Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.44
1.44 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.43 2022/10/28 00:39:29 djm Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
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.
13: *
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.
24: */
25:
1.23 deraadt 26: #include <sys/types.h>
1.4 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/evp.h>
1.22 stevesk 30:
31: #include <string.h>
1.1 markus 32:
1.32 djm 33: #include "sshbuf.h"
1.1 markus 34: #include "compat.h"
1.32 djm 35: #include "ssherr.h"
1.30 djm 36: #include "digest.h"
1.32 djm 37: #define SSHKEY_INTERNAL
38: #include "sshkey.h"
1.1 markus 39:
40: #define INTBLOB_LEN 20
41: #define SIGBLOB_LEN (2*INTBLOB_LEN)
42:
1.40 djm 43: static u_int
44: ssh_dss_size(const struct sshkey *key)
45: {
46: const BIGNUM *dsa_p;
47:
48: if (key->dsa == NULL)
49: return 0;
50: DSA_get0_pqg(key->dsa, &dsa_p, NULL, NULL);
51: return BN_num_bits(dsa_p);
52: }
53:
54: static int
55: ssh_dss_alloc(struct sshkey *k)
56: {
57: if ((k->dsa = DSA_new()) == NULL)
58: return SSH_ERR_ALLOC_FAIL;
59: return 0;
60: }
61:
62: static void
63: ssh_dss_cleanup(struct sshkey *k)
64: {
65: DSA_free(k->dsa);
66: k->dsa = NULL;
67: }
68:
1.41 djm 69: static int
70: ssh_dss_equal(const struct sshkey *a, const struct sshkey *b)
71: {
72: const BIGNUM *dsa_p_a, *dsa_q_a, *dsa_g_a, *dsa_pub_key_a;
73: const BIGNUM *dsa_p_b, *dsa_q_b, *dsa_g_b, *dsa_pub_key_b;
74:
75: if (a->dsa == NULL || b->dsa == NULL)
76: return 0;
77: DSA_get0_pqg(a->dsa, &dsa_p_a, &dsa_q_a, &dsa_g_a);
78: DSA_get0_pqg(b->dsa, &dsa_p_b, &dsa_q_b, &dsa_g_b);
79: DSA_get0_key(a->dsa, &dsa_pub_key_a, NULL);
80: DSA_get0_key(b->dsa, &dsa_pub_key_b, NULL);
81: if (dsa_p_a == NULL || dsa_p_b == NULL ||
82: dsa_q_a == NULL || dsa_q_b == NULL ||
83: dsa_g_a == NULL || dsa_g_b == NULL ||
84: dsa_pub_key_a == NULL || dsa_pub_key_b == NULL)
85: return 0;
86: if (BN_cmp(dsa_p_a, dsa_p_b) != 0)
87: return 0;
88: if (BN_cmp(dsa_q_a, dsa_q_b) != 0)
89: return 0;
90: if (BN_cmp(dsa_g_a, dsa_g_b) != 0)
91: return 0;
92: if (BN_cmp(dsa_pub_key_a, dsa_pub_key_b) != 0)
93: return 0;
94: return 1;
95: }
96:
1.42 djm 97: static int
98: ssh_dss_serialize_public(const struct sshkey *key, struct sshbuf *b,
99: const char *typename, enum sshkey_serialize_rep opts)
100: {
101: int r;
102: const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
103:
104: if (key->dsa == NULL)
105: return SSH_ERR_INVALID_ARGUMENT;
106: DSA_get0_pqg(key->dsa, &dsa_p, &dsa_q, &dsa_g);
107: DSA_get0_key(key->dsa, &dsa_pub_key, NULL);
108: if (dsa_p == NULL || dsa_q == NULL ||
109: dsa_g == NULL || dsa_pub_key == NULL)
110: return SSH_ERR_INTERNAL_ERROR;
111: if ((r = sshbuf_put_cstring(b, typename)) != 0 ||
112: (r = sshbuf_put_bignum2(b, dsa_p)) != 0 ||
113: (r = sshbuf_put_bignum2(b, dsa_q)) != 0 ||
114: (r = sshbuf_put_bignum2(b, dsa_g)) != 0 ||
115: (r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0)
116: return r;
117:
118: return 0;
119: }
120:
1.43 djm 121: static int
122: ssh_dss_generate(struct sshkey *k, int bits)
123: {
124: DSA *private;
125:
126: if (bits != 1024)
127: return SSH_ERR_KEY_LENGTH;
128: if ((private = DSA_new()) == NULL)
129: return SSH_ERR_ALLOC_FAIL;
130: if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL,
131: NULL, NULL) || !DSA_generate_key(private)) {
132: DSA_free(private);
133: return SSH_ERR_LIBCRYPTO_ERROR;
134: }
135: k->dsa = private;
136: return 0;
137: }
138:
1.44 ! djm 139: static int
! 140: ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to)
! 141: {
