls_x509_name_constraints_t NC,
          unsigned int FLAGS)
     EXT: a DER encoded extension

     NC: The nameconstraints intermediate structure

     FLAGS: zero or 'GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND'

     This function will return an intermediate structure containing the
     name constraints of the provided NameConstraints extension.  That
     structure can be used in combination with
     'gnutls_x509_name_constraints_check()' to verify whether a server's
     name is in accordance with the constraints.

     When the 'flags' is set to 'GNUTLS_NAME_CONSTRAINTS_FLAG_APPEND' ,
     then if the 'nc' structure is empty this function will behave
     identically as if the flag was not set.  Otherwise if there are
     elements in the 'nc' structure then only the excluded constraints
     will be appended to the constraints.

     Note that 'nc' must be initialized prior to calling this function.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_policies
-------------------------------

 -- Function: int gnutls_x509_ext_import_policies (const gnutls_datum_t
          * EXT, gnutls_x509_policies_t POLICIES, unsigned int FLAGS)
     EXT: the DER encoded extension data

     POLICIES: A pointer to an initialized policies structures.

     FLAGS: should be zero

     This function will extract the certificate policy extension
     (2.5.29.32) and store it the provided structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_private_key_usage_period
-----------------------------------------------

 -- Function: int gnutls_x509_ext_import_private_key_usage_period (const
          gnutls_datum_t * EXT, time_t * ACTIVATION, time_t *
          EXPIRATION)
     EXT: the DER encoded extension data

     ACTIVATION: Will hold the activation time

     EXPIRATION: Will hold the expiration time

     This function will return the expiration and activation times of
     the private key as written in the PKIX extension 2.5.29.16.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_proxy
----------------------------

 -- Function: int gnutls_x509_ext_import_proxy (const gnutls_datum_t *
          EXT, int * PATHLEN, char ** POLICYLANGUAGE, char ** POLICY,
          size_t * SIZEOF_POLICY)
     EXT: the DER encoded extension data

     PATHLEN: pointer to output integer indicating path length (may be
     NULL), non-negative error codes indicate a present
     pCPathLenConstraint field and the actual value, -1 indicate that
     the field is absent.

     POLICYLANGUAGE: output variable with OID of policy language

     POLICY: output variable with policy data

     SIZEOF_POLICY: output variable size of policy data

     This function will return the information from a proxy certificate
     extension.  It reads the ProxyCertInfo X.509 extension
     (1.3.6.1.5.5.7.1.14).  The 'policyLanguage' and 'policy' values
     must be deinitialized using 'gnutls_free()' after use.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_subject_alt_names
----------------------------------------

 -- Function: int gnutls_x509_ext_import_subject_alt_names (const
          gnutls_datum_t * EXT, gnutls_subject_alt_names_t SANS,
          unsigned int FLAGS)
     EXT: The DER-encoded extension data

     SANS: The alternative names structure

     FLAGS: should be zero

     This function will export the alternative names in the provided
     DER-encoded SubjectAltName PKIX extension, to a
     'gnutls_subject_alt_names_t' structure.  The structure must have
     been initialized.

     This function will succeed even if there no subject alternative
     names in the structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_import_subject_key_id
-------------------------------------

 -- Function: int gnutls_x509_ext_import_subject_key_id (const
          gnutls_datum_t * EXT, gnutls_datum_t * ID)
     EXT: a DER encoded extension

     ID: will contain the subject key ID

     This function will return the subject key ID stored in the provided
     SubjectKeyIdentifier extension.  The ID will be allocated using
     'gnutls_malloc()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_ext_print
---------------------

 -- Function: int gnutls_x509_ext_print (gnutls_x509_ext_st * EXTS,
          unsigned int EXTS_SIZE, gnutls_certificate_print_formats_t
          FORMAT, gnutls_datum_t * OUT)
     EXTS: The structures to be printed

     EXTS_SIZE: the number of available structures

     FORMAT: Indicate the format to use

     OUT: Newly allocated datum with null terminated string.

     This function will pretty print X.509 certificate extensions,
     suitable for display to a human.

     The output 'out' needs to be deallocated using 'gnutls_free()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_key_purpose_deinit
------------------------------

 -- Function: void gnutls_x509_key_purpose_deinit
          (gnutls_x509_key_purposes_t P)
     P: The key purposes structure

     This function will deinitialize an alternative names structure.

     *Since:* 3.3.0

gnutls_x509_key_purpose_get
---------------------------

 -- Function: int gnutls_x509_key_purpose_get
          (gnutls_x509_key_purposes_t P, unsigned IDX, gnutls_datum_t *
          OID)
     P: The key purposes structure

     IDX: The index of the key purpose to retrieve

     OID: Will hold the object identifier of the key purpose (to be
     treated as constant)

     This function will retrieve the specified by the index key purpose
     in the purposes structure.  The object identifier will be a null
     terminated string.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the index is out of
     bounds, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_key_purpose_init
----------------------------

 -- Function: int gnutls_x509_key_purpose_init
          (gnutls_x509_key_purposes_t * P)
     P: The key purposes structure

     This function will initialize an alternative names structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_key_purpose_set
---------------------------

 -- Function: int gnutls_x509_key_purpose_set
          (gnutls_x509_key_purposes_t P, const char * OID)
     P: The key purposes structure

     OID: The object identifier of the key purpose

     This function will store the specified key purpose in the purposes
     structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0), otherwise a negative
     error value.

     *Since:* 3.3.0

gnutls_x509_name_constraints_add_excluded
-----------------------------------------

 -- Function: int gnutls_x509_name_constraints_add_excluded
          (gnutls_x509_name_constraints_t NC,
          gnutls_x509_subject_alt_name_t TYPE, const gnutls_datum_t *
          NAME)
     NC: The nameconstraints structure

     TYPE: The type of the constraints

     NAME: The data of the constraints

     This function will add a name constraint to the list of excluded
     constraints.  The constraints 'type' can be any of the following
     types: 'GNUTLS_SAN_DNSNAME' , 'GNUTLS_SAN_RFC822NAME' ,
     'GNUTLS_SAN_DN' , 'GNUTLS_SAN_URI' , 'GNUTLS_SAN_IPADDRESS' .  For
     the latter, an IP address in network byte order is expected,
     followed by its network mask (which is 4 bytes in IPv4 or 16-bytes
     in IPv6).

