From eb0d8e708a1f958aecd2d6e2ff2450af488d4c2a Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Mon, 15 Jul 2019 13:16:29 +0000
Subject: [PATCH] upstream: support PKCS8 as an optional format for storage of
private keys, enabled via "ssh-keygen -m PKCS8" on operations that save
private keys to disk.
The OpenSSH native key format remains the default, but PKCS8 is a
superior format to PEM if interoperability with non-OpenSSH software
is required, as it may use a less terrible KDF (IIRC PEM uses a single
round of MD5 as a KDF).
adapted from patch by Jakub Jelen via bz3013; ok markus
OpenBSD-Commit-ID: 027824e3bc0b1c243dc5188504526d73a55accb1
---
authfile.c | 6 ++--
ssh-keygen.1 | 9 +++---
ssh-keygen.c | 25 +++++++++--------
sshkey.c | 78 +++++++++++++++++++++++++++++++++++++---------------
sshkey.h | 11 ++++++--
5 files changed, 87 insertions(+), 42 deletions(-)
diff --git a/authfile.c b/authfile.c
index 2166c1689..851c1a8a1 100644
--- a/authfile.c
+++ b/authfile.c
@@ -74,7 +74,7 @@ sshkey_save_private_blob(struct sshbuf *keybuf, const char *filename)
int
sshkey_save_private(struct sshkey *key, const char *filename,
const char *passphrase, const char *comment,
- int force_new_format, const char *new_format_cipher, int new_format_rounds)
+ int format, const char *openssh_format_cipher, int openssh_format_rounds)
{
struct sshbuf *keyblob = NULL;
int r;
@@ -82,7 +82,7 @@ sshkey_save_private(struct sshkey *key, const char *filename,
if ((keyblob = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshkey_private_to_fileblob(key, keyblob, passphrase, comment,
- force_new_format, new_format_cipher, new_format_rounds)) != 0)
+ format, openssh_format_cipher, openssh_format_rounds)) != 0)
goto out;
if ((r = sshkey_save_private_blob(keyblob, filename)) != 0)
goto out;
diff --git a/ssh-keygen.1 b/ssh-keygen.1
index f42127c60..8184a1797 100644
--- a/ssh-keygen.1
+++ b/ssh-keygen.1
@@ -419,11 +419,12 @@ The supported key formats are:
.Dq RFC4716
(RFC 4716/SSH2 public or private key),
.Dq PKCS8
-(PEM PKCS8 public key)
+(PKCS8 public or private key)
or
.Dq PEM
(PEM public key).
-The default conversion format is
+By default OpenSSH will write newly-generated private keys in its own
+format, but when converting public keys for export the default format is
.Dq RFC4716 .
Setting a format of
.Dq PEM
diff --git a/ssh-keygen.c b/ssh-keygen.c
index b019a02ff..5dcad1f61 100644
--- a/ssh-keygen.c
+++ b/ssh-keygen.c
@@ -147,11 +147,11 @@ static char *key_type_name = NULL;
/* Load key from this PKCS#11 provider */
static char *pkcs11provider = NULL;
-/* Use new OpenSSH private key format when writing SSH2 keys instead of PEM */
-static int use_new_format = 1;
+/* Format for writing private keys */
+static int private_key_format = SSHKEY_PRIVATE_OPENSSH;
/* Cipher for new-format private keys */
-static char *new_format_cipher = NULL;
+static char *openssh_format_cipher = NULL;
/*
* Number of KDF rounds to derive new format keys /
@@ -1048,7 +1048,8 @@ do_gen_all_hostkeys(struct passwd *pw)
snprintf(comment, sizeof comment, "%s@%s", pw->pw_name,
hostname);
if ((r = sshkey_save_private(private, prv_tmp, "",
- comment, use_new_format, new_format_cipher, rounds)) != 0) {
+ comment, private_key_format, openssh_format_cipher,
+ rounds)) != 0) {
error("Saving key \"%s\" failed: %s",
prv_tmp, ssh_err(r));
goto failnext;
@@ -1391,7 +1392,7 @@ do_change_passphrase(struct passwd *pw)
/* Save the file using the new passphrase. */
if ((r = sshkey_save_private(private, identity_file, passphrase1,
- comment, use_new_format, new_format_cipher, rounds)) != 0) {
+ comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
error("Saving key \"%s\" failed: %s.",
identity_file, ssh_err(r));
explicit_bzero(passphrase1, strlen(passphrase1));
@@ -1480,7 +1481,7 @@ do_change_comment(struct passwd *pw, const char *identity_comment)
}
if (private->type != KEY_ED25519 && private->type != KEY_XMSS &&
- !use_new_format) {
+ private_key_format != SSHKEY_PRIVATE_OPENSSH) {
error("Comments are only supported for keys stored in "
"the new format (-o).");
explicit_bzero(passphrase, strlen(passphrase));
@@ -1514,7 +1515,8 @@ do_change_comment(struct passwd *pw, const char *identity_comment)
/* Save the file using the new passphrase. */
if ((r = sshkey_save_private(private, identity_file, passphrase,
- new_comment, use_new_format, new_format_cipher, rounds)) != 0) {
+ new_comment, private_key_format, openssh_format_cipher,
+ rounds)) != 0) {
error("Saving key \"%s\" failed: %s",
identity_file, ssh_err(r));
explicit_bzero(passphrase, strlen(passphrase));
@@ -2525,11 +2527,12 @@ main(int argc, char **argv)
}
if (strcasecmp(optarg, "PKCS8") == 0) {
convert_format = FMT_PKCS8;
+ private_key_format = SSHKEY_PRIVATE_PKCS8;
break;
}
if (strcasecmp(optarg, "PEM") == 0) {
convert_format = FMT_PEM;
- use_new_format = 0;
+ private_key_format = SSHKEY_PRIVATE_PEM;
break;
}
fatal("Unsupported conversion format \"%s\"", optarg);
@@ -2567,7 +2570,7 @@ main(int argc, char **argv)
add_cert_option(optarg);
break;
case 'Z':
- new_format_cipher = optarg;
+ openssh_format_cipher = optarg;
break;
case 'C':
identity_comment = optarg;
@@ -2912,7 +2915,7 @@ main(int argc, char **argv)
/* Save the key with the given passphrase and comment. */
if ((r = sshkey_save_private(private, identity_file, passphrase1,
- comment, use_new_format, new_format_cipher, rounds)) != 0) {
+ comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
error("Saving key \"%s\" failed: %s",
identity_file, ssh_err(r));
explicit_bzero(passphrase1, strlen(passphrase1));
diff --git a/sshkey.c b/sshkey.c
index 6b5ff0485..a0cea9257 100644
--- a/sshkey.c
+++ b/sshkey.c
@@ -3975,10 +3975,10 @@ sshkey_parse_private2(struct sshbuf *blob, int type, const char *passphrase,
#ifdef WITH_OPENSSL
-/* convert SSH v2 key in OpenSSL PEM format */
+/* convert SSH v2 key to PEM or PKCS#8 format */
static int
-sshkey_private_pem_to_blob(struct sshkey *key, struct sshbuf *blob,
- const char *_passphrase, const char *comment)
+sshkey_private_to_blob_pem_pkcs8(struct sshkey *key, struct sshbuf *blob,
+ int format, const char *_passphrase, const char *comment)
{
int success, r;
int blen, len = strlen(_passphrase);
@@ -3988,26 +3988,46 @@ sshkey_private_pem_to_blob(struct sshkey *key, struct sshbuf *buf,
const EVP_CIPHER *cipher = (len > 0) ? EVP_aes_128_cbc() : NULL;
char *bptr;
BIO *bio = NULL;
+ EVP_PKEY *pkey = NULL;
if (len > 0 && len <= 4)
return SSH_ERR_PASSPHRASE_TOO_SHORT;
- if ((bio = BIO_new(BIO_s_mem())) == NULL)
- return SSH_ERR_ALLOC_FAIL;
+ if ((bio = BIO_new(BIO_s_mem())) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+
+ if (format == SSHKEY_PRIVATE_PKCS8 && (pkey = EVP_PKEY_new()) == NULL) {
+ r = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
switch (key->type) {
case KEY_DSA:
- success = PEM_write_bio_DSAPrivateKey(bio, key->dsa,
- cipher, passphrase, len, NULL, NULL);
+ if (format == SSHKEY_PRIVATE_PEM) {
+ success = PEM_write_bio_DSAPrivateKey(bio, key->dsa,
+ cipher, passphrase, len, NULL, NULL);
+ } else {
+ success = EVP_PKEY_set1_DSA(pkey, key->dsa);
+ }
break;
#ifdef OPENSSL_HAS_ECC
case KEY_ECDSA:
- success = PEM_write_bio_ECPrivateKey(bio, key->ecdsa,