! 142: const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
! 143: BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
! 144: BIGNUM *dsa_pub_key_dup = NULL;
! 145: int r = SSH_ERR_INTERNAL_ERROR;
! 146:
! 147: DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g);
! 148: DSA_get0_key(from->dsa, &dsa_pub_key, NULL);
! 149: if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
! 150: (dsa_q_dup = BN_dup(dsa_q)) == NULL ||
! 151: (dsa_g_dup = BN_dup(dsa_g)) == NULL ||
! 152: (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
! 153: r = SSH_ERR_ALLOC_FAIL;
! 154: goto out;
! 155: }
! 156: if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
! 157: r = SSH_ERR_LIBCRYPTO_ERROR;
! 158: goto out;
! 159: }
! 160: dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
! 161: if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) {
! 162: r = SSH_ERR_LIBCRYPTO_ERROR;
! 163: goto out;
! 164: }
! 165: dsa_pub_key_dup = NULL; /* transferred */
! 166: /* success */
! 167: r = 0;
! 168: out:
! 169: BN_clear_free(dsa_p_dup);
! 170: BN_clear_free(dsa_q_dup);
! 171: BN_clear_free(dsa_g_dup);
! 172: BN_clear_free(dsa_pub_key_dup);
! 173: return r;
! 174: }
! 175:
1.1 markus 176: int
1.32 djm 177: ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
178: const u_char *data, size_t datalen, u_int compat)
1.1 markus 179: {
1.32 djm 180: DSA_SIG *sig = NULL;
1.38 djm 181: const BIGNUM *sig_r, *sig_s;
1.30 djm 182: u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
1.32 djm 183: size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
184: struct sshbuf *b = NULL;
185: int ret = SSH_ERR_INVALID_ARGUMENT;
186:
187: if (lenp != NULL)
188: *lenp = 0;
189: if (sigp != NULL)
190: *sigp = NULL;
191:
192: if (key == NULL || key->dsa == NULL ||
193: sshkey_type_plain(key->type) != KEY_DSA)
194: return SSH_ERR_INVALID_ARGUMENT;
195: if (dlen == 0)
196: return SSH_ERR_INTERNAL_ERROR;
197:
198: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
199: digest, sizeof(digest))) != 0)
200: goto out;
201:
202: if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
203: ret = SSH_ERR_LIBCRYPTO_ERROR;
204: goto out;
1.1 markus 205: }
206:
1.38 djm 207: DSA_SIG_get0(sig, &sig_r, &sig_s);
208: rlen = BN_num_bytes(sig_r);
209: slen = BN_num_bytes(sig_s);
1.1 markus 210: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.32 djm 211: ret = SSH_ERR_INTERNAL_ERROR;
212: goto out;
1.1 markus 213: }
1.31 djm 214: explicit_bzero(sigblob, SIGBLOB_LEN);
1.38 djm 215: BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
216: BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
1.1 markus 217:
1.36 djm 218: if ((b = sshbuf_new()) == NULL) {
219: ret = SSH_ERR_ALLOC_FAIL;
220: goto out;
221: }
222: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
223: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
224: goto out;
225:
226: len = sshbuf_len(b);
227: if (sigp != NULL) {
228: if ((*sigp = malloc(len)) == NULL) {
1.32 djm 229: ret = SSH_ERR_ALLOC_FAIL;
230: goto out;
231: }
1.36 djm 232: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 markus 233: }
1.36 djm 234: if (lenp != NULL)
235: *lenp = len;
236: ret = 0;
1.32 djm 237: out:
238: explicit_bzero(digest, sizeof(digest));
1.37 jsing 239: DSA_SIG_free(sig);
1.34 mmcc 240: sshbuf_free(b);
1.32 djm 241: return ret;
1.1 markus 242: }
1.32 djm 243:
1.1 markus 244: int
1.32 djm 245: ssh_dss_verify(const struct sshkey *key,
246: const u_char *signature, size_t signaturelen,
247: const u_char *data, size_t datalen, u_int compat)
1.1 markus 248: {
1.32 djm 249: DSA_SIG *sig = NULL;
1.38 djm 250: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.32 djm 251: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
