2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 RCSID("$OpenBSD: ssh-dss.c,v 1.9 2001/11/07 22:10:28 markus Exp $");
28 #include <openssl/bn.h>
29 #include <openssl/evp.h>
39 #define INTBLOB_LEN 20
40 #define SIGBLOB_LEN (2*INTBLOB_LEN)
45 u_char **sigp, int *lenp,
46 u_char *data, int datalen)
49 EVP_MD *evp_md = EVP_sha1();
51 u_char *digest, *ret, sigblob[SIGBLOB_LEN];
52 u_int rlen, slen, len, dlen;
55 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
56 error("ssh_dss_sign: no DSA key");
59 dlen = evp_md->md_size;
60 digest = xmalloc(dlen);
61 EVP_DigestInit(&md, evp_md);
62 EVP_DigestUpdate(&md, data, datalen);
63 EVP_DigestFinal(&md, digest, NULL);
65 sig = DSA_do_sign(digest, dlen, key->dsa);
67 memset(digest, 0, dlen);
70 error("ssh_dss_sign: sign failed");
74 rlen = BN_num_bytes(sig->r);
75 slen = BN_num_bytes(sig->s);
76 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
77 error("bad sig size %d %d", rlen, slen);
81 memset(sigblob, 0, SIGBLOB_LEN);
82 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
83 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
86 if (datafellows & SSH_BUG_SIGBLOB) {
87 ret = xmalloc(SIGBLOB_LEN);
88 memcpy(ret, sigblob, SIGBLOB_LEN);
96 buffer_put_cstring(&b, "ssh-dss");
97 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
100 memcpy(ret, buffer_ptr(&b), len);
112 u_char *signature, int signaturelen,
113 u_char *data, int datalen)
116 EVP_MD *evp_md = EVP_sha1();
118 u_char *digest, *sigblob;
123 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
124 error("ssh_dss_verify: no DSA key");
128 /* fetch signature */
129 if (datafellows & SSH_BUG_SIGBLOB) {
136 buffer_append(&b, signature, signaturelen);
137 ktype = buffer_get_string(&b, NULL);
138 if (strcmp("ssh-dss", ktype) != 0) {
139 error("ssh_dss_verify: cannot handle type %s", ktype);
145 sigblob = buffer_get_string(&b, &len);
146 rlen = buffer_len(&b);
149 error("ssh_dss_verify: "
150 "remaining bytes in signature %d", rlen);
156 if (len != SIGBLOB_LEN) {
157 fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
160 /* parse signature */
164 BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
165 BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
167 if (!(datafellows & SSH_BUG_SIGBLOB)) {
168 memset(sigblob, 0, len);
173 dlen = evp_md->md_size;
174 digest = xmalloc(dlen);
175 EVP_DigestInit(&md, evp_md);
176 EVP_DigestUpdate(&md, data, datalen);
177 EVP_DigestFinal(&md, digest, NULL);
179 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
181 memset(digest, 0, dlen);
185 debug("ssh_dss_verify: signature %s",
186 ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");