From ed7ec0cdf577ffbb0b15145340cf51596ca3eb89 Mon Sep 17 00:00:00 2001

From: Jakub Jelen <jjelen@redhat.com>

Date: Tue, 14 May 2019 10:45:45 +0200

Subject: [PATCH] Use high-level OpenSSL API for signatures

---

 digest-openssl.c |  16 ++++

 digest.h         |   6 ++

 ssh-dss.c        |  65 ++++++++++------

 ssh-ecdsa.c      |  69 ++++++++++-------

 ssh-rsa.c        | 193 +++++++++--------------------------------------

 sshkey.c         |  77 +++++++++++++++++++

 sshkey.h         |   4 +

 7 files changed, 221 insertions(+), 209 deletions(-)

diff --git a/digest-openssl.c b/digest-openssl.c

index da7ed72bc..6a21d8adb 100644

--- a/digest-openssl.c

+++ b/digest-openssl.c

@@ -63,6 +63,22 @@ const struct ssh_digest digests[] = {

 	{ -1,			NULL,		0,	NULL },

 };

+const EVP_MD *

+ssh_digest_to_md(int digest_type)

+{

+	switch (digest_type) {

+	case SSH_DIGEST_SHA1:

+		return EVP_sha1();

+	case SSH_DIGEST_SHA256:

+		return EVP_sha256();

+	case SSH_DIGEST_SHA384:

+		return EVP_sha384();

+	case SSH_DIGEST_SHA512:

+		return EVP_sha512();

+	}

+	return NULL;

+}

+

 static const struct ssh_digest *

 ssh_digest_by_alg(int alg)

 {

diff --git a/digest.h b/digest.h

index 274574d0e..c7ceeb36f 100644

--- a/digest.h

+++ b/digest.h

@@ -32,6 +32,12 @@

 struct sshbuf;

 struct ssh_digest_ctx;

+#ifdef WITH_OPENSSL

+#include <openssl/evp.h>

+/* Converts internal digest representation to the OpenSSL one */

+const EVP_MD *ssh_digest_to_md(int digest_type);

+#endif

+

 /* Looks up a digest algorithm by name */

 int ssh_digest_alg_by_name(const char *name);

diff --git a/ssh-dss.c b/ssh-dss.c

index a23c383dc..ea45e7275 100644

--- a/ssh-dss.c

+++ b/ssh-dss.c

@@ -52,11 +52,15 @@ int

     const u_char *data, size_t datalen,

     const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)

 {

+	EVP_PKEY *pkey = NULL;

 	DSA_SIG *sig = NULL;

 	const BIGNUM *sig_r, *sig_s;

-	u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];

-	size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);

+	u_char sigblob[SIGBLOB_LEN];

+	size_t rlen, slen;

+	int len;

 	struct sshbuf *b = NULL;

+	u_char *sigb = NULL;

+	const u_char *psig = NULL;

 	int ret = SSH_ERR_INVALID_ARGUMENT;

 	if (lenp != NULL)

@@ -67,17 +71,24 @@ ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,

 	if (key == NULL || key->dsa == NULL ||

 	    sshkey_type_plain(key->type) != KEY_DSA)

 		return SSH_ERR_INVALID_ARGUMENT;

-	if (dlen == 0)

-		return SSH_ERR_INTERNAL_ERROR;

-	if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,

-	    digest, sizeof(digest))) != 0)

+	if ((pkey = EVP_PKEY_new()) == NULL ||

+	    EVP_PKEY_set1_DSA(pkey, key->dsa) != 1)

+		return SSH_ERR_ALLOC_FAIL;

+	ret = sshkey_calculate_signature(pkey, SSH_DIGEST_SHA1, &sigb, &len,

+	    data, datalen);

+	EVP_PKEY_free(pkey);

+	if (ret < 0) {

 		goto out;

+	}

-	if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {

+	psig = sigb;

+	if ((sig = d2i_DSA_SIG(NULL, &psig, len)) == NULL) {

 		ret = SSH_ERR_LIBCRYPTO_ERROR;

 		goto out;