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_name_constraints_add_permitted
------------------------------------------

 -- Function: int gnutls_x509_name_constraints_add_permitted
          (gnutls_x509_name_constraints_t NC,
          gnutls_x509_subject_alt_name_t TYPE, const gnutls_datum_t *
          NAME)
     NC: The nameconstraints structure

     TYPE: The type of the constraints

     NAME: The data of the constraints

     This function will add a name constraint to the list of permitted
     constraints.  The constraints 'type' can be any of the following
     types: 'GNUTLS_SAN_DNSNAME' , 'GNUTLS_SAN_RFC822NAME' ,
     'GNUTLS_SAN_DN' , 'GNUTLS_SAN_URI' , 'GNUTLS_SAN_IPADDRESS' .  For
     the latter, an IP address in network byte order is expected,
     followed by its network mask.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_name_constraints_check
----------------------------------

 -- Function: unsigned gnutls_x509_name_constraints_check
          (gnutls_x509_name_constraints_t NC,
          gnutls_x509_subject_alt_name_t TYPE, const gnutls_datum_t *
          NAME)
     NC: the extracted name constraints structure

     TYPE: the type of the constraint to check (of type
     gnutls_x509_subject_alt_name_t)

     NAME: the name to be checked

     This function will check the provided name against the constraints
     in 'nc' using the RFC5280 rules.  Currently this function is
     limited to DNS names and emails (of type 'GNUTLS_SAN_DNSNAME' and
     'GNUTLS_SAN_RFC822NAME' ).

     *Returns:* zero if the provided name is not acceptable, and
     non-zero otherwise.

     *Since:* 3.3.0

gnutls_x509_name_constraints_check_crt
--------------------------------------

 -- Function: unsigned gnutls_x509_name_constraints_check_crt
          (gnutls_x509_name_constraints_t NC,
          gnutls_x509_subject_alt_name_t TYPE, gnutls_x509_crt_t CERT)
     NC: the extracted name constraints structure

     TYPE: the type of the constraint to check (of type
     gnutls_x509_subject_alt_name_t)

     CERT: the certificate to be checked

     This function will check the provided certificate names against the
     constraints in 'nc' using the RFC5280 rules.  It will traverse all
     the certificate's names and alternative names.

     Currently this function is limited to DNS names and emails (of type
     'GNUTLS_SAN_DNSNAME' and 'GNUTLS_SAN_RFC822NAME' ).

     *Returns:* zero if the provided name is not acceptable, and
     non-zero otherwise.

     *Since:* 3.3.0

gnutls_x509_name_constraints_deinit
-----------------------------------

 -- Function: void gnutls_x509_name_constraints_deinit
          (gnutls_x509_name_constraints_t NC)
     NC: The nameconstraints structure

     This function will deinitialize a name constraints structure.

     *Since:* 3.3.0

gnutls_x509_name_constraints_get_excluded
-----------------------------------------

 -- Function: int gnutls_x509_name_constraints_get_excluded
          (gnutls_x509_name_constraints_t NC, unsigned IDX, unsigned *
          TYPE, gnutls_datum_t * NAME)
     NC: the extracted name constraints structure

     IDX: the index of the constraint

     TYPE: the type of the constraint (of type
     gnutls_x509_subject_alt_name_t)

     NAME: the name in the constraint (of the specific type)

     This function will return an intermediate structure containing the
     name constraints of the provided CA certificate.  That structure
     can be used in combination with
     'gnutls_x509_name_constraints_check()' to verify whether a server's
     name is in accordance with the constraints.

     The name should be treated as constant and valid for the lifetime
     of 'nc' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_name_constraints_get_permitted
------------------------------------------

 -- Function: int gnutls_x509_name_constraints_get_permitted
          (gnutls_x509_name_constraints_t NC, unsigned IDX, unsigned *
          TYPE, gnutls_datum_t * NAME)
     NC: the extracted name constraints structure

     IDX: the index of the constraint

     TYPE: the type of the constraint (of type
     gnutls_x509_subject_alt_name_t)

     NAME: the name in the constraint (of the specific type)

     This function will return an intermediate structure containing the
     name constraints of the provided CA certificate.  That structure
     can be used in combination with
     'gnutls_x509_name_constraints_check()' to verify whether a server's
     name is in accordance with the constraints.

     The name should be treated as constant and valid for the lifetime
     of 'nc' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the extension is not
     present, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_name_constraints_init
---------------------------------

 -- Function: int gnutls_x509_name_constraints_init
          (gnutls_x509_name_constraints_t * NC)
     NC: The nameconstraints structure

     This function will initialize a name constraints structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_othername_to_virtual
--------------------------------

 -- Function: int gnutls_x509_othername_to_virtual (const char * OID,
          const gnutls_datum_t * OTHERNAME, unsigned int * VIRT_TYPE,
          gnutls_datum_t * VIRT)
     OID: The othername object identifier

     OTHERNAME: - undescribed -

     VIRT_TYPE: GNUTLS_SAN_OTHERNAME_XXX

     VIRT: allocated printable data

     This function will parse and convert the othername data to a
     virtual type supported by gnutls.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.8

gnutls_x509_policies_deinit
---------------------------

 -- Function: void gnutls_x509_policies_deinit (gnutls_x509_policies_t
          POLICIES)
     POLICIES: The authority key identifier structure

     This function will deinitialize an authority key identifier
     structure.

     *Since:* 3.3.0

gnutls_x509_policies_get
------------------------

 -- Function: int gnutls_x509_policies_get (gnutls_x509_policies_t
          POLICIES, unsigned int SEQ, struct gnutls_x509_policy_st *
          POLICY)
     POLICIES: The policies structure

     SEQ: The index of the name to get

     POLICY: Will hold the policy

     This function will return a specific policy as stored in the
     'policies' structure.  The returned values should be treated as
     constant and valid for the lifetime of 'policies' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     'GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE' if the index is out of
     bounds, otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_policies_init
-------------------------

 -- Function: int gnutls_x509_policies_init (gnutls_x509_policies_t *
          POLICIES)
     POLICIES: The authority key ID structure

     This function will initialize an authority key ID structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.3.0

gnutls_x509_policies_set
------------------------

 -- Function: int gnutls_x509_policies_set (gnutls_x509_policies_t
          POLICIES, const struct gnutls_x509_policy_st * POLICY)
     POLICIES: An initialized policies structure

     POLICY: Contains the policy to set

     This function will store the specified policy in the provided
     'policies' structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0), otherwise a negative
     error value.

