Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.43
1.43 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.42 2022/10/28 00:37:24 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:
1.1 markus 139: int
1.32 djm 140: ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
141: const u_char *data, size_t datalen, u_int compat)
1.1 markus 142: {
1.32 djm 143: DSA_SIG *sig = NULL;
1.38 djm 144: const BIGNUM *sig_r, *sig_s;
1.30 djm 145: u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
1.32 djm 146: size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
147: struct sshbuf *b = NULL;
148: int ret = SSH_ERR_INVALID_ARGUMENT;
149:
150: if (lenp != NULL)
151: *lenp = 0;
152: if (sigp != NULL)
153: *sigp = NULL;
154:
155: if (key == NULL || key->dsa == NULL ||
156: sshkey_type_plain(key->type) != KEY_DSA)
157: return SSH_ERR_INVALID_ARGUMENT;
158: if (dlen == 0)
159: return SSH_ERR_INTERNAL_ERROR;
160:
161: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
162: digest, sizeof(digest))) != 0)
163: goto out;
164:
165: if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
166: ret = SSH_ERR_LIBCRYPTO_ERROR;
167: goto out;
1.1 markus 168: }
169:
1.38 djm 170: DSA_SIG_get0(sig, &sig_r, &sig_s);
171: rlen = BN_num_bytes(sig_r);
172: slen = BN_num_bytes(sig_s);
1.1 markus 173: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.32 djm 174: ret = SSH_ERR_INTERNAL_ERROR;
175: goto out;
1.1 markus 176: }
1.31 djm 177: explicit_bzero(sigblob, SIGBLOB_LEN);
1.38 djm 178: BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
179: BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
1.1 markus 180:
1.36 djm 181: if ((b = sshbuf_new()) == NULL) {
182: ret = SSH_ERR_ALLOC_FAIL;
183: goto out;
184: }
185: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
186: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
187: goto out;
188:
189: len = sshbuf_len(b);
190: if (sigp != NULL) {
191: if ((*sigp = malloc(len)) == NULL) {
1.32 djm 192: ret = SSH_ERR_ALLOC_FAIL;
193: goto out;
194: }
1.36 djm 195: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 markus 196: }
1.36 djm 197: if (lenp != NULL)
198: *lenp = len;
199: ret = 0;
1.32 djm 200: out:
201: explicit_bzero(digest, sizeof(digest));
1.37 jsing 202: DSA_SIG_free(sig);
1.34 mmcc 203: sshbuf_free(b);
1.32 djm 204: return ret;
1.1 markus 205: }
1.32 djm 206:
1.1 markus 207: int
1.32 djm 208: ssh_dss_verify(const struct sshkey *key,
209: const u_char *signature, size_t signaturelen,
210: const u_char *data, size_t datalen, u_int compat)
1.1 markus 211: {
1.32 djm 212: DSA_SIG *sig = NULL;
1.38 djm 213: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.32 djm 214: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
215: size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
216: int ret = SSH_ERR_INTERNAL_ERROR;
217: struct sshbuf *b = NULL;
218: char *ktype = NULL;
219:
220: if (key == NULL || key->dsa == NULL ||
1.35 djm 221: sshkey_type_plain(key->type) != KEY_DSA ||
222: signature == NULL || signaturelen == 0)
1.32 djm 223: return SSH_ERR_INVALID_ARGUMENT;
224: if (dlen == 0)
225: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 226:
227: /* fetch signature */
1.36 djm 228: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
229: return SSH_ERR_ALLOC_FAIL;
230: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
231: sshbuf_get_string(b, &sigblob, &len) != 0) {
232: ret = SSH_ERR_INVALID_FORMAT;
233: goto out;
234: }
235: if (strcmp("ssh-dss", ktype) != 0) {
236: ret = SSH_ERR_KEY_TYPE_MISMATCH;
237: goto out;
238: }
239: if (sshbuf_len(b) != 0) {
240: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
241: goto out;
1.1 markus 242: }
243:
244: if (len != SIGBLOB_LEN) {
1.32 djm 245: ret = SSH_ERR_INVALID_FORMAT;
246: goto out;
1.1 markus 247: }
248:
249: /* parse signature */
1.32 djm 250: if ((sig = DSA_SIG_new()) == NULL ||
1.38 djm 251: (sig_r = BN_new()) == NULL ||
252: (sig_s = BN_new()) == NULL) {
1.32 djm 253: ret = SSH_ERR_ALLOC_FAIL;
254: goto out;
255: }
1.38 djm 256: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
257: (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
1.32 djm 258: ret = SSH_ERR_LIBCRYPTO_ERROR;
259: goto out;
260: }
1.38 djm 261: if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
262: ret = SSH_ERR_LIBCRYPTO_ERROR;
263: goto out;
264: }
265: sig_r = sig_s = NULL; /* transferred */
1.5 stevesk 266:
1.1 markus 267: /* sha1 the data */
1.32 djm 268: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
269: digest, sizeof(digest))) != 0)
270: goto out;
271:
272: switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
273: case 1:
274: ret = 0;
275: break;
276: case 0:
277: ret = SSH_ERR_SIGNATURE_INVALID;
278: goto out;
279: default:
280: ret = SSH_ERR_LIBCRYPTO_ERROR;
281: goto out;
1.30 djm 282: }
1.1 markus 283:
1.32 djm 284: out:
1.31 djm 285: explicit_bzero(digest, sizeof(digest));
1.37 jsing 286: DSA_SIG_free(sig);
1.38 djm 287: BN_clear_free(sig_r);
288: BN_clear_free(sig_s);
1.34 mmcc 289: sshbuf_free(b);
1.33 mmcc 290: free(ktype);
1.39 jsg 291: if (sigblob != NULL)
292: freezero(sigblob, len);
1.1 markus 293: return ret;
294: }
1.40 djm 295:
296: static const struct sshkey_impl_funcs sshkey_dss_funcs = {
297: /* .size = */ ssh_dss_size,
298: /* .alloc = */ ssh_dss_alloc,
299: /* .cleanup = */ ssh_dss_cleanup,
1.41 djm 300: /* .equal = */ ssh_dss_equal,
1.42 djm 301: /* .ssh_serialize_public = */ ssh_dss_serialize_public,
1.43 ! djm 302: /* .generate = */ ssh_dss_generate,
1.40 djm 303: };
304:
305: const struct sshkey_impl sshkey_dss_impl = {
306: /* .name = */ "ssh-dss",
307: /* .shortname = */ "DSA",
308: /* .sigalg = */ NULL,
309: /* .type = */ KEY_DSA,
310: /* .nid = */ 0,
311: /* .cert = */ 0,
312: /* .sigonly = */ 0,
313: /* .keybits = */ 0,
314: /* .funcs = */ &sshkey_dss_funcs,
315: };
316:
317: const struct sshkey_impl sshkey_dsa_cert_impl = {
318: /* .name = */ "ssh-dss-cert-v01@openssh.com",
319: /* .shortname = */ "DSA-CERT",
320: /* .sigalg = */ NULL,
321: /* .type = */ KEY_DSA_CERT,
322: /* .nid = */ 0,
323: /* .cert = */ 1,
324: /* .sigonly = */ 0,
325: /* .keybits = */ 0,
326: /* .funcs = */ &sshkey_dss_funcs,
327: };
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