 	}

+	free(sigb);

+	sigb = NULL;

 	DSA_SIG_get0(sig, &sig_r, &sig_s);

 	rlen = BN_num_bytes(sig_r);

@@ -110,7 +121,7 @@ ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,

 		*lenp = len;

 	ret = 0;

  out:

-	explicit_bzero(digest, sizeof(digest));

+	free(sigb);

 	DSA_SIG_free(sig);

 	sshbuf_free(b);

 	return ret;

@@ -121,20 +132,20 @@ ssh_dss_verify(const struct sshkey *key,

     const u_char *data, size_t dlen, const char *alg, u_int compat,

     struct sshkey_sig_details **detailsp)

 {

+	EVP_PKEY *pkey = NULL;

 	DSA_SIG *dsig = NULL;

 	BIGNUM *sig_r = NULL, *sig_s = NULL;

-	u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;

-	size_t len, hlen = ssh_digest_bytes(SSH_DIGEST_SHA1);

+	u_char *sigblob = NULL;

+	size_t len, slen;

 	int ret = SSH_ERR_INTERNAL_ERROR;

 	struct sshbuf *b = NULL;

 	char *ktype = NULL;

+	u_char *sigb = NULL, *psig = NULL;

 	if (key == NULL || key->dsa == NULL ||

 	    sshkey_type_plain(key->type) != KEY_DSA ||

 	    sig == NULL || siglen == 0)

 		return SSH_ERR_INVALID_ARGUMENT;

-	if (hlen == 0)

-		return SSH_ERR_INTERNAL_ERROR;

 	/* fetch signature */

 	if ((b = sshbuf_from(sig, siglen)) == NULL)

@@ -176,25 +187,31 @@ ssh_dss_verify(const struct sshkey *key,

 	}

 	sig_r = sig_s = NULL; /* transferred */

-	/* sha1 the data */

-	if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, dlen,

-	    digest, sizeof(digest))) != 0)

+	if ((slen = i2d_DSA_SIG(sig, NULL)) == 0) {

+		ret = SSH_ERR_LIBCRYPTO_ERROR;

 		goto out;

-

-	switch (DSA_do_verify(digest, hlen, dsig, key->dsa)) {

-	case 1:

-		ret = 0;

-		break;

-	case 0:

-		ret = SSH_ERR_SIGNATURE_INVALID;

+	}

+	if ((sigb = malloc(slen)) == NULL) {

+		ret = SSH_ERR_ALLOC_FAIL;

 		goto out;

-	default:

+	}

+	psig = sigb;

+	if ((slen = i2d_DSA_SIG(sig, &psig)) == 0) {

 		ret = SSH_ERR_LIBCRYPTO_ERROR;

 		goto out;

 	}

+	if ((pkey = EVP_PKEY_new()) == NULL ||

+	    EVP_PKEY_set1_DSA(pkey, key->dsa) != 1) {

+		ret = SSH_ERR_ALLOC_FAIL;

+		goto out;

+	}

+	ret = sshkey_verify_signature(pkey, SSH_DIGEST_SHA1, data, dlen,

+	    sigb, slen);

+	EVP_PKEY_free(pkey);

+

  out:

-	explicit_bzero(digest, sizeof(digest));

+	free(sigb);

 	DSA_SIG_free(dsig);

 	BN_clear_free(sig_r);

 	BN_clear_free(sig_s);

diff --git a/ssh-ecdsa.c b/ssh-ecdsa.c

index 599c7199d..b036796e8 100644

--- a/ssh-ecdsa.c

+++ b/ssh-ecdsa.c

@@ -50,11 +50,13 @@ int

     const u_char *data, size_t dlen,

     const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)

 {

+	EVP_PKEY *pkey = NULL;

 	ECDSA_SIG *esig = NULL;

+	unsigned char *sigb = NULL;

+	const unsigned char *psig;

 	const BIGNUM *sig_r, *sig_s;

 	int hash_alg;

-	u_char digest[SSH_DIGEST_MAX_LENGTH];