252: size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
253: int ret = SSH_ERR_INTERNAL_ERROR;
254: struct sshbuf *b = NULL;
255: char *ktype = NULL;
256:
257: if (key == NULL || key->dsa == NULL ||
1.35 djm 258: sshkey_type_plain(key->type) != KEY_DSA ||
259: signature == NULL || signaturelen == 0)
1.32 djm 260: return SSH_ERR_INVALID_ARGUMENT;
261: if (dlen == 0)
262: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 263:
264: /* fetch signature */
1.36 djm 265: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
266: return SSH_ERR_ALLOC_FAIL;
267: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
268: sshbuf_get_string(b, &sigblob, &len) != 0) {
269: ret = SSH_ERR_INVALID_FORMAT;
270: goto out;
271: }
272: if (strcmp("ssh-dss", ktype) != 0) {
273: ret = SSH_ERR_KEY_TYPE_MISMATCH;
274: goto out;
275: }
276: if (sshbuf_len(b) != 0) {
277: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
278: goto out;
1.1 markus 279: }
280:
281: if (len != SIGBLOB_LEN) {
1.32 djm 282: ret = SSH_ERR_INVALID_FORMAT;
283: goto out;
1.1 markus 284: }
285:
286: /* parse signature */
1.32 djm 287: if ((sig = DSA_SIG_new()) == NULL ||
1.38 djm 288: (sig_r = BN_new()) == NULL ||
289: (sig_s = BN_new()) == NULL) {
1.32 djm 290: ret = SSH_ERR_ALLOC_FAIL;
291: goto out;
292: }
1.38 djm 293: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
294: (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
1.32 djm 295: ret = SSH_ERR_LIBCRYPTO_ERROR;
296: goto out;
297: }
1.38 djm 298: if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
299: ret = SSH_ERR_LIBCRYPTO_ERROR;
300: goto out;
301: }
302: sig_r = sig_s = NULL; /* transferred */
1.5 stevesk 303:
1.1 markus 304: /* sha1 the data */
1.32 djm 305: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
306: digest, sizeof(digest))) != 0)
307: goto out;
308:
309: switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
310: case 1:
311: ret = 0;
312: break;
313: case 0:
314: ret = SSH_ERR_SIGNATURE_INVALID;
315: goto out;
316: default:
317: ret = SSH_ERR_LIBCRYPTO_ERROR;
318: goto out;
1.30 djm 319: }
1.1 markus 320:
1.32 djm 321: out:
1.31 djm 322: explicit_bzero(digest, sizeof(digest));
1.37 jsing 323: DSA_SIG_free(sig);
1.38 djm 324: BN_clear_free(sig_r);
325: BN_clear_free(sig_s);
1.34 mmcc 326: sshbuf_free(b);
1.33 mmcc 327: free(ktype);
1.39 jsg 328: if (sigblob != NULL)
329: freezero(sigblob, len);
1.1 markus 330: return ret;
331: }
1.40 djm 332:
333: static const struct sshkey_impl_funcs sshkey_dss_funcs = {
334: /* .size = */ ssh_dss_size,
335: /* .alloc = */ ssh_dss_alloc,
336: /* .cleanup = */ ssh_dss_cleanup,
1.41 djm 337: /* .equal = */ ssh_dss_equal,
1.42 djm 338: /* .ssh_serialize_public = */ ssh_dss_serialize_public,
1.43 djm 339: /* .generate = */ ssh_dss_generate,
1.44 ! djm 340: /* .copy_public = */ ssh_dss_copy_public,
1.40 djm 341: };
342:
343: const struct sshkey_impl sshkey_dss_impl = {
344: /* .name = */ "ssh-dss",
345: /* .shortname = */ "DSA",
346: /* .sigalg = */ NULL,
347: /* .type = */ KEY_DSA,
348: /* .nid = */ 0,
349: /* .cert = */ 0,
350: /* .sigonly = */ 0,
351: /* .keybits = */ 0,
352: /* .funcs = */ &sshkey_dss_funcs,
353: };
354:
355: const struct sshkey_impl sshkey_dsa_cert_impl = {
356: /* .name = */ "ssh-dss-cert-v01@openssh.com",
357: /* .shortname = */ "DSA-CERT",
358: /* .sigalg = */ NULL,
359: /* .type = */ KEY_DSA_CERT,
360: /* .nid = */ 0,
361: /* .cert = */ 1,
362: /* .sigonly = */ 0,
363: /* .keybits = */ 0,
364: /* .funcs = */ &sshkey_dss_funcs,
365: };
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