Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.45
1.45 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.44 2022/10/28 00:41:17 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,
1.45 ! djm 99: enum sshkey_serialize_rep opts)
1.42 djm 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;
1.45 ! djm 111: if ((r = sshbuf_put_bignum2(b, dsa_p)) != 0 ||
1.42 djm 112: (r = sshbuf_put_bignum2(b, dsa_q)) != 0 ||
113: (r = sshbuf_put_bignum2(b, dsa_g)) != 0 ||
114: (r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0)
115: return r;
116:
117: return 0;
118: }
119:
1.43 djm 120: static int
121: ssh_dss_generate(struct sshkey *k, int bits)
122: {
123: DSA *private;
124:
125: if (bits != 1024)
126: return SSH_ERR_KEY_LENGTH;
127: if ((private = DSA_new()) == NULL)
128: return SSH_ERR_ALLOC_FAIL;
129: if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL,
130: NULL, NULL) || !DSA_generate_key(private)) {
131: DSA_free(private);
132: return SSH_ERR_LIBCRYPTO_ERROR;
133: }
134: k->dsa = private;
135: return 0;
136: }
137:
1.44 djm 138: static int
139: ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to)
140: {
141: const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
142: BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
143: BIGNUM *dsa_pub_key_dup = NULL;
144: int r = SSH_ERR_INTERNAL_ERROR;
145:
146: DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g);
147: DSA_get0_key(from->dsa, &dsa_pub_key, NULL);
148: if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
149: (dsa_q_dup = BN_dup(dsa_q)) == NULL ||
150: (dsa_g_dup = BN_dup(dsa_g)) == NULL ||
151: (dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
152: r = SSH_ERR_ALLOC_FAIL;
153: goto out;
154: }
155: if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
156: r = SSH_ERR_LIBCRYPTO_ERROR;
157: goto out;
158: }
159: dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
160: if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) {
161: r = SSH_ERR_LIBCRYPTO_ERROR;
162: goto out;
163: }
164: dsa_pub_key_dup = NULL; /* transferred */
165: /* success */
166: r = 0;
167: out:
168: BN_clear_free(dsa_p_dup);
169: BN_clear_free(dsa_q_dup);
170: BN_clear_free(dsa_g_dup);
171: BN_clear_free(dsa_pub_key_dup);
172: return r;
173: }
174:
1.45 ! djm 175: static int
! 176: ssh_dss_deserialize_public(const char *ktype, struct sshbuf *b,
! 177: struct sshkey *key)
! 178: {
! 179: int ret = SSH_ERR_INTERNAL_ERROR;
! 180: BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL, *dsa_pub_key = NULL;
! 181:
! 182: if (sshbuf_get_bignum2(b, &dsa_p) != 0 ||
! 183: sshbuf_get_bignum2(b, &dsa_q) != 0 ||
! 184: sshbuf_get_bignum2(b, &dsa_g) != 0 ||
! 185: sshbuf_get_bignum2(b, &dsa_pub_key) != 0) {
! 186: ret = SSH_ERR_INVALID_FORMAT;
! 187: goto out;
! 188: }
! 189: if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g)) {
! 190: ret = SSH_ERR_LIBCRYPTO_ERROR;
! 191: goto out;
! 192: }
! 193: dsa_p = dsa_q = dsa_g = NULL; /* transferred */
! 194: if (!DSA_set0_key(key->dsa, dsa_pub_key, NULL)) {
! 195: ret = SSH_ERR_LIBCRYPTO_ERROR;
! 196: goto out;
! 197: }
! 198: dsa_pub_key = NULL; /* transferred */
! 199: #ifdef DEBUG_PK
! 200: DSA_print_fp(stderr, key->dsa, 8);
! 201: #endif
! 202: /* success */
! 203: ret = 0;
! 204: out:
! 205: BN_clear_free(dsa_p);
! 206: BN_clear_free(dsa_q);
! 207: BN_clear_free(dsa_g);
! 208: BN_clear_free(dsa_pub_key);
! 209: return ret;
! 210: }
! 211:
1.1 markus 212: int
1.32 djm 213: ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
214: const u_char *data, size_t datalen, u_int compat)
1.1 markus 215: {
1.32 djm 216: DSA_SIG *sig = NULL;
1.38 djm 217: const BIGNUM *sig_r, *sig_s;
1.30 djm 218: u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
1.32 djm 219: size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
220: struct sshbuf *b = NULL;
221: int ret = SSH_ERR_INVALID_ARGUMENT;
222:
223: if (lenp != NULL)
224: *lenp = 0;
225: if (sigp != NULL)
226: *sigp = NULL;
227:
228: if (key == NULL || key->dsa == NULL ||
229: sshkey_type_plain(key->type) != KEY_DSA)
230: return SSH_ERR_INVALID_ARGUMENT;
231: if (dlen == 0)
232: return SSH_ERR_INTERNAL_ERROR;
233:
234: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
235: digest, sizeof(digest))) != 0)
236: goto out;
237:
238: if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
239: ret = SSH_ERR_LIBCRYPTO_ERROR;
240: goto out;
1.1 markus 241: }
242:
1.38 djm 243: DSA_SIG_get0(sig, &sig_r, &sig_s);
244: rlen = BN_num_bytes(sig_r);
245: slen = BN_num_bytes(sig_s);
1.1 markus 246: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.32 djm 247: ret = SSH_ERR_INTERNAL_ERROR;
248: goto out;
1.1 markus 249: }
1.31 djm 250: explicit_bzero(sigblob, SIGBLOB_LEN);
1.38 djm 251: BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