-	size_t len, hlen;

+	int len;

 	struct sshbuf *b = NULL, *bb = NULL;

 	int ret = SSH_ERR_INTERNAL_ERROR;

@@ -67,18 +69,24 @@ ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,

 	    sshkey_type_plain(key->type) != KEY_ECDSA)

 		return SSH_ERR_INVALID_ARGUMENT;

-	if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||

-	    (hlen = ssh_digest_bytes(hash_alg)) == 0)

+	if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1)

 		return SSH_ERR_INTERNAL_ERROR;

-	if ((ret = ssh_digest_memory(hash_alg, data, dlen,

-	    digest, sizeof(digest))) != 0)

+

+	if ((pkey = EVP_PKEY_new()) == NULL ||

+	    EVP_PKEY_set1_EC_KEY(pkey, key->ecdsa) != 1)

+		return SSH_ERR_ALLOC_FAIL;

+	ret = sshkey_calculate_signature(pkey, hash_alg, &sigb, &len, data,

+	    dlen);

+	EVP_PKEY_free(pkey);

+	if (ret < 0) {

 		goto out;

+	}

-	if ((esig = ECDSA_do_sign(digest, hlen, key->ecdsa)) == NULL) {

+	psig = sigb;

+	if (d2i_ECDSA_SIG(&esig, &psig, len) == NULL) {

 		ret = SSH_ERR_LIBCRYPTO_ERROR;

 		goto out;

 	}

-

 	if ((bb = sshbuf_new()) == NULL || (b = sshbuf_new()) == NULL) {

 		ret = SSH_ERR_ALLOC_FAIL;

 		goto out;

@@ -102,7 +110,7 @@ ssh_ecdsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,

 		*lenp = len;

 	ret = 0;

  out:

-	explicit_bzero(digest, sizeof(digest));

+	free(sigb);

 	sshbuf_free(b);

 	sshbuf_free(bb);

 	ECDSA_SIG_free(esig);

@@ -115,22 +123,21 @@ ssh_ecdsa_verify(const struct sshkey *key,

     const u_char *data, size_t dlen, const char *alg, u_int compat,

     struct sshkey_sig_details **detailsp)

 {

+	EVP_PKEY *pkey = NULL;

 	ECDSA_SIG *esig = NULL;

 	BIGNUM *sig_r = NULL, *sig_s = NULL;

-	int hash_alg;

-	u_char digest[SSH_DIGEST_MAX_LENGTH];

-	size_t hlen;

+	int hash_alg, len;

 	int ret = SSH_ERR_INTERNAL_ERROR;

 	struct sshbuf *b = NULL, *sigbuf = NULL;

 	char *ktype = NULL;

+	unsigned char *sigb = NULL, *psig = NULL;

 	if (key == NULL || key->ecdsa == NULL ||

 	    sshkey_type_plain(key->type) != KEY_ECDSA ||

 	    sig == NULL || siglen == 0)

 		return SSH_ERR_INVALID_ARGUMENT;

-	if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1 ||

-	    (hlen = ssh_digest_bytes(hash_alg)) == 0)

+	if ((hash_alg = sshkey_ec_nid_to_hash_alg(key->ecdsa_nid)) == -1)

 		return SSH_ERR_INTERNAL_ERROR;

 	/* fetch signature */

@@ -166,28 +173,36 @@ ssh_ecdsa_verify(const struct sshkey *key,

 	}

 	sig_r = sig_s = NULL; /* transferred */

-	if (sshbuf_len(sigbuf) != 0) {

-		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;

+	/* Figure out the length */

+	if ((len = i2d_ECDSA_SIG(esig, NULL)) == 0) {

+		ret = SSH_ERR_LIBCRYPTO_ERROR;

+		goto out;

+	}

+	if ((sigb = malloc(len)) == NULL) {

+		ret = SSH_ERR_ALLOC_FAIL;

 		goto out;

 	}

-	if ((ret = ssh_digest_memory(hash_alg, data, dlen,

-	    digest, sizeof(digest))) != 0)