     *Since:* 3.3.0

gnutls_x509_policy_release
--------------------------

 -- Function: void gnutls_x509_policy_release (struct
          gnutls_x509_policy_st * POLICY)
     POLICY: a certificate policy

     This function will deinitialize all memory associated with the
     provided 'policy' .  The policy is allocated using
     'gnutls_x509_crt_get_policy()' .

     *Since:* 3.1.5

gnutls_x509_privkey_cpy
-----------------------

 -- Function: int gnutls_x509_privkey_cpy (gnutls_x509_privkey_t DST,
          gnutls_x509_privkey_t SRC)
     DST: The destination key, which should be initialized.

     SRC: The source key

     This function will copy a private key from source to destination
     key.  Destination has to be initialized.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_deinit
--------------------------

 -- Function: void gnutls_x509_privkey_deinit (gnutls_x509_privkey_t
          KEY)
     KEY: The structure to be deinitialized

     This function will deinitialize a private key structure.

gnutls_x509_privkey_export
--------------------------

 -- Function: int gnutls_x509_privkey_export (gnutls_x509_privkey_t KEY,
          gnutls_x509_crt_fmt_t FORMAT, void * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     KEY: Holds the key

     FORMAT: the format of output params.  One of PEM or DER.

     OUTPUT_DATA: will contain a private key PEM or DER encoded

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will export the private key to a PKCS1 structure for
     RSA keys, or an integer sequence for DSA keys.  The DSA keys are in
     the same format with the parameters used by openssl.

     If the buffer provided is not long enough to hold the output, then
     * 'output_data_size' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER'
     will be returned.

     If the structure is PEM encoded, it will have a header of "BEGIN
     RSA PRIVATE KEY".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_export2
---------------------------

 -- Function: int gnutls_x509_privkey_export2 (gnutls_x509_privkey_t
          KEY, gnutls_x509_crt_fmt_t FORMAT, gnutls_datum_t * OUT)
     KEY: Holds the key

     FORMAT: the format of output params.  One of PEM or DER.

     OUT: will contain a private key PEM or DER encoded

     This function will export the private key to a PKCS1 structure for
     RSA keys, or an integer sequence for DSA keys.  The DSA keys are in
     the same format with the parameters used by openssl.

     The output buffer is allocated using 'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN
     RSA PRIVATE KEY".

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     Since 3.1.3

gnutls_x509_privkey_export2_pkcs8
---------------------------------

 -- Function: int gnutls_x509_privkey_export2_pkcs8
          (gnutls_x509_privkey_t KEY, gnutls_x509_crt_fmt_t FORMAT,
          const char * PASSWORD, unsigned int FLAGS, gnutls_datum_t *
          OUT)
     KEY: Holds the key

     FORMAT: the format of output params.  One of PEM or DER.

     PASSWORD: the password that will be used to encrypt the key.

     FLAGS: an ORed sequence of gnutls_pkcs_encrypt_flags_t

     OUT: will contain a private key PEM or DER encoded

     This function will export the private key to a PKCS8 structure.
     Both RSA and DSA keys can be exported.  For DSA keys we use PKCS
     '11' definitions.  If the flags do not specify the encryption
     cipher, then the default 3DES (PBES2) will be used.

     The 'password' can be either ASCII or UTF-8 in the default PBES2
     encryption schemas, or ASCII for the PKCS12 schemas.

     The output buffer is allocated using 'gnutls_malloc()' .

     If the structure is PEM encoded, it will have a header of "BEGIN
     ENCRYPTED PRIVATE KEY" or "BEGIN PRIVATE KEY" if encryption is not
     used.

     *Returns:* In case of failure a negative error code will be
     returned, and 0 on success.

     Since 3.1.3

gnutls_x509_privkey_export_dsa_raw
----------------------------------

 -- Function: int gnutls_x509_privkey_export_dsa_raw
          (gnutls_x509_privkey_t KEY, gnutls_datum_t * P, gnutls_datum_t
          * Q, gnutls_datum_t * G, gnutls_datum_t * Y, gnutls_datum_t *
          X)
     KEY: a structure that holds the DSA parameters

     P: will hold the p

     Q: will hold the q

     G: will hold the g

     Y: will hold the y

     X: will hold the x

     This function will export the DSA private key's parameters found in
     the given structure.  The new parameters will be allocated using
     'gnutls_malloc()' and will be stored in the appropriate datum.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_export_ecc_raw
----------------------------------

 -- Function: int gnutls_x509_privkey_export_ecc_raw
          (gnutls_x509_privkey_t KEY, gnutls_ecc_curve_t * CURVE,
          gnutls_datum_t * X, gnutls_datum_t * Y, gnutls_datum_t * K)
     KEY: a structure that holds the rsa parameters

     CURVE: will hold the curve

     X: will hold the x coordinate

     Y: will hold the y coordinate

     K: will hold the private key

     This function will export the ECC private key's parameters found in
     the given structure.  The new parameters will be allocated using
     'gnutls_malloc()' and will be stored in the appropriate datum.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0

gnutls_x509_privkey_export_pkcs8
--------------------------------

 -- Function: int gnutls_x509_privkey_export_pkcs8
          (gnutls_x509_privkey_t KEY, gnutls_x509_crt_fmt_t FORMAT,
          const char * PASSWORD, unsigned int FLAGS, void * OUTPUT_DATA,
          size_t * OUTPUT_DATA_SIZE)
     KEY: Holds the key

     FORMAT: the format of output params.  One of PEM or DER.

     PASSWORD: the password that will be used to encrypt the key.

     FLAGS: an ORed sequence of gnutls_pkcs_encrypt_flags_t

     OUTPUT_DATA: will contain a private key PEM or DER encoded

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will export the private key to a PKCS8 structure.
     Both RSA and DSA keys can be exported.  For DSA keys we use PKCS
     '11' definitions.  If the flags do not specify the encryption
     cipher, then the default 3DES (PBES2) will be used.

