1 /* $OpenBSD: ssh-rsa.c,v 1.66 2018/02/14 16:27:24 jsing 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
38 static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *);
41 rsa_hash_alg_ident(int hash_alg)
46 case SSH_DIGEST_SHA256:
47 return "rsa-sha2-256";
48 case SSH_DIGEST_SHA512:
49 return "rsa-sha2-512";
55 rsa_hash_alg_from_ident(const char *ident)
57 if (strcmp(ident, "ssh-rsa") == 0 ||
58 strcmp(ident, "ssh-rsa-cert-v01@openssh.com") == 0)
59 return SSH_DIGEST_SHA1;
60 if (strcmp(ident, "rsa-sha2-256") == 0)
61 return SSH_DIGEST_SHA256;
62 if (strcmp(ident, "rsa-sha2-512") == 0)
63 return SSH_DIGEST_SHA512;
68 rsa_hash_alg_nid(int type)
73 case SSH_DIGEST_SHA256:
75 case SSH_DIGEST_SHA512:
83 ssh_rsa_generate_additional_parameters(struct sshkey *key)
90 if (key == NULL || key->rsa == NULL ||
91 sshkey_type_plain(key->type) != KEY_RSA)
92 return SSH_ERR_INVALID_ARGUMENT;
94 if ((ctx = BN_CTX_new()) == NULL)
95 return SSH_ERR_ALLOC_FAIL;
96 if ((aux = BN_new()) == NULL) {
97 r = SSH_ERR_ALLOC_FAIL;
100 BN_set_flags(aux, BN_FLG_CONSTTIME);
103 BN_with_flags(&d, key->rsa->d, BN_FLG_CONSTTIME);
105 if ((BN_sub(aux, key->rsa->q, BN_value_one()) == 0) ||
106 (BN_mod(key->rsa->dmq1, &d, aux, ctx) == 0) ||
107 (BN_sub(aux, key->rsa->p, BN_value_one()) == 0) ||
108 (BN_mod(key->rsa->dmp1, &d, aux, ctx) == 0)) {
109 r = SSH_ERR_LIBCRYPTO_ERROR;
119 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
121 ssh_rsa_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
122 const u_char *data, size_t datalen, const char *alg_ident)
124 u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL;
127 int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
128 struct sshbuf *b = NULL;
135 if (alg_ident == NULL || strlen(alg_ident) == 0)
136 hash_alg = SSH_DIGEST_SHA1;
138 hash_alg = rsa_hash_alg_from_ident(alg_ident);
139 if (key == NULL || key->rsa == NULL || hash_alg == -1 ||
140 sshkey_type_plain(key->type) != KEY_RSA)
141 return SSH_ERR_INVALID_ARGUMENT;
142 if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
143 return SSH_ERR_KEY_LENGTH;
144 slen = RSA_size(key->rsa);
145 if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)
146 return SSH_ERR_INVALID_ARGUMENT;
149 nid = rsa_hash_alg_nid(hash_alg);
150 if ((dlen = ssh_digest_bytes(hash_alg)) == 0)
151 return SSH_ERR_INTERNAL_ERROR;
152 if ((ret = ssh_digest_memory(hash_alg, data, datalen,
153 digest, sizeof(digest))) != 0)
156 if ((sig = malloc(slen)) == NULL) {
157 ret = SSH_ERR_ALLOC_FAIL;
161 if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) {
162 ret = SSH_ERR_LIBCRYPTO_ERROR;
166 size_t diff = slen - len;
167 memmove(sig + diff, sig, len);
168 explicit_bzero(sig, diff);
169 } else if (len > slen) {
170 ret = SSH_ERR_INTERNAL_ERROR;
173 /* encode signature */
174 if ((b = sshbuf_new()) == NULL) {
175 ret = SSH_ERR_ALLOC_FAIL;
178 if ((ret = sshbuf_put_cstring(b, rsa_hash_alg_ident(hash_alg))) != 0 ||
179 (ret = sshbuf_put_string(b, sig, slen)) != 0)
183 if ((*sigp = malloc(len)) == NULL) {
184 ret = SSH_ERR_ALLOC_FAIL;
187 memcpy(*sigp, sshbuf_ptr(b), len);
193 explicit_bzero(digest, sizeof(digest));
200 ssh_rsa_verify(const struct sshkey *key,
201 const u_char *sig, size_t siglen, const u_char *data, size_t datalen,
204 char *sigtype = NULL;
205 int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
206 size_t len = 0, diff, modlen, dlen;
207 struct sshbuf *b = NULL;
208 u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL;
210 if (key == NULL || key->rsa == NULL ||
211 sshkey_type_plain(key->type) != KEY_RSA ||
212 sig == NULL || siglen == 0)
213 return SSH_ERR_INVALID_ARGUMENT;
214 if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
215 return SSH_ERR_KEY_LENGTH;
217 if ((b = sshbuf_from(sig, siglen)) == NULL)
218 return SSH_ERR_ALLOC_FAIL;
219 if (sshbuf_get_cstring(b, &sigtype, NULL) != 0) {
220 ret = SSH_ERR_INVALID_FORMAT;
223 /* XXX djm: need cert types that reliably yield SHA-2 signatures */
224 if (alg != NULL && strcmp(alg, sigtype) != 0 &&
225 strcmp(alg, "ssh-rsa-cert-v01@openssh.com") != 0) {
226 error("%s: RSA signature type mismatch: "