+	psig = sigb;

+	if ((len = i2d_ECDSA_SIG(esig, &psig)) == 0) {

+		ret = SSH_ERR_LIBCRYPTO_ERROR;

 		goto out;

+	}

-	switch (ECDSA_do_verify(digest, hlen, esig, key->ecdsa)) {

-	case 1:

-		ret = 0;

-		break;

-	case 0:

-		ret = SSH_ERR_SIGNATURE_INVALID;

+	if (sshbuf_len(sigbuf) != 0) {

+		ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;

 		goto out;

-	default:

-		ret = SSH_ERR_LIBCRYPTO_ERROR;

+	}

+

+	if ((pkey = EVP_PKEY_new()) == NULL ||

+	    EVP_PKEY_set1_EC_KEY(pkey, key->ecdsa) != 1) {

+		ret =  SSH_ERR_ALLOC_FAIL;

 		goto out;

 	}

+	ret = sshkey_verify_signature(pkey, hash_alg, data, dlen, sigb, len);

+	EVP_PKEY_free(pkey);

  out:

-	explicit_bzero(digest, sizeof(digest));

+	free(sigb);

 	sshbuf_free(sigbuf);

 	sshbuf_free(b);

 	ECDSA_SIG_free(esig);

diff --git a/ssh-rsa.c b/ssh-rsa.c

index 9b14f9a9a..8ef3a6aca 100644

--- a/ssh-rsa.c

+++ b/ssh-rsa.c

@@ -37,7 +37,7 @@

 #include "openbsd-compat/openssl-compat.h"

-static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *);

+static int openssh_RSA_verify(int, const u_char *, size_t, u_char *, size_t, EVP_PKEY *);

 static u_int

 ssh_rsa_size(const struct sshkey *key)

@@ -90,21 +90,6 @@ rsa_hash_id_from_keyname(const char *alg)

 	return -1;

 }

-static int

-rsa_hash_alg_nid(int type)

-{

-	switch (type) {

-	case SSH_DIGEST_SHA1:

-		return NID_sha1;

-	case SSH_DIGEST_SHA256:

-		return NID_sha256;

-	case SSH_DIGEST_SHA512:

-		return NID_sha512;

-	default:

-		return -1;

-	}

-}

-

 int

 ssh_rsa_complete_crt_parameters(struct sshkey *key, const BIGNUM *iqmp)

 {

@@ -164,11 +149,10 @@ int

     const u_char *data, size_t datalen,

     const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)

 {

-	const BIGNUM *rsa_n;

-	u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL;

-	size_t slen = 0;

-	u_int hlen, len;

-	int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR;

+	EVP_PKEY *pkey = NULL;

+	u_char *sig = NULL;

+	int len, slen = 0;

+	int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;

 	struct sshbuf *b = NULL;

 	if (lenp != NULL)

@@ -180,33 +164,24 @@ ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,

 		hash_alg = SSH_DIGEST_SHA1;

 	else

 		hash_alg = rsa_hash_id_from_keyname(alg);

+

 	if (key == NULL || key->rsa == NULL || hash_alg == -1 ||

 	    sshkey_type_plain(key->type) != KEY_RSA)

 		return SSH_ERR_INVALID_ARGUMENT;

-	RSA_get0_key(key->rsa, &rsa_n, NULL, NULL);

-	if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE)

-		return SSH_ERR_KEY_LENGTH;

 	slen = RSA_size(key->rsa);

-	if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)

-		return SSH_ERR_INVALID_ARGUMENT;

-

-	/* hash the data */

-	nid = rsa_hash_alg_nid(hash_alg);

-	if ((hlen = ssh_digest_bytes(hash_alg)) == 0)

-		return SSH_ERR_INTERNAL_ERROR;

-	if ((ret = ssh_digest_memory(hash_alg, data, datalen,

-	    digest, sizeof(digest))) != 0)

-		goto out;

+	if (RSA_bits(key->rsa) < SSH_RSA_MINIMUM_MODULUS_SIZE)

+		return SSH_ERR_KEY_LENGTH;

