1 /* $OpenBSD: ssh-dss.c,v 1.48 2022/10/28 00:44:44 djm Exp $ */
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 #include <sys/types.h>
32 #include <openssl/bn.h>
33 #include <openssl/dsa.h>
34 #include <openssl/evp.h>
43 #define SSHKEY_INTERNAL
46 #include "openbsd-compat/openssl-compat.h"
48 #define INTBLOB_LEN 20
49 #define SIGBLOB_LEN (2*INTBLOB_LEN)
52 ssh_dss_size(const struct sshkey *key)
58 DSA_get0_pqg(key->dsa, &dsa_p, NULL, NULL);
59 return BN_num_bits(dsa_p);
63 ssh_dss_alloc(struct sshkey *k)
65 if ((k->dsa = DSA_new()) == NULL)
66 return SSH_ERR_ALLOC_FAIL;
71 ssh_dss_cleanup(struct sshkey *k)
78 ssh_dss_equal(const struct sshkey *a, const struct sshkey *b)
80 const BIGNUM *dsa_p_a, *dsa_q_a, *dsa_g_a, *dsa_pub_key_a;
81 const BIGNUM *dsa_p_b, *dsa_q_b, *dsa_g_b, *dsa_pub_key_b;
83 if (a->dsa == NULL || b->dsa == NULL)
85 DSA_get0_pqg(a->dsa, &dsa_p_a, &dsa_q_a, &dsa_g_a);
86 DSA_get0_pqg(b->dsa, &dsa_p_b, &dsa_q_b, &dsa_g_b);
87 DSA_get0_key(a->dsa, &dsa_pub_key_a, NULL);
88 DSA_get0_key(b->dsa, &dsa_pub_key_b, NULL);
89 if (dsa_p_a == NULL || dsa_p_b == NULL ||
90 dsa_q_a == NULL || dsa_q_b == NULL ||
91 dsa_g_a == NULL || dsa_g_b == NULL ||
92 dsa_pub_key_a == NULL || dsa_pub_key_b == NULL)
94 if (BN_cmp(dsa_p_a, dsa_p_b) != 0)
96 if (BN_cmp(dsa_q_a, dsa_q_b) != 0)
98 if (BN_cmp(dsa_g_a, dsa_g_b) != 0)
100 if (BN_cmp(dsa_pub_key_a, dsa_pub_key_b) != 0)
106 ssh_dss_serialize_public(const struct sshkey *key, struct sshbuf *b,
107 enum sshkey_serialize_rep opts)
110 const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
112 if (key->dsa == NULL)
113 return SSH_ERR_INVALID_ARGUMENT;
114 DSA_get0_pqg(key->dsa, &dsa_p, &dsa_q, &dsa_g);
115 DSA_get0_key(key->dsa, &dsa_pub_key, NULL);
116 if (dsa_p == NULL || dsa_q == NULL ||
117 dsa_g == NULL || dsa_pub_key == NULL)
118 return SSH_ERR_INTERNAL_ERROR;
119 if ((r = sshbuf_put_bignum2(b, dsa_p)) != 0 ||
120 (r = sshbuf_put_bignum2(b, dsa_q)) != 0 ||
121 (r = sshbuf_put_bignum2(b, dsa_g)) != 0 ||
122 (r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0)
129 ssh_dss_serialize_private(const struct sshkey *key, struct sshbuf *b,
130 enum sshkey_serialize_rep opts)
133 const BIGNUM *dsa_priv_key;
135 DSA_get0_key(key->dsa, NULL, &dsa_priv_key);
136 if (!sshkey_is_cert(key)) {
137 if ((r = ssh_dss_serialize_public(key, b, opts)) != 0)
140 if ((r = sshbuf_put_bignum2(b, dsa_priv_key)) != 0)
147 ssh_dss_generate(struct sshkey *k, int bits)
152 return SSH_ERR_KEY_LENGTH;
153 if ((private = DSA_new()) == NULL)
154 return SSH_ERR_ALLOC_FAIL;
155 if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL,
156 NULL, NULL) || !DSA_generate_key(private)) {
158 return SSH_ERR_LIBCRYPTO_ERROR;
165 ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to)
167 const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
168 BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
169 BIGNUM *dsa_pub_key_dup = NULL;
170 int r = SSH_ERR_INTERNAL_ERROR;
172 DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g);
173 DSA_get0_key(from->dsa, &dsa_pub_key, NULL);
174 if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