     The 'password' can be either ASCII or UTF-8 in the default PBES2
     encryption schemas, or ASCII for the PKCS12 schemas.

     If the buffer provided is not long enough to hold the output, then
     *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
     be returned.

     If the structure is PEM encoded, it will have a header of "BEGIN
     ENCRYPTED PRIVATE KEY" or "BEGIN PRIVATE KEY" if encryption is not
     used.

     *Returns:* In case of failure a negative error code will be
     returned, and 0 on success.

gnutls_x509_privkey_export_rsa_raw
----------------------------------

 -- Function: int gnutls_x509_privkey_export_rsa_raw
          (gnutls_x509_privkey_t KEY, gnutls_datum_t * M, gnutls_datum_t
          * E, gnutls_datum_t * D, gnutls_datum_t * P, gnutls_datum_t *
          Q, gnutls_datum_t * U)
     KEY: a structure that holds the rsa parameters

     M: will hold the modulus

     E: will hold the public exponent

     D: will hold the private exponent

     P: will hold the first prime (p)

     Q: will hold the second prime (q)

     U: will hold the coefficient

     This function will export the RSA private key's parameters found in
     the given structure.  The new parameters will be allocated using
     'gnutls_malloc()' and will be stored in the appropriate datum.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_export_rsa_raw2
-----------------------------------

 -- Function: int gnutls_x509_privkey_export_rsa_raw2
          (gnutls_x509_privkey_t KEY, gnutls_datum_t * M, gnutls_datum_t
          * E, gnutls_datum_t * D, gnutls_datum_t * P, gnutls_datum_t *
          Q, gnutls_datum_t * U, gnutls_datum_t * E1, gnutls_datum_t *
          E2)
     KEY: a structure that holds the rsa parameters

     M: will hold the modulus

     E: will hold the public exponent

     D: will hold the private exponent

     P: will hold the first prime (p)

     Q: will hold the second prime (q)

     U: will hold the coefficient

     E1: will hold e1 = d mod (p-1)

     E2: will hold e2 = d mod (q-1)

     This function will export the RSA private key's parameters found in
     the given structure.  The new parameters will be allocated using
     'gnutls_malloc()' and will be stored in the appropriate datum.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 2.12.0

gnutls_x509_privkey_fix
-----------------------

 -- Function: int gnutls_x509_privkey_fix (gnutls_x509_privkey_t KEY)
     KEY: Holds the key

     This function will recalculate the secondary parameters in a key.
     In RSA keys, this can be the coefficient and exponent1,2.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_generate
----------------------------

 -- Function: int gnutls_x509_privkey_generate (gnutls_x509_privkey_t
          KEY, gnutls_pk_algorithm_t ALGO, unsigned int BITS, unsigned
          int FLAGS)
     KEY: should contain a 'gnutls_x509_privkey_t' structure

     ALGO: is one of the algorithms in 'gnutls_pk_algorithm_t' .

     BITS: the size of the modulus

     FLAGS: unused for now.  Must be 0.

     This function will generate a random private key.  Note that this
     function must be called on an empty private key.

     Note that when generating an elliptic curve key, the curve can be
     substituted in the place of the bits parameter using the
     'GNUTLS_CURVE_TO_BITS()' macro.

     For DSA keys, if the subgroup size needs to be specified check the
     'GNUTLS_SUBGROUP_TO_BITS()' macro.

     Do not set the number of bits directly, use
     'gnutls_sec_param_to_pk_bits()' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_get_key_id
------------------------------

 -- Function: int gnutls_x509_privkey_get_key_id (gnutls_x509_privkey_t
          KEY, unsigned int FLAGS, unsigned char * OUTPUT_DATA, size_t *
          OUTPUT_DATA_SIZE)
     KEY: Holds the key

     FLAGS: should be 0 for now

     OUTPUT_DATA: will contain the key ID

     OUTPUT_DATA_SIZE: holds the size of output_data (and will be
     replaced by the actual size of parameters)

     This function will return a unique ID that depends on the public
     key parameters.  This ID can be used in checking whether a
     certificate corresponds to the given key.

     If the buffer provided is not long enough to hold the output, then
     * 'output_data_size' is updated and 'GNUTLS_E_SHORT_MEMORY_BUFFER'
     will be returned.  The output will normally be a SHA-1 hash output,
     which is 20 bytes.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_get_pk_algorithm
------------------------------------

 -- Function: int gnutls_x509_privkey_get_pk_algorithm
          (gnutls_x509_privkey_t KEY)
     KEY: should contain a 'gnutls_x509_privkey_t' structure

     This function will return the public key algorithm of a private
     key.

     *Returns:* a member of the 'gnutls_pk_algorithm_t' enumeration on
     success, or a negative error code on error.

gnutls_x509_privkey_get_pk_algorithm2
-------------------------------------

 -- Function: int gnutls_x509_privkey_get_pk_algorithm2
          (gnutls_x509_privkey_t KEY, unsigned int * BITS)
     KEY: should contain a 'gnutls_x509_privkey_t' structure

     BITS: The number of bits in the public key algorithm

     This function will return the public key algorithm of a private
     key.

     *Returns:* a member of the 'gnutls_pk_algorithm_t' enumeration on
     success, or a negative error code on error.

gnutls_x509_privkey_import
--------------------------

 -- Function: int gnutls_x509_privkey_import (gnutls_x509_privkey_t KEY,
          const gnutls_datum_t * DATA, gnutls_x509_crt_fmt_t FORMAT)
     KEY: The structure to store the parsed key

     DATA: The DER or PEM encoded certificate.

     FORMAT: One of DER or PEM

     This function will convert the given DER or PEM encoded key to the
     native 'gnutls_x509_privkey_t' format.  The output will be stored
     in 'key' .

     If the key is PEM encoded it should have a header that contains
     "PRIVATE KEY". Note that this function falls back to PKCS '8'
     decoding without password, if the default format fails to import.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_import2
---------------------------

 -- Function: int gnutls_x509_privkey_import2 (gnutls_x509_privkey_t
          KEY, const gnutls_datum_t * DATA, gnutls_x509_crt_fmt_t
          FORMAT, const char * PASSWORD, unsigned int FLAGS)
     KEY: The structure to store the parsed key

     DATA: The DER or PEM encoded key.