-	if ((sig = malloc(slen)) == NULL) {

-		ret = SSH_ERR_ALLOC_FAIL;

+	if ((pkey = EVP_PKEY_new()) == NULL ||

+	    EVP_PKEY_set1_RSA(pkey, key->rsa) != 1)

+		return SSH_ERR_ALLOC_FAIL;

+	ret = sshkey_calculate_signature(pkey, hash_alg, &sig, &len, data,

+	    datalen);

+	EVP_PKEY_free(pkey);

+	if (ret < 0) {

 		goto out;

 	}

-	if (RSA_sign(nid, digest, hlen, sig, &len, key->rsa) != 1) {

-		ret = SSH_ERR_LIBCRYPTO_ERROR;

-		goto out;

-	}

 	if (len < slen) {

 		size_t diff = slen - len;

 		memmove(sig + diff, sig, len);

@@ -215,6 +190,7 @@ ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,

 		ret = SSH_ERR_INTERNAL_ERROR;

 		goto out;

 	}

+

 	/* encode signature */

 	if ((b = sshbuf_new()) == NULL) {

 		ret = SSH_ERR_ALLOC_FAIL;

@@ -235,7 +211,6 @@ ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,

 		*lenp = len;

 	ret = 0;

  out:

-	explicit_bzero(digest, sizeof(digest));

 	freezero(sig, slen);

 	sshbuf_free(b);

 	return ret;

@@ -246,10 +221,10 @@ ssh_rsa_verify(const struct sshkey *key,

     const u_char *data, size_t dlen, const char *alg, u_int compat,

     struct sshkey_sig_details **detailsp)

 {

-	const BIGNUM *rsa_n;

+	EVP_PKEY *pkey = NULL;

 	char *sigtype = NULL;

 	int hash_alg, want_alg, ret = SSH_ERR_INTERNAL_ERROR;

-	size_t len = 0, diff, modlen, hlen;

+	size_t len = 0, diff, modlen;

 	struct sshbuf *b = NULL;

 	u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL;

@@ -257,8 +232,7 @@ ssh_rsa_verify(const struct sshkey *key,

 	    sshkey_type_plain(key->type) != KEY_RSA ||

 	    sig == NULL || siglen == 0)

 		return SSH_ERR_INVALID_ARGUMENT;

-	RSA_get0_key(key->rsa, &rsa_n, NULL, NULL);

-	if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE)

+	if (RSA_bits(key->rsa) < SSH_RSA_MINIMUM_MODULUS_SIZE)

 		return SSH_ERR_KEY_LENGTH;

 	if ((b = sshbuf_from(sig, siglen)) == NULL)

@@ -310,16 +284,15 @@ ssh_rsa_verify(const struct sshkey *key,

 		explicit_bzero(sigblob, diff);

 		len = modlen;

 	}

-	if ((hlen = ssh_digest_bytes(hash_alg)) == 0) {

-		ret = SSH_ERR_INTERNAL_ERROR;

+

+	if ((pkey = EVP_PKEY_new()) == NULL ||

+	    EVP_PKEY_set1_RSA(pkey, key->rsa) != 1) {

+		ret = SSH_ERR_ALLOC_FAIL;

 		goto out;

 	}

-	if ((ret = ssh_digest_memory(hash_alg, data, dlen,

-	    digest, sizeof(digest))) != 0)

-		goto out;

+	ret = openssh_RSA_verify(hash_alg, data, dlen, sigblob, len, pkey);

+	EVP_PKEY_free(pkey);

-	ret = openssh_RSA_verify(hash_alg, digest, hlen, sigblob, len,

-	    key->rsa);

  out:

 	freezero(sigblob, len);

 	free(sigtype);

@@ -328,122 +301,26 @@ ssh_rsa_verify(const struct sshkey *key,

 	return ret;

 }

-/*

- * See:

- * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/

- * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn

- */

-

-/*

- * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)