175 (dsa_q_dup = BN_dup(dsa_q)) == NULL ||
176 (dsa_g_dup = BN_dup(dsa_g)) == NULL ||
177 (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
178 r = SSH_ERR_ALLOC_FAIL;
181 if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
182 r = SSH_ERR_LIBCRYPTO_ERROR;
185 dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
186 if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) {
187 r = SSH_ERR_LIBCRYPTO_ERROR;
190 dsa_pub_key_dup = NULL; /* transferred */
194 BN_clear_free(dsa_p_dup);
195 BN_clear_free(dsa_q_dup);
196 BN_clear_free(dsa_g_dup);
197 BN_clear_free(dsa_pub_key_dup);
202 ssh_dss_deserialize_public(const char *ktype, struct sshbuf *b,
205 int ret = SSH_ERR_INTERNAL_ERROR;
206 BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL, *dsa_pub_key = NULL;
208 if (sshbuf_get_bignum2(b, &dsa_p) != 0 ||
209 sshbuf_get_bignum2(b, &dsa_q) != 0 ||
210 sshbuf_get_bignum2(b, &dsa_g) != 0 ||
211 sshbuf_get_bignum2(b, &dsa_pub_key) != 0) {
212 ret = SSH_ERR_INVALID_FORMAT;
215 if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g)) {
216 ret = SSH_ERR_LIBCRYPTO_ERROR;
219 dsa_p = dsa_q = dsa_g = NULL; /* transferred */
220 if (!DSA_set0_key(key->dsa, dsa_pub_key, NULL)) {
221 ret = SSH_ERR_LIBCRYPTO_ERROR;
224 dsa_pub_key = NULL; /* transferred */
226 DSA_print_fp(stderr, key->dsa, 8);
231 BN_clear_free(dsa_p);
232 BN_clear_free(dsa_q);
233 BN_clear_free(dsa_g);
234 BN_clear_free(dsa_pub_key);
239 ssh_dss_deserialize_private(const char *ktype, struct sshbuf *b,
243 BIGNUM *dsa_priv_key = NULL;
245 if (!sshkey_is_cert(key)) {
246 if ((r = ssh_dss_deserialize_public(ktype, b, key)) != 0)
250 if ((r = sshbuf_get_bignum2(b, &dsa_priv_key)) != 0)
252 if (!DSA_set0_key(key->dsa, NULL, dsa_priv_key)) {
253 BN_clear_free(dsa_priv_key);
254 return SSH_ERR_LIBCRYPTO_ERROR;
260 ssh_dss_sign(struct sshkey *key,
261 u_char **sigp, size_t *lenp,
262 const u_char *data, size_t datalen,
263 const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
266 const BIGNUM *sig_r, *sig_s;
267 u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
268 size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
269 struct sshbuf *b = NULL;
270 int ret = SSH_ERR_INVALID_ARGUMENT;
277 if (key == NULL || key->dsa == NULL ||
278 sshkey_type_plain(key->type) != KEY_DSA)
279 return SSH_ERR_INVALID_ARGUMENT;
281 return SSH_ERR_INTERNAL_ERROR;
283 if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
284 digest, sizeof(digest))) != 0)
287 if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
288 ret = SSH_ERR_LIBCRYPTO_ERROR;
292 DSA_SIG_get0(sig, &sig_r, &sig_s);
293 rlen = BN_num_bytes(sig_r);
294 slen = BN_num_bytes(sig_s);
295 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
296 ret = SSH_ERR_INTERNAL_ERROR;
299 explicit_bzero(sigblob, SIGBLOB_LEN);
300 BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
301 BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
303 if ((b = sshbuf_new()) == NULL) {
304 ret = SSH_ERR_ALLOC_FAIL;
307 if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
308 (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
313 if ((*sigp = malloc(len)) == NULL) {