     FORMAT: One of DER or PEM

     PASSWORD: A password (optional)

     FLAGS: an ORed sequence of gnutls_pkcs_encrypt_flags_t

     This function will import the given DER or PEM encoded key, to the
     native 'gnutls_x509_privkey_t' format, irrespective of the input
     format.  The input format is auto-detected.

     The supported formats are basic unencrypted key, PKCS8, PKCS12, and
     the openssl format.

     If the provided key is encrypted but no password was given, then
     'GNUTLS_E_DECRYPTION_FAILED' is returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_import_dsa_raw
----------------------------------

 -- Function: int gnutls_x509_privkey_import_dsa_raw
          (gnutls_x509_privkey_t KEY, const gnutls_datum_t * P, const
          gnutls_datum_t * Q, const gnutls_datum_t * G, const
          gnutls_datum_t * Y, const gnutls_datum_t * X)
     KEY: The structure to store the parsed key

     P: holds the p

     Q: holds the q

     G: holds the g

     Y: holds the y

     X: holds the x

     This function will convert the given DSA raw parameters to the
     native 'gnutls_x509_privkey_t' format.  The output will be stored
     in 'key' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_import_ecc_raw
----------------------------------

 -- Function: int gnutls_x509_privkey_import_ecc_raw
          (gnutls_x509_privkey_t KEY, gnutls_ecc_curve_t CURVE, const
          gnutls_datum_t * X, const gnutls_datum_t * Y, const
          gnutls_datum_t * K)
     KEY: The structure to store the parsed key

     CURVE: holds the curve

     X: holds the x

     Y: holds the y

     K: holds the k

     This function will convert the given elliptic curve parameters to
     the native 'gnutls_x509_privkey_t' format.  The output will be
     stored in 'key' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0

gnutls_x509_privkey_import_openssl
----------------------------------

 -- Function: int gnutls_x509_privkey_import_openssl
          (gnutls_x509_privkey_t KEY, const gnutls_datum_t * DATA, const
          char * PASSWORD)
     KEY: The structure to store the parsed key

     DATA: The DER or PEM encoded key.

     PASSWORD: the password to decrypt the key (if it is encrypted).

     This function will convert the given PEM encrypted to the native
     gnutls_x509_privkey_t format.  The output will be stored in 'key' .

     The 'password' should be in ASCII. If the password is not provided
     or wrong then 'GNUTLS_E_DECRYPTION_FAILED' will be returned.

     If the Certificate is PEM encoded it should have a header of
     "PRIVATE KEY" and the "DEK-Info" header.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_import_pkcs8
--------------------------------

 -- Function: int gnutls_x509_privkey_import_pkcs8
          (gnutls_x509_privkey_t KEY, const gnutls_datum_t * DATA,
          gnutls_x509_crt_fmt_t FORMAT, const char * PASSWORD, unsigned
          int FLAGS)
     KEY: The structure to store the parsed key

     DATA: The DER or PEM encoded key.

     FORMAT: One of DER or PEM

     PASSWORD: the password to decrypt the key (if it is encrypted).

     FLAGS: 0 if encrypted or GNUTLS_PKCS_PLAIN if not encrypted.

     This function will convert the given DER or PEM encoded PKCS8 2.0
     encrypted key to the native gnutls_x509_privkey_t format.  The
     output will be stored in 'key' .  Both RSA and DSA keys can be
     imported, and flags can only be used to indicate an unencrypted
     key.

     The 'password' can be either ASCII or UTF-8 in the default PBES2
     encryption schemas, or ASCII for the PKCS12 schemas.

     If the Certificate is PEM encoded it should have a header of
     "ENCRYPTED PRIVATE KEY", or "PRIVATE KEY". You only need to specify
     the flags if the key is DER encoded, since in that case the
     encryption status cannot be auto-detected.

     If the 'GNUTLS_PKCS_PLAIN' flag is specified and the supplied data
     are encrypted then 'GNUTLS_E_DECRYPTION_FAILED' is returned.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_import_rsa_raw
----------------------------------

 -- Function: int gnutls_x509_privkey_import_rsa_raw
          (gnutls_x509_privkey_t KEY, const gnutls_datum_t * M, const
          gnutls_datum_t * E, const gnutls_datum_t * D, const
          gnutls_datum_t * P, const gnutls_datum_t * Q, const
          gnutls_datum_t * U)
     KEY: The structure to store the parsed key

     M: holds the modulus

     E: holds the public exponent

     D: holds the private exponent

     P: holds the first prime (p)

     Q: holds the second prime (q)

     U: holds the coefficient

     This function will convert the given RSA raw parameters to the
     native 'gnutls_x509_privkey_t' format.  The output will be stored
     in 'key' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_import_rsa_raw2
-----------------------------------

 -- Function: int gnutls_x509_privkey_import_rsa_raw2
          (gnutls_x509_privkey_t KEY, const gnutls_datum_t * M, const
          gnutls_datum_t * E, const gnutls_datum_t * D, const
          gnutls_datum_t * P, const gnutls_datum_t * Q, const
          gnutls_datum_t * U, const gnutls_datum_t * E1, const
          gnutls_datum_t * E2)
     KEY: The structure to store the parsed key

     M: holds the modulus

     E: holds the public exponent

     D: holds the private exponent

     P: holds the first prime (p)

     Q: holds the second prime (q)

     U: holds the coefficient (optional)

     E1: holds e1 = d mod (p-1) (optional)

     E2: holds e2 = d mod (q-1) (optional)

     This function will convert the given RSA raw parameters to the
     native 'gnutls_x509_privkey_t' format.  The output will be stored
     in 'key' .

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_init
------------------------

 -- Function: int gnutls_x509_privkey_init (gnutls_x509_privkey_t * KEY)
     KEY: The structure to be initialized

     This function will initialize an private key structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_privkey_sec_param
-----------------------------

 -- Function: gnutls_sec_param_t gnutls_x509_privkey_sec_param
          (gnutls_x509_privkey_t KEY)
     KEY: a key structure

     This function will return the security parameter appropriate with
     this private key.