- *	oiw(14) secsig(3) algorithms(2) 26 }

- */

-static const u_char id_sha1[] = {

-	0x30, 0x21, /* type Sequence, length 0x21 (33) */

-	0x30, 0x09, /* type Sequence, length 0x09 */

-	0x06, 0x05, /* type OID, length 0x05 */

-	0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */

-	0x05, 0x00, /* NULL */

-	0x04, 0x14  /* Octet string, length 0x14 (20), followed by sha1 hash */

-};

-

-/*

- * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html

- * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)

- *      organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)

- *      id-sha256(1) }

- */

-static const u_char id_sha256[] = {

-	0x30, 0x31, /* type Sequence, length 0x31 (49) */

-	0x30, 0x0d, /* type Sequence, length 0x0d (13) */

-	0x06, 0x09, /* type OID, length 0x09 */

-	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */

-	0x05, 0x00, /* NULL */

-	0x04, 0x20  /* Octet string, length 0x20 (32), followed by sha256 hash */

-};

-

-/*

- * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html

- * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)

- *      organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)

- *      id-sha256(3) }

- */

-static const u_char id_sha512[] = {

-	0x30, 0x51, /* type Sequence, length 0x51 (81) */

-	0x30, 0x0d, /* type Sequence, length 0x0d (13) */

-	0x06, 0x09, /* type OID, length 0x09 */

-	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */

-	0x05, 0x00, /* NULL */

-	0x04, 0x40  /* Octet string, length 0x40 (64), followed by sha512 hash */

-};

-

 static int

-rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp)

+openssh_RSA_verify(int hash_alg, const u_char *data, size_t datalen,

+    u_char *sigbuf, size_t siglen, EVP_PKEY *pkey)

 {

-	switch (hash_alg) {

-	case SSH_DIGEST_SHA1:

-		*oidp = id_sha1;

-		*oidlenp = sizeof(id_sha1);

-		break;

-	case SSH_DIGEST_SHA256:

-		*oidp = id_sha256;

-		*oidlenp = sizeof(id_sha256);

-		break;

-	case SSH_DIGEST_SHA512:

-		*oidp = id_sha512;

-		*oidlenp = sizeof(id_sha512);

-		break;

-	default:

-		return SSH_ERR_INVALID_ARGUMENT;

-	}

-	return 0;

-}

+	size_t rsasize = 0;

+	const RSA *rsa;

+	int ret;

-static int

-openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,

-    u_char *sigbuf, size_t siglen, RSA *rsa)

-{

-	size_t rsasize = 0, oidlen = 0, hlen = 0;

-	int ret, len, oidmatch, hashmatch;

-	const u_char *oid = NULL;

-	u_char *decrypted = NULL;

-

-	if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0)

-		return ret;

-	ret = SSH_ERR_INTERNAL_ERROR;

-	hlen = ssh_digest_bytes(hash_alg);

-	if (hashlen != hlen) {

-		ret = SSH_ERR_INVALID_ARGUMENT;

-		goto done;

-	}

+	rsa = EVP_PKEY_get0_RSA(pkey);

 	rsasize = RSA_size(rsa);

 	if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM ||

 	    siglen == 0 || siglen > rsasize) {

 		ret = SSH_ERR_INVALID_ARGUMENT;

 		goto done;

 	}

-	if ((decrypted = malloc(rsasize)) == NULL) {

-		ret = SSH_ERR_ALLOC_FAIL;

-		goto done;

-	}

-	if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,

-	    RSA_PKCS1_PADDING)) < 0) {

-		ret = SSH_ERR_LIBCRYPTO_ERROR;

-		goto done;

-	}

-	if (len < 0 || (size_t)len != hlen + oidlen) {

-		ret = SSH_ERR_INVALID_FORMAT;

-		goto done;

-	}

-	oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;

-	hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;

-	if (!oidmatch || !hashmatch) {

-		ret = SSH_ERR_SIGNATURE_INVALID;

-		goto done;

-	}

-	ret = 0;

+

+	ret = sshkey_verify_signature(pkey, hash_alg, data, datalen,

+	    sigbuf, siglen);

+

 done:

-	freezero(decrypted, rsasize);

 	return ret;

 }

diff --git a/sshkey.c b/sshkey.c

index ad1957762..b95ed0b10 100644

--- a/sshkey.c

+++ b/sshkey.c

@@ -358,6 +358,83 @@ sshkey_type_plain(int type)

 }

 #ifdef WITH_OPENSSL

+int

+sshkey_calculate_signature(EVP_PKEY *pkey, int hash_alg, u_char **sigp,

+    int *lenp, const u_char *data, size_t datalen)

+{

+	EVP_MD_CTX *ctx = NULL;

+	u_char *sig = NULL;

+	int ret, slen, len;

+

+	if (sigp == NULL || lenp == NULL) {

+		return SSH_ERR_INVALID_ARGUMENT;

+	}

+

+	slen = EVP_PKEY_size(pkey);

+	if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)

+		return SSH_ERR_INVALID_ARGUMENT;

+

+	len = slen;

+	if ((sig = malloc(slen)) == NULL) {

+		return SSH_ERR_ALLOC_FAIL;

+	}

+

+	if ((ctx = EVP_MD_CTX_new()) == NULL) {

+		ret = SSH_ERR_ALLOC_FAIL;

+		goto error;

+	}

+	if (EVP_SignInit_ex(ctx, ssh_digest_to_md(hash_alg), NULL) <= 0 ||

+	    EVP_SignUpdate(ctx, data, datalen) <= 0 ||

+	    EVP_SignFinal(ctx, sig, &len, pkey) <= 0) {

+		ret = SSH_ERR_LIBCRYPTO_ERROR;

+		goto error;

+	}

+

+	*sigp = sig;

+	*lenp = len;

+	/* Now owned by the caller */

+	sig = NULL;

+	ret = 0;

+

+error:

+	EVP_MD_CTX_free(ctx);

+	free(sig);

+	return ret;

+}

+

+int

+sshkey_verify_signature(EVP_PKEY *pkey, int hash_alg, const u_char *data,

+    size_t datalen, u_char *sigbuf, int siglen)

+{

+	EVP_MD_CTX *ctx = NULL;

+	int ret;

+

+	if ((ctx = EVP_MD_CTX_new()) == NULL) {

+		return SSH_ERR_ALLOC_FAIL;

+	}

+	if (EVP_VerifyInit_ex(ctx, ssh_digest_to_md(hash_alg), NULL) <= 0 ||

+	    EVP_VerifyUpdate(ctx, data, datalen) <= 0) {

+		ret = SSH_ERR_LIBCRYPTO_ERROR;

+		goto done;

+	}

+	ret = EVP_VerifyFinal(ctx, sigbuf, siglen, pkey);

+	switch (ret) {

+	case 1:

+		ret = 0;

+		break;

+	case 0:

+		ret = SSH_ERR_SIGNATURE_INVALID;

+		break;

+	default:

+		ret = SSH_ERR_LIBCRYPTO_ERROR;

+		break;

+	}

+

+done:

+	EVP_MD_CTX_free(ctx);

+	return ret;

+}

+

 /* XXX: these are really begging for a table-driven approach */

 int

 sshkey_curve_name_to_nid(const char *name)

diff --git a/sshkey.h b/sshkey.h

index a91e60436..270901a87 100644

--- a/sshkey.h

+++ b/sshkey.h

@@ -179,6 +179,10 @@ const char	*sshkey_ssh_name(const struct sshkey *);

 const char	*sshkey_ssh_name_plain(const struct sshkey *);

 int		 sshkey_names_valid2(const char *, int);

 char		*sshkey_alg_list(int, int, int, char);

+int		 sshkey_calculate_signature(EVP_PKEY*, int, u_char **,

+    int *, const u_char *, size_t);

+int		 sshkey_verify_signature(EVP_PKEY *, int, const u_char *,

+    size_t, u_char *, int);

 int	 sshkey_from_blob(const u_char *, size_t, struct sshkey **);

 int	 sshkey_fromb(struct sshbuf *, struct sshkey **);