- cipher, passphrase, len, NULL, NULL);
+ if (format == SSHKEY_PRIVATE_PEM) {
+ success = PEM_write_bio_ECPrivateKey(bio, key->ecdsa,
+ cipher, passphrase, len, NULL, NULL);
+ } else {
+ success = EVP_PKEY_set1_EC_KEY(pkey, key->ecdsa);
+ }
break;
#endif
case KEY_RSA:
- success = PEM_write_bio_RSAPrivateKey(bio, key->rsa,
- cipher, passphrase, len, NULL, NULL);
+ if (format == SSHKEY_PRIVATE_PEM) {
+ success = PEM_write_bio_RSAPrivateKey(bio, key->rsa,
+ cipher, passphrase, len, NULL, NULL);
+ } else {
+ success = EVP_PKEY_set1_RSA(pkey, key->rsa);
+ }
break;
default:
success = 0;
@@ -4023,6 +4040,13 @@ sshkey_private_pem_to_blob(struct sshkey *key, struct sshbuf *buf,
r = SSH_ERR_LIBCRYPTO_ERROR;
goto out;
}
+ if (format == SSHKEY_PRIVATE_PKCS8) {
+ if ((success = PEM_write_bio_PrivateKey(bio, pkey, cipher,
+ passphrase, len, NULL, NULL)) == 0) {
+ r = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ }
if ((blen = BIO_get_mem_data(bio, &bptr)) <= 0) {
r = SSH_ERR_INTERNAL_ERROR;
goto out;
@@ -4035,6 +4059,7 @@ sshkey_private_pem_to_blob(struct sshkey *key, struct sshbuf *buf,
goto out;
r = 0;
out:
+ EVP_PKEY_free(pkey);
BIO_free(bio);
return r;
}
@@ -4046,29 +4071,38 @@ sshkey_private_pem_to_blob(struct sshkey *key, struct sshbuf *buf,
int
sshkey_private_to_fileblob(struct sshkey *key, struct sshbuf *blob,
const char *passphrase, const char *comment,
- int force_new_format, const char *new_format_cipher, int new_format_rounds)
+ int format, const char *openssh_format_cipher, int openssh_format_rounds)
{
switch (key->type) {
#ifdef WITH_OPENSSL
case KEY_DSA:
case KEY_ECDSA:
case KEY_RSA:
- if (force_new_format) {
- return sshkey_private_to_blob2(key, blob, passphrase,
- comment, new_format_cipher, new_format_rounds);
- }
- return sshkey_private_pem_to_blob(key, blob,
- passphrase, comment);
+ break; /* see below */
#endif /* WITH_OPENSSL */
case KEY_ED25519:
#ifdef WITH_XMSS
case KEY_XMSS:
#endif /* WITH_XMSS */
return sshkey_private_to_blob2(key, blob, passphrase,
- comment, new_format_cipher, new_format_rounds);
+ comment, openssh_format_cipher, openssh_format_rounds);
default:
return SSH_ERR_KEY_TYPE_UNKNOWN;
}
+
+#ifdef WITH_OPENSSL
+ switch (format) {
+ case SSHKEY_PRIVATE_OPENSSH:
+ return sshkey_private_to_blob2(key, blob, passphrase,
+ comment, openssh_format_cipher, openssh_format_rounds);
+ case SSHKEY_PRIVATE_PEM:
+ case SSHKEY_PRIVATE_PKCS8:
+ return sshkey_private_to_blob_pem_pkcs8(key, blob,
+ format, passphrase, comment);
+ default:
+ return SSH_ERR_INVALID_ARGUMENT;
+ }
+#endif /* WITH_OPENSSL */
}
diff --git a/sshkey.h b/sshkey.h
index 41d159a1b..d30a69cc9 100644
--- a/sshkey.h
+++ b/sshkey.h
@@ -88,6 +88,13 @@ enum sshkey_serialize_rep {
SSHKEY_SERIALIZE_INFO = 254,
};
+/* Private key disk formats */
+enum sshkey_private_format {
+ SSHKEY_PRIVATE_OPENSSH = 0,
+ SSHKEY_PRIVATE_PEM = 1,
+ SSHKEY_PRIVATE_PKCS8 = 2,
+};
+
/* key is stored in external hardware */
#define SSHKEY_FLAG_EXT 0x0001
@@ -221,7 +228,7 @@ int sshkey_private_deserialize(struct sshbuf *buf, struct sshkey **keyp);
/* private key file format parsing and serialisation */
int sshkey_private_to_fileblob(struct sshkey *key, struct sshbuf *blob,
const char *passphrase, const char *comment,
- int force_new_format, const char *new_format_cipher, int new_format_rounds);
+ int format, const char *openssh_format_cipher, int openssh_format_rounds);
int sshkey_parse_private_fileblob(struct sshbuf *buffer,
const char *passphrase, struct sshkey **keyp, char **commentp);
int sshkey_parse_private_fileblob_type(struct sshbuf *blob, int type,