     *Returns:* On success, a valid security parameter is returned
     otherwise 'GNUTLS_SEC_PARAM_UNKNOWN' is returned.

     *Since:* 2.12.0

gnutls_x509_privkey_verify_params
---------------------------------

 -- Function: int gnutls_x509_privkey_verify_params
          (gnutls_x509_privkey_t KEY)
     KEY: should contain a 'gnutls_x509_privkey_t' structure

     This function will verify the private key parameters.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

gnutls_x509_rdn_get
-------------------

 -- Function: int gnutls_x509_rdn_get (const gnutls_datum_t * IDN, char
          * BUF, size_t * BUF_SIZE)
     IDN: should contain a DER encoded RDN sequence

     BUF: a pointer to a structure to hold the peer's name

     BUF_SIZE: holds the size of 'buf'

     This function will return the name of the given RDN sequence.  The
     name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in
     RFC4514.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or
     'GNUTLS_E_SHORT_MEMORY_BUFFER' is returned and * 'buf_size' is
     updated if the provided buffer is not long enough, otherwise a
     negative error value.

gnutls_x509_rdn_get_by_oid
--------------------------

 -- Function: int gnutls_x509_rdn_get_by_oid (const gnutls_datum_t *
          IDN, const char * OID, int INDX, unsigned int RAW_FLAG, void *
          BUF, size_t * BUF_SIZE)
     IDN: should contain a DER encoded RDN sequence

     OID: an Object Identifier

     INDX: In case multiple same OIDs exist in the RDN indicates which
     to send.  Use 0 for the first one.

     RAW_FLAG: If non-zero then the raw DER data are returned.

     BUF: a pointer to a structure to hold the peer's name

     BUF_SIZE: holds the size of 'buf'

     This function will return the name of the given Object identifier,
     of the RDN sequence.  The name will be encoded using the rules from
     RFC4514.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or
     'GNUTLS_E_SHORT_MEMORY_BUFFER' is returned and * 'buf_size' is
     updated if the provided buffer is not long enough, otherwise a
     negative error value.

gnutls_x509_rdn_get_oid
-----------------------

 -- Function: int gnutls_x509_rdn_get_oid (const gnutls_datum_t * IDN,
          int INDX, void * BUF, size_t * BUF_SIZE)
     IDN: should contain a DER encoded RDN sequence

     INDX: Indicates which OID to return.  Use 0 for the first one.

     BUF: a pointer to a structure to hold the peer's name OID

     BUF_SIZE: holds the size of 'buf'

     This function will return the specified Object identifier, of the
     RDN sequence.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned, or
     'GNUTLS_E_SHORT_MEMORY_BUFFER' is returned and * 'buf_size' is
     updated if the provided buffer is not long enough, otherwise a
     negative error value.

     *Since:* 2.4.0

gnutls_x509_trust_list_add_cas
------------------------------

 -- Function: int gnutls_x509_trust_list_add_cas
          (gnutls_x509_trust_list_t LIST, const gnutls_x509_crt_t *
          CLIST, unsigned CLIST_SIZE, unsigned int FLAGS)
     LIST: The structure of the list

     CLIST: A list of CAs

     CLIST_SIZE: The length of the CA list

     FLAGS: should be 0 or an or'ed sequence of 'GNUTLS_TL' options.

     This function will add the given certificate authorities to the
     trusted list.  The list of CAs must not be deinitialized during
     this structure's lifetime.

     If the flag 'GNUTLS_TL_NO_DUPLICATES' is specified, then the
     provided 'clist' entries that are duplicates will not be added to
     the list and will be deinitialized.

     *Returns:* The number of added elements is returned.

     *Since:* 3.0.0

gnutls_x509_trust_list_add_crls
-------------------------------

 -- Function: int gnutls_x509_trust_list_add_crls
          (gnutls_x509_trust_list_t LIST, const gnutls_x509_crl_t *
          CRL_LIST, int CRL_SIZE, unsigned int FLAGS, unsigned int
          VERIFICATION_FLAGS)
     LIST: The structure of the list

     CRL_LIST: A list of CRLs

     CRL_SIZE: The length of the CRL list

     FLAGS: if GNUTLS_TL_VERIFY_CRL is given the CRLs will be verified
     before being added.

     VERIFICATION_FLAGS: gnutls_certificate_verify_flags if flags
     specifies GNUTLS_TL_VERIFY_CRL

     This function will add the given certificate revocation lists to
     the trusted list.  The list of CRLs must not be deinitialized
     during this structure's lifetime.

     This function must be called after
     'gnutls_x509_trust_list_add_cas()' to allow verifying the CRLs for
     validity.  If the flag 'GNUTLS_TL_NO_DUPLICATES' is given, then any
     provided CRLs that are a duplicate, will be deinitialized and not
     added to the list (that assumes that
     'gnutls_x509_trust_list_deinit()' will be called with all=1).

     *Returns:* The number of added elements is returned.

     *Since:* 3.0

gnutls_x509_trust_list_add_named_crt
------------------------------------

 -- Function: int gnutls_x509_trust_list_add_named_crt
          (gnutls_x509_trust_list_t LIST, gnutls_x509_crt_t CERT, const
          void * NAME, size_t NAME_SIZE, unsigned int FLAGS)
     LIST: The structure of the list

     CERT: A certificate

     NAME: An identifier for the certificate

     NAME_SIZE: The size of the identifier

     FLAGS: should be 0.

     This function will add the given certificate to the trusted list
     and associate it with a name.  The certificate will not be be used
     for verification with 'gnutls_x509_trust_list_verify_crt()' but
     only with 'gnutls_x509_trust_list_verify_named_crt()' .

     In principle this function can be used to set individual "server"
     certificates that are trusted by the user for that specific server
     but for no other purposes.

