1 /* $OpenBSD: ssh-rsa.c,v 1.60 2016/09/12 23:39:34 djm Exp $ */
3 * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22 #include <sys/types.h>
24 #include <openssl/evp.h>
25 #include <openssl/err.h>
33 #define SSHKEY_INTERNAL
37 static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *);
40 rsa_hash_alg_ident(int hash_alg)
45 case SSH_DIGEST_SHA256:
46 return "rsa-sha2-256";
47 case SSH_DIGEST_SHA512:
48 return "rsa-sha2-512";
54 rsa_hash_alg_from_ident(const char *ident)
56 if (strcmp(ident, "ssh-rsa") == 0 ||
57 strcmp(ident, "ssh-rsa-cert-v01@openssh.com") == 0)
58 return SSH_DIGEST_SHA1;
59 if (strcmp(ident, "rsa-sha2-256") == 0)
60 return SSH_DIGEST_SHA256;
61 if (strcmp(ident, "rsa-sha2-512") == 0)
62 return SSH_DIGEST_SHA512;
67 rsa_hash_alg_nid(int type)
72 case SSH_DIGEST_SHA256:
74 case SSH_DIGEST_SHA512:
81 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
83 ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
84 const u_char *data, size_t datalen, const char *alg_ident)
86 u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL;
89 int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
90 struct sshbuf *b = NULL;
97 if (alg_ident == NULL || strlen(alg_ident) == 0)
98 hash_alg = SSH_DIGEST_SHA1;
100 hash_alg = rsa_hash_alg_from_ident(alg_ident);
101 if (key == NULL || key->rsa == NULL || hash_alg == -1 ||
102 sshkey_type_plain(key->type) != KEY_RSA ||
103 BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
104 return SSH_ERR_INVALID_ARGUMENT;
105 slen = RSA_size(key->rsa);
106 if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)
107 return SSH_ERR_INVALID_ARGUMENT;
110 nid = rsa_hash_alg_nid(hash_alg);
111 if ((dlen = ssh_digest_bytes(hash_alg)) == 0)
112 return SSH_ERR_INTERNAL_ERROR;
113 if ((ret = ssh_digest_memory(hash_alg, data, datalen,
114 digest, sizeof(digest))) != 0)
117 if ((sig = malloc(slen)) == NULL) {
118 ret = SSH_ERR_ALLOC_FAIL;
122 if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) {
123 ret = SSH_ERR_LIBCRYPTO_ERROR;
127 size_t diff = slen - len;
128 memmove(sig + diff, sig, len);
129 explicit_bzero(sig, diff);
130 } else if (len > slen) {
131 ret = SSH_ERR_INTERNAL_ERROR;
134 /* encode signature */
135 if ((b = sshbuf_new()) == NULL) {
136 ret = SSH_ERR_ALLOC_FAIL;
139 if ((ret = sshbuf_put_cstring(b, rsa_hash_alg_ident(hash_alg))) != 0 ||
140 (ret = sshbuf_put_string(b, sig, slen)) != 0)
144 if ((*sigp = malloc(len)) == NULL) {
145 ret = SSH_ERR_ALLOC_FAIL;
148 memcpy(*sigp, sshbuf_ptr(b), len);
154 explicit_bzero(digest, sizeof(digest));
156 explicit_bzero(sig, slen);
164 ssh_rsa_verify(const struct sshkey *key,
165 const u_char *sig, size_t siglen, const u_char *data, size_t datalen)
168 int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
169 size_t len, diff, modlen, dlen;
170 struct sshbuf *b = NULL;
171 u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL;
173 if (key == NULL || key->rsa == NULL ||
174 sshkey_type_plain(key->type) != KEY_RSA ||
175 BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE ||
176 sig == NULL || siglen == 0)
177 return SSH_ERR_INVALID_ARGUMENT;
179 if ((b = sshbuf_from(sig, siglen)) == NULL)
180 return SSH_ERR_ALLOC_FAIL;
181 if (sshbuf_get_cstring(b, &ktype, NULL) != 0) {
182 ret = SSH_ERR_INVALID_FORMAT;
185 if ((hash_alg = rsa_hash_alg_from_ident(ktype)) == -1) {
186 ret = SSH_ERR_KEY_TYPE_MISMATCH;
189 if (sshbuf_get_string(b, &sigblob, &len) != 0) {
190 ret = SSH_ERR_INVALID_FORMAT;
193 if (sshbuf_len(b) != 0) {
194 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
197 /* RSA_verify expects a signature of RSA_size */
198 modlen = RSA_size(key->rsa);
200 ret = SSH_ERR_KEY_BITS_MISMATCH;
