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 1.5 2001/02/04 15:32:25 stevesk Exp $");
28 #include <openssl/bn.h>
29 #include <openssl/evp.h>
38 #define INTBLOB_LEN 20
39 #define SIGBLOB_LEN (2*INTBLOB_LEN)
44 u_char **sigp, int *lenp,
45 u_char *data, int datalen)
50 EVP_MD *evp_md = EVP_sha1();
55 u_char sigblob[SIGBLOB_LEN];
58 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
59 error("ssh_dss_sign: no DSA key");
62 dlen = evp_md->md_size;
63 digest = xmalloc(dlen);
64 EVP_DigestInit(&md, evp_md);
65 EVP_DigestUpdate(&md, data, datalen);
66 EVP_DigestFinal(&md, digest, NULL);
68 sig = DSA_do_sign(digest, dlen, key->dsa);
70 fatal("ssh_dss_sign: cannot sign");
72 memset(digest, 0, dlen);
75 rlen = BN_num_bytes(sig->r);
76 slen = BN_num_bytes(sig->s);
77 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
78 error("bad sig size %d %d", rlen, slen);
82 debug("sig size %d %d", rlen, slen);
84 memset(sigblob, 0, SIGBLOB_LEN);
85 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
86 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
89 if (datafellows & SSH_BUG_SIGBLOB) {
91 ret = xmalloc(SIGBLOB_LEN);
92 memcpy(ret, sigblob, SIGBLOB_LEN);
100 buffer_put_cstring(&b, "ssh-dss");
101 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
102 len = buffer_len(&b);
104 memcpy(ret, buffer_ptr(&b), len);
116 u_char *signature, int signaturelen,
117 u_char *data, int datalen)
122 EVP_MD *evp_md = EVP_sha1();
130 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
131 error("ssh_dss_verify: no DSA key");
135 if (!(datafellows & SSH_BUG_SIGBLOB) &&
136 signaturelen == SIGBLOB_LEN) {
137 datafellows |= ~SSH_BUG_SIGBLOB;
138 log("autodetect SSH_BUG_SIGBLOB");
139 } else if ((datafellows & SSH_BUG_SIGBLOB) &&
140 signaturelen != SIGBLOB_LEN) {
141 log("autoremove SSH_BUG_SIGBLOB");
142 datafellows &= ~SSH_BUG_SIGBLOB;
145 debug("len %d datafellows %d", signaturelen, datafellows);
147 /* fetch signature */
148 if (datafellows & SSH_BUG_SIGBLOB) {
155 buffer_append(&b, (char *) signature, signaturelen);
156 ktype = buffer_get_string(&b, NULL);
157 if (strcmp("ssh-dss", ktype) != 0) {
158 error("ssh_dss_verify: cannot handle type %s", ktype);
162 sigblob = (u_char *)buffer_get_string(&b, &len);
163 rlen = buffer_len(&b);
165 error("remaining bytes in signature %d", rlen);
173 if (len != SIGBLOB_LEN) {
174 fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
177 /* parse signature */
181 BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
182 BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
184 if (!(datafellows & SSH_BUG_SIGBLOB)) {
185 memset(sigblob, 0, len);
190 dlen = evp_md->md_size;
191 digest = xmalloc(dlen);
192 EVP_DigestInit(&md, evp_md);
193 EVP_DigestUpdate(&md, data, datalen);
194 EVP_DigestFinal(&md, digest, NULL);
196 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
198 memset(digest, 0, dlen);
214 debug("ssh_dss_verify: signature %s", txt);