     The certificate must not be deinitialized during the lifetime of
     the trusted list.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0.0

gnutls_x509_trust_list_add_system_trust
---------------------------------------

 -- Function: int gnutls_x509_trust_list_add_system_trust
          (gnutls_x509_trust_list_t LIST, unsigned int TL_FLAGS,
          unsigned int TL_VFLAGS)
     LIST: The structure of the list

     TL_FLAGS: GNUTLS_TL_*

     TL_VFLAGS: gnutls_certificate_verify_flags if flags specifies
     GNUTLS_TL_VERIFY_CRL

     This function adds the system's default trusted certificate
     authorities to the trusted list.  Note that on unsupported systems
     this function returns 'GNUTLS_E_UNIMPLEMENTED_FEATURE' .

     This function implies the flag 'GNUTLS_TL_NO_DUPLICATES' .

     *Returns:* The number of added elements or a negative error code on
     error.

     *Since:* 3.1

gnutls_x509_trust_list_add_trust_dir
------------------------------------

 -- Function: int gnutls_x509_trust_list_add_trust_dir
          (gnutls_x509_trust_list_t LIST, const char * CA_DIR, const
          char * CRL_DIR, gnutls_x509_crt_fmt_t TYPE, unsigned int
          TL_FLAGS, unsigned int TL_VFLAGS)
     LIST: The structure of the list

     CA_DIR: A directory containing the CAs (optional)

     CRL_DIR: A directory containing a list of CRLs (optional)

     TYPE: The format of the certificates

     TL_FLAGS: GNUTLS_TL_*

     TL_VFLAGS: gnutls_certificate_verify_flags if flags specifies
     GNUTLS_TL_VERIFY_CRL

     This function will add the given certificate authorities to the
     trusted list.  Only directories are accepted by this function.

     *Returns:* The number of added elements is returned.

     *Since:* 3.3.6

gnutls_x509_trust_list_add_trust_file
-------------------------------------

 -- Function: int gnutls_x509_trust_list_add_trust_file
          (gnutls_x509_trust_list_t LIST, const char * CA_FILE, const
          char * CRL_FILE, gnutls_x509_crt_fmt_t TYPE, unsigned int
          TL_FLAGS, unsigned int TL_VFLAGS)
     LIST: The structure of the list

     CA_FILE: A file containing a list of CAs (optional)

     CRL_FILE: A file containing a list of CRLs (optional)

     TYPE: The format of the certificates

     TL_FLAGS: GNUTLS_TL_*

     TL_VFLAGS: gnutls_certificate_verify_flags if flags specifies
     GNUTLS_TL_VERIFY_CRL

     This function will add the given certificate authorities to the
     trusted list.  PKCS '11' URLs are also accepted, instead of files,
     by this function.  A PKCS '11' URL implies a trust database (a
     specially marked module in p11-kit); the URL "pkcs11:" implies all
     trust databases in the system.  Only a single URL specifying trust
     databases can be set; they cannot be stacked with multiple calls.

     *Returns:* The number of added elements is returned.

     *Since:* 3.1

gnutls_x509_trust_list_add_trust_mem
------------------------------------

 -- Function: int gnutls_x509_trust_list_add_trust_mem
          (gnutls_x509_trust_list_t LIST, const gnutls_datum_t * CAS,
          const gnutls_datum_t * CRLS, gnutls_x509_crt_fmt_t TYPE,
          unsigned int TL_FLAGS, unsigned int TL_VFLAGS)
     LIST: The structure of the list

     CAS: A buffer containing a list of CAs (optional)

     CRLS: A buffer containing a list of CRLs (optional)

     TYPE: The format of the certificates

     TL_FLAGS: GNUTLS_TL_*

     TL_VFLAGS: gnutls_certificate_verify_flags if flags specifies
     GNUTLS_TL_VERIFY_CRL

     This function will add the given certificate authorities to the
     trusted list.

     *Returns:* The number of added elements is returned.

     *Since:* 3.1

gnutls_x509_trust_list_deinit
-----------------------------

 -- Function: void gnutls_x509_trust_list_deinit
          (gnutls_x509_trust_list_t LIST, unsigned int ALL)
     LIST: The structure to be deinitialized

     ALL: if non-zero it will deinitialize all the certificates and CRLs
     contained in the structure.

     This function will deinitialize a trust list.  Note that the 'all'
     flag should be typically non-zero unless you have specified your
     certificates using 'gnutls_x509_trust_list_add_cas()' and you want
     to prevent them from being deinitialized by this function.

     *Since:* 3.0.0

gnutls_x509_trust_list_get_issuer
---------------------------------

 -- Function: int gnutls_x509_trust_list_get_issuer
          (gnutls_x509_trust_list_t LIST, gnutls_x509_crt_t CERT,
          gnutls_x509_crt_t * ISSUER, unsigned int FLAGS)
     LIST: The structure of the list

     CERT: is the certificate to find issuer for

     ISSUER: Will hold the issuer if any.  Should be treated as
     constant.

     FLAGS: Use zero or 'GNUTLS_TL_GET_COPY'

     This function will find the issuer of the given certificate.  If
     the flag 'GNUTLS_TL_GET_COPY' is specified a copy of the issuer
     will be returned which must be freed using
     'gnutls_x509_crt_deinit()' .  Note that the flag
     'GNUTLS_TL_GET_COPY' is required for this function to work with
     PKCS '11' trust lists in a thread-safe way.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0

gnutls_x509_trust_list_init
---------------------------

 -- Function: int gnutls_x509_trust_list_init (gnutls_x509_trust_list_t
          * LIST, unsigned int SIZE)
     LIST: The structure to be initialized

     SIZE: The size of the internal hash table.  Use (0) for default
     size.

     This function will initialize an X.509 trust list structure.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0.0

gnutls_x509_trust_list_remove_cas
---------------------------------

 -- Function: int gnutls_x509_trust_list_remove_cas
          (gnutls_x509_trust_list_t LIST, const gnutls_x509_crt_t *
          CLIST, int CLIST_SIZE)
     LIST: The structure of the list

     CLIST: A list of CAs

     CLIST_SIZE: The length of the CA list

     This function will remove the given certificate authorities from
     the trusted list.

     Note that this function can accept certificates and authorities not
     yet known.  In that case they will be kept in a separate black list
     that will be used during certificate verification.  Unlike
     'gnutls_x509_trust_list_add_cas()' there is no deinitialization
     restriction for certificate list provided in this function.

     *Returns:* The number of removed elements is returned.