252: BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
1.1 markus 253:
1.36 djm 254: if ((b = sshbuf_new()) == NULL) {
255: ret = SSH_ERR_ALLOC_FAIL;
256: goto out;
257: }
258: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
259: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
260: goto out;
261:
262: len = sshbuf_len(b);
263: if (sigp != NULL) {
264: if ((*sigp = malloc(len)) == NULL) {
1.32 djm 265: ret = SSH_ERR_ALLOC_FAIL;
266: goto out;
267: }
1.36 djm 268: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 markus 269: }
1.36 djm 270: if (lenp != NULL)
271: *lenp = len;
272: ret = 0;
1.32 djm 273: out:
274: explicit_bzero(digest, sizeof(digest));
1.37 jsing 275: DSA_SIG_free(sig);
1.34 mmcc 276: sshbuf_free(b);
1.32 djm 277: return ret;
1.1 markus 278: }
1.32 djm 279:
1.1 markus 280: int
1.32 djm 281: ssh_dss_verify(const struct sshkey *key,
282: const u_char *signature, size_t signaturelen,
283: const u_char *data, size_t datalen, u_int compat)
1.1 markus 284: {
1.32 djm 285: DSA_SIG *sig = NULL;
1.38 djm 286: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.32 djm 287: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
288: size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
289: int ret = SSH_ERR_INTERNAL_ERROR;
290: struct sshbuf *b = NULL;
291: char *ktype = NULL;
292:
293: if (key == NULL || key->dsa == NULL ||
1.35 djm 294: sshkey_type_plain(key->type) != KEY_DSA ||
295: signature == NULL || signaturelen == 0)
1.32 djm 296: return SSH_ERR_INVALID_ARGUMENT;
297: if (dlen == 0)
298: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 299:
300: /* fetch signature */
1.36 djm 301: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
302: return SSH_ERR_ALLOC_FAIL;
303: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
304: sshbuf_get_string(b, &sigblob, &len) != 0) {
305: ret = SSH_ERR_INVALID_FORMAT;
306: goto out;
307: }
308: if (strcmp("ssh-dss", ktype) != 0) {
309: ret = SSH_ERR_KEY_TYPE_MISMATCH;
310: goto out;
311: }
312: if (sshbuf_len(b) != 0) {
313: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
314: goto out;
1.1 markus 315: }
316:
317: if (len != SIGBLOB_LEN) {
1.32 djm 318: ret = SSH_ERR_INVALID_FORMAT;
319: goto out;
1.1 markus 320: }
321:
322: /* parse signature */
1.32 djm 323: if ((sig = DSA_SIG_new()) == NULL ||
1.38 djm 324: (sig_r = BN_new()) == NULL ||
325: (sig_s = BN_new()) == NULL) {
1.32 djm 326: ret = SSH_ERR_ALLOC_FAIL;
327: goto out;
328: }
1.38 djm 329: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
330: (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
1.32 djm 331: ret = SSH_ERR_LIBCRYPTO_ERROR;
332: goto out;
333: }
1.38 djm 334: if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
335: ret = SSH_ERR_LIBCRYPTO_ERROR;
336: goto out;
337: }
338: sig_r = sig_s = NULL; /* transferred */
1.5 stevesk 339:
1.1 markus 340: /* sha1 the data */
1.32 djm 341: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
342: digest, sizeof(digest))) != 0)
343: goto out;
344:
345: switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
346: case 1:
347: ret = 0;
348: break;
349: case 0:
350: ret = SSH_ERR_SIGNATURE_INVALID;
351: goto out;
352: default:
353: ret = SSH_ERR_LIBCRYPTO_ERROR;
354: goto out;
1.30 djm 355: }
1.1 markus 356:
1.32 djm 357: out:
1.31 djm 358: explicit_bzero(digest, sizeof(digest));
1.37 jsing 359: DSA_SIG_free(sig);
1.38 djm 360: BN_clear_free(sig_r);
361: BN_clear_free(sig_s);
1.34 mmcc 362: sshbuf_free(b);
1.33 mmcc 363: free(ktype);
1.39 jsg 364: if (sigblob != NULL)
365: freezero(sigblob, len);
1.1 markus 366: return ret;
367: }
1.40 djm 368:
369: static const struct sshkey_impl_funcs sshkey_dss_funcs = {
370: /* .size = */ ssh_dss_size,
371: /* .alloc = */ ssh_dss_alloc,
372: /* .cleanup = */ ssh_dss_cleanup,
1.41 djm 373: /* .equal = */ ssh_dss_equal,
1.42 djm 374: /* .ssh_serialize_public = */ ssh_dss_serialize_public,
1.45 ! djm 375: /* .ssh_deserialize_public = */ ssh_dss_deserialize_public,
1.43 djm 376: /* .generate = */ ssh_dss_generate,
1.44 djm 377: /* .copy_public = */ ssh_dss_copy_public,
1.40 djm 378: };
379:
380: const struct sshkey_impl sshkey_dss_impl = {
381: /* .name = */ "ssh-dss",
382: /* .shortname = */ "DSA",
383: /* .sigalg = */ NULL,
384: /* .type = */ KEY_DSA,
385: /* .nid = */ 0,
386: /* .cert = */ 0,
387: /* .sigonly = */ 0,
388: /* .keybits = */ 0,
389: /* .funcs = */ &sshkey_dss_funcs,
390: };
391:
392: const struct sshkey_impl sshkey_dsa_cert_impl = {
393: /* .name = */ "ssh-dss-cert-v01@openssh.com",
394: /* .shortname = */ "DSA-CERT",
395: /* .sigalg = */ NULL,
396: /* .type = */ KEY_DSA_CERT,
397: /* .nid = */ 0,
398: /* .cert = */ 1,
399: /* .sigonly = */ 0,
400: /* .keybits = */ 0,
401: /* .funcs = */ &sshkey_dss_funcs,
402: };
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