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 1.6 2001/02/08 19:30:52 itojun 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)
51 EVP_MD *evp_md = EVP_sha1();
56 u_char sigblob[SIGBLOB_LEN];
59 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
60 error("ssh_dss_sign: no DSA key");
63 dlen = evp_md->md_size;
64 digest = xmalloc(dlen);
65 EVP_DigestInit(&md, evp_md);
66 EVP_DigestUpdate(&md, data, datalen);
67 EVP_DigestFinal(&md, digest, NULL);
69 sig = DSA_do_sign(digest, dlen, key->dsa);
71 fatal("ssh_dss_sign: cannot sign");
73 memset(digest, 0, dlen);
76 rlen = BN_num_bytes(sig->r);
77 slen = BN_num_bytes(sig->s);
78 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
79 error("bad sig size %d %d", rlen, slen);
83 debug("sig size %d %d", rlen, slen);
85 memset(sigblob, 0, SIGBLOB_LEN);
86 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
87 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
90 if (datafellows & SSH_BUG_SIGBLOB) {
92 ret = xmalloc(SIGBLOB_LEN);
93 memcpy(ret, sigblob, SIGBLOB_LEN);
101 buffer_put_cstring(&b, "ssh-dss");
102 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
103 len = buffer_len(&b);
105 memcpy(ret, buffer_ptr(&b), len);
117 u_char *signature, int signaturelen,
118 u_char *data, int datalen)
123 EVP_MD *evp_md = EVP_sha1();
131 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
132 error("ssh_dss_verify: no DSA key");
136 if (!(datafellows & SSH_BUG_SIGBLOB) &&
137 signaturelen == SIGBLOB_LEN) {
138 datafellows |= ~SSH_BUG_SIGBLOB;
139 log("autodetect SSH_BUG_SIGBLOB");
140 } else if ((datafellows & SSH_BUG_SIGBLOB) &&
141 signaturelen != SIGBLOB_LEN) {
142 log("autoremove SSH_BUG_SIGBLOB");
143 datafellows &= ~SSH_BUG_SIGBLOB;
146 debug("len %d datafellows %d", signaturelen, datafellows);
148 /* fetch signature */
149 if (datafellows & SSH_BUG_SIGBLOB) {
156 buffer_append(&b, (char *) signature, signaturelen);
157 ktype = buffer_get_string(&b, NULL);
158 if (strcmp("ssh-dss", ktype) != 0) {
159 error("ssh_dss_verify: cannot handle type %s", ktype);
163 sigblob = (u_char *)buffer_get_string(&b, &len);
164 rlen = buffer_len(&b);
166 error("remaining bytes in signature %d", rlen);
174 if (len != SIGBLOB_LEN) {
175 fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
178 /* parse signature */
182 BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
183 BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
185 if (!(datafellows & SSH_BUG_SIGBLOB)) {
186 memset(sigblob, 0, len);
191 dlen = evp_md->md_size;
192 digest = xmalloc(dlen);
193 EVP_DigestInit(&md, evp_md);
194 EVP_DigestUpdate(&md, data, datalen);
195 EVP_DigestFinal(&md, digest, NULL);
197 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
199 memset(digest, 0, dlen);
215 debug("ssh_dss_verify: signature %s", txt);