     *Since:* 3.1.10

gnutls_x509_trust_list_remove_trust_file
----------------------------------------

 -- Function: int gnutls_x509_trust_list_remove_trust_file
          (gnutls_x509_trust_list_t LIST, const char * CA_FILE,
          gnutls_x509_crt_fmt_t TYPE)
     LIST: The structure of the list

     CA_FILE: A file containing a list of CAs

     TYPE: The format of the certificates

     This function will remove the given certificate authorities from
     the trusted list, and add them into a black list when needed.  PKCS
     11 URLs are also accepted, instead of files, by this function.

     See also 'gnutls_x509_trust_list_remove_cas()' .

     *Returns:* The number of added elements is returned.

     *Since:* 3.1.10

gnutls_x509_trust_list_remove_trust_mem
---------------------------------------

 -- Function: int gnutls_x509_trust_list_remove_trust_mem
          (gnutls_x509_trust_list_t LIST, const gnutls_datum_t * CAS,
          gnutls_x509_crt_fmt_t TYPE)
     LIST: The structure of the list

     CAS: A buffer containing a list of CAs (optional)

     TYPE: The format of the certificates

     This function will remove the provided certificate authorities from
     the trusted list, and add them into a black list when needed.

     See also 'gnutls_x509_trust_list_remove_cas()' .

     *Returns:* The number of removed elements is returned.

     *Since:* 3.1.10

gnutls_x509_trust_list_verify_crt
---------------------------------

 -- Function: int gnutls_x509_trust_list_verify_crt
          (gnutls_x509_trust_list_t LIST, gnutls_x509_crt_t * CERT_LIST,
          unsigned int CERT_LIST_SIZE, unsigned int FLAGS, unsigned int
          * VOUTPUT, gnutls_verify_output_function FUNC)
     LIST: The structure of the list

     CERT_LIST: is the certificate list to be verified

     CERT_LIST_SIZE: is the certificate list size

     FLAGS: Flags that may be used to change the verification algorithm.
     Use OR of the gnutls_certificate_verify_flags enumerations.

     VOUTPUT: will hold the certificate verification output.

     FUNC: If non-null will be called on each chain element verification
     with the output.

     This function will try to verify the given certificate and return
     its status.  The 'verify' parameter will hold an OR'ed sequence of
     'gnutls_certificate_status_t' flags.

     Additionally a certificate verification profile can be specified
     from the ones in 'gnutls_certificate_verification_profiles_t' by
     ORing the result of 'GNUTLS_PROFILE_TO_VFLAGS()' to the
     verification flags.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0

gnutls_x509_trust_list_verify_crt2
----------------------------------

 -- Function: int gnutls_x509_trust_list_verify_crt2
          (gnutls_x509_trust_list_t LIST, gnutls_x509_crt_t * CERT_LIST,
          unsigned int CERT_LIST_SIZE, gnutls_typed_vdata_st * DATA,
          unsigned int ELEMENTS, unsigned int FLAGS, unsigned int *
          VOUTPUT, gnutls_verify_output_function FUNC)
     LIST: The structure of the list

     CERT_LIST: is the certificate list to be verified

     CERT_LIST_SIZE: is the certificate list size

     DATA: an array of typed data

     ELEMENTS: the number of data elements

     FLAGS: Flags that may be used to change the verification algorithm.
     Use OR of the gnutls_certificate_verify_flags enumerations.

     VOUTPUT: will hold the certificate verification output.

     FUNC: If non-null will be called on each chain element verification
     with the output.

     This function will try to verify the given certificate and return
     its status.  The 'verify' parameter will hold an OR'ed sequence of
     'gnutls_certificate_status_t' flags.

     Additionally a certificate verification profile can be specified
     from the ones in 'gnutls_certificate_verification_profiles_t' by
     ORing the result of 'GNUTLS_PROFILE_TO_VFLAGS()' to the
     verification flags.

     The acceptable 'data' types are 'GNUTLS_DT_DNS_HOSTNAME' and
     'GNUTLS_DT_KEY_PURPOSE_OID' .  The former accepts as data a
     null-terminated hostname, and the latter a null-terminated object
     identifier (e.g., 'GNUTLS_KP_TLS_WWW_SERVER' ).  If a DNS hostname
     is provided then this function will compare the hostname in the
     certificate against the given.  If names do not match the
     'GNUTLS_CERT_UNEXPECTED_OWNER' status flag will be set.  If a key
     purpose OID is provided and the end-certificate contains the
     extended key usage PKIX extension, it will be required to be have
     the provided key purpose or be marked for any purpose, otherwise
     verification will fail with
     'GNUTLS_CERT_SIGNER_CONSTRAINTS_FAILURE' status.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.  Note that verification failure
     will not result to an error code, only 'voutput' will be updated.

     *Since:* 3.3.8

gnutls_x509_trust_list_verify_named_crt
---------------------------------------

 -- Function: int gnutls_x509_trust_list_verify_named_crt
          (gnutls_x509_trust_list_t LIST, gnutls_x509_crt_t CERT, const
          void * NAME, size_t NAME_SIZE, unsigned int FLAGS, unsigned
          int * VOUTPUT, gnutls_verify_output_function FUNC)
     LIST: The structure of the list

     CERT: is the certificate to be verified

     NAME: is the certificate's name

     NAME_SIZE: is the certificate's name size

     FLAGS: Flags that may be used to change the verification algorithm.
     Use OR of the gnutls_certificate_verify_flags enumerations.

     VOUTPUT: will hold the certificate verification output.

     FUNC: If non-null will be called on each chain element verification
     with the output.

     This function will try to find a certificate that is associated
     with the provided name -see
     'gnutls_x509_trust_list_add_named_crt()' .  If a match is found the
     certificate is considered valid.  In addition to that this function
     will also check CRLs.  The 'voutput' parameter will hold an OR'ed
     sequence of 'gnutls_certificate_status_t' flags.

     Additionally a certificate verification profile can be specified
     from the ones in 'gnutls_certificate_verification_profiles_t' by
     ORing the result of 'GNUTLS_PROFILE_TO_VFLAGS()' to the
     verification flags.

     *Returns:* On success, 'GNUTLS_E_SUCCESS' (0) is returned,
     otherwise a negative error value.

     *Since:* 3.0.0