202 } else if (len < modlen) {
205 if ((sigblob = realloc(sigblob, modlen)) == NULL) {
206 sigblob = osigblob; /* put it back for clear/free */
207 ret = SSH_ERR_ALLOC_FAIL;
210 memmove(sigblob + diff, sigblob, len);
211 explicit_bzero(sigblob, diff);
214 if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
215 ret = SSH_ERR_INTERNAL_ERROR;
218 if ((ret = ssh_digest_memory(hash_alg, data, datalen,
219 digest, sizeof(digest))) != 0)
222 ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
225 if (sigblob != NULL) {
226 explicit_bzero(sigblob, len);
231 explicit_bzero(digest, sizeof(digest));
237 * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
238 * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
242 * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
243 * oiw(14) secsig(3) algorithms(2) 26 }
245 static const u_char id_sha1[] = {
246 0x30, 0x21, /* type Sequence, length 0x21 (33) */
247 0x30, 0x09, /* type Sequence, length 0x09 */
248 0x06, 0x05, /* type OID, length 0x05 */
249 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
250 0x05, 0x00, /* NULL */
251 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */
255 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
256 * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
257 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
260 static const u_char id_sha256[] = {
261 0x30, 0x31, /* type Sequence, length 0x31 (49) */
262 0x30, 0x0d, /* type Sequence, length 0x0d (13) */
263 0x06, 0x09, /* type OID, length 0x09 */
264 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */
265 0x05, 0x00, /* NULL */
266 0x04, 0x20 /* Octet string, length 0x20 (32), followed by sha256 hash */
270 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
271 * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
272 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
275 static const u_char id_sha512[] = {
276 0x30, 0x51, /* type Sequence, length 0x51 (81) */
277 0x30, 0x0d, /* type Sequence, length 0x0d (13) */
278 0x06, 0x09, /* type OID, length 0x09 */
279 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */
280 0x05, 0x00, /* NULL */
281 0x04, 0x40 /* Octet string, length 0x40 (64), followed by sha512 hash */
285 rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp)
288 case SSH_DIGEST_SHA1:
290 *oidlenp = sizeof(id_sha1);
292 case SSH_DIGEST_SHA256:
294 *oidlenp = sizeof(id_sha256);
296 case SSH_DIGEST_SHA512:
298 *oidlenp = sizeof(id_sha512);
301 return SSH_ERR_INVALID_ARGUMENT;
307 openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
308 u_char *sigbuf, size_t siglen, RSA *rsa)
310 size_t rsasize = 0, oidlen = 0, hlen = 0;
311 int ret, len, oidmatch, hashmatch;
312 const u_char *oid = NULL;
313 u_char *decrypted = NULL;
315 if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0)
317 ret = SSH_ERR_INTERNAL_ERROR;
318 hlen = ssh_digest_bytes(hash_alg);
319 if (hashlen != hlen) {
320 ret = SSH_ERR_INVALID_ARGUMENT;
323 rsasize = RSA_size(rsa);
324 if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM ||
325 siglen == 0 || siglen > rsasize) {
326 ret = SSH_ERR_INVALID_ARGUMENT;
329 if ((decrypted = malloc(rsasize)) == NULL) {
330 ret = SSH_ERR_ALLOC_FAIL;
333 if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
334 RSA_PKCS1_PADDING)) < 0) {
335 ret = SSH_ERR_LIBCRYPTO_ERROR;
338 if (len < 0 || (size_t)len != hlen + oidlen) {
339 ret = SSH_ERR_INVALID_FORMAT;
342 oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
343 hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
344 if (!oidmatch || !hashmatch) {
345 ret = SSH_ERR_SIGNATURE_INVALID;
351 explicit_bzero(decrypted, rsasize);
356 #endif /* WITH_OPENSSL */