227 "expected %s received %s", __func__, alg, sigtype);
228 ret = SSH_ERR_SIGNATURE_INVALID;
231 if ((hash_alg = rsa_hash_alg_from_ident(sigtype)) == -1) {
232 ret = SSH_ERR_KEY_TYPE_MISMATCH;
235 if (sshbuf_get_string(b, &sigblob, &len) != 0) {
236 ret = SSH_ERR_INVALID_FORMAT;
239 if (sshbuf_len(b) != 0) {
240 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
243 /* RSA_verify expects a signature of RSA_size */
244 modlen = RSA_size(key->rsa);
246 ret = SSH_ERR_KEY_BITS_MISMATCH;
248 } else if (len < modlen) {
251 if ((sigblob = realloc(sigblob, modlen)) == NULL) {
252 sigblob = osigblob; /* put it back for clear/free */
253 ret = SSH_ERR_ALLOC_FAIL;
256 memmove(sigblob + diff, sigblob, len);
257 explicit_bzero(sigblob, diff);
260 if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
261 ret = SSH_ERR_INTERNAL_ERROR;
264 if ((ret = ssh_digest_memory(hash_alg, data, datalen,
265 digest, sizeof(digest))) != 0)
268 ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
271 freezero(sigblob, len);
274 explicit_bzero(digest, sizeof(digest));
280 * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
281 * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
285 * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
286 * oiw(14) secsig(3) algorithms(2) 26 }
288 static const u_char id_sha1[] = {
289 0x30, 0x21, /* type Sequence, length 0x21 (33) */
290 0x30, 0x09, /* type Sequence, length 0x09 */
291 0x06, 0x05, /* type OID, length 0x05 */
292 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
293 0x05, 0x00, /* NULL */
294 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */
298 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
299 * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
300 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
303 static const u_char id_sha256[] = {
304 0x30, 0x31, /* type Sequence, length 0x31 (49) */
305 0x30, 0x0d, /* type Sequence, length 0x0d (13) */
306 0x06, 0x09, /* type OID, length 0x09 */
307 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */
308 0x05, 0x00, /* NULL */
309 0x04, 0x20 /* Octet string, length 0x20 (32), followed by sha256 hash */
313 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html
314 * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840)
315 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2)
318 static const u_char id_sha512[] = {
319 0x30, 0x51, /* type Sequence, length 0x51 (81) */
320 0x30, 0x0d, /* type Sequence, length 0x0d (13) */
321 0x06, 0x09, /* type OID, length 0x09 */
322 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */
323 0x05, 0x00, /* NULL */
324 0x04, 0x40 /* Octet string, length 0x40 (64), followed by sha512 hash */
328 rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp)
331 case SSH_DIGEST_SHA1:
333 *oidlenp = sizeof(id_sha1);
335 case SSH_DIGEST_SHA256:
337 *oidlenp = sizeof(id_sha256);
339 case SSH_DIGEST_SHA512:
341 *oidlenp = sizeof(id_sha512);
344 return SSH_ERR_INVALID_ARGUMENT;
350 openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
351 u_char *sigbuf, size_t siglen, RSA *rsa)
353 size_t rsasize = 0, oidlen = 0, hlen = 0;
354 int ret, len, oidmatch, hashmatch;
355 const u_char *oid = NULL;
356 u_char *decrypted = NULL;
358 if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0)
360 ret = SSH_ERR_INTERNAL_ERROR;
361 hlen = ssh_digest_bytes(hash_alg);
362 if (hashlen != hlen) {
363 ret = SSH_ERR_INVALID_ARGUMENT;
366 rsasize = RSA_size(rsa);
367 if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM ||
368 siglen == 0 || siglen > rsasize) {
369 ret = SSH_ERR_INVALID_ARGUMENT;
372 if ((decrypted = malloc(rsasize)) == NULL) {
373 ret = SSH_ERR_ALLOC_FAIL;
376 if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
377 RSA_PKCS1_PADDING)) < 0) {
378 ret = SSH_ERR_LIBCRYPTO_ERROR;
381 if (len < 0 || (size_t)len != hlen + oidlen) {
382 ret = SSH_ERR_INVALID_FORMAT;
385 oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
386 hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
387 if (!oidmatch || !hashmatch) {
388 ret = SSH_ERR_SIGNATURE_INVALID;
393 freezero(decrypted, rsasize);
396 #endif /* WITH_OPENSSL */