314 ret = SSH_ERR_ALLOC_FAIL;
317 memcpy(*sigp, sshbuf_ptr(b), len);
323 explicit_bzero(digest, sizeof(digest));
330 ssh_dss_verify(const struct sshkey *key,
331 const u_char *sig, size_t siglen,
332 const u_char *data, size_t dlen, const char *alg, u_int compat,
333 struct sshkey_sig_details **detailsp)
335 DSA_SIG *dsig = NULL;
336 BIGNUM *sig_r = NULL, *sig_s = NULL;
337 u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
338 size_t len, hlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
339 int ret = SSH_ERR_INTERNAL_ERROR;
340 struct sshbuf *b = NULL;
343 if (key == NULL || key->dsa == NULL ||
344 sshkey_type_plain(key->type) != KEY_DSA ||
345 sig == NULL || siglen == 0)
346 return SSH_ERR_INVALID_ARGUMENT;
348 return SSH_ERR_INTERNAL_ERROR;
350 /* fetch signature */
351 if ((b = sshbuf_from(sig, siglen)) == NULL)
352 return SSH_ERR_ALLOC_FAIL;
353 if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
354 sshbuf_get_string(b, &sigblob, &len) != 0) {
355 ret = SSH_ERR_INVALID_FORMAT;
358 if (strcmp("ssh-dss", ktype) != 0) {
359 ret = SSH_ERR_KEY_TYPE_MISMATCH;
362 if (sshbuf_len(b) != 0) {
363 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
367 if (len != SIGBLOB_LEN) {
368 ret = SSH_ERR_INVALID_FORMAT;
372 /* parse signature */
373 if ((dsig = DSA_SIG_new()) == NULL ||
374 (sig_r = BN_new()) == NULL ||
375 (sig_s = BN_new()) == NULL) {
376 ret = SSH_ERR_ALLOC_FAIL;
379 if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
380 (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
381 ret = SSH_ERR_LIBCRYPTO_ERROR;
384 if (!DSA_SIG_set0(dsig, sig_r, sig_s)) {
385 ret = SSH_ERR_LIBCRYPTO_ERROR;
388 sig_r = sig_s = NULL; /* transferred */
391 if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, dlen,
392 digest, sizeof(digest))) != 0)
395 switch (DSA_do_verify(digest, hlen, dsig, key->dsa)) {
400 ret = SSH_ERR_SIGNATURE_INVALID;
403 ret = SSH_ERR_LIBCRYPTO_ERROR;
408 explicit_bzero(digest, sizeof(digest));
410 BN_clear_free(sig_r);
411 BN_clear_free(sig_s);
415 freezero(sigblob, len);
419 static const struct sshkey_impl_funcs sshkey_dss_funcs = {
420 /* .size = */ ssh_dss_size,
421 /* .alloc = */ ssh_dss_alloc,
422 /* .cleanup = */ ssh_dss_cleanup,
423 /* .equal = */ ssh_dss_equal,
424 /* .ssh_serialize_public = */ ssh_dss_serialize_public,
425 /* .ssh_deserialize_public = */ ssh_dss_deserialize_public,
426 /* .ssh_serialize_private = */ ssh_dss_serialize_private,
427 /* .ssh_deserialize_private = */ ssh_dss_deserialize_private,
428 /* .generate = */ ssh_dss_generate,
429 /* .copy_public = */ ssh_dss_copy_public,
430 /* .sign = */ ssh_dss_sign,
431 /* .verify = */ ssh_dss_verify,
434 const struct sshkey_impl sshkey_dss_impl = {
435 /* .name = */ "ssh-dss",
436 /* .shortname = */ "DSA",
437 /* .sigalg = */ NULL,
438 /* .type = */ KEY_DSA,
443 /* .funcs = */ &sshkey_dss_funcs,
446 const struct sshkey_impl sshkey_dsa_cert_impl = {
447 /* .name = */ "ssh-dss-cert-v01@openssh.com",
448 /* .shortname = */ "DSA-CERT",
449 /* .sigalg = */ NULL,
450 /* .type = */ KEY_DSA_CERT,
455 /* .funcs = */ &sshkey_dss_funcs,
457 #endif /* WITH_OPENSSL */