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 1.13 2002/02/24 19:14:59 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, u_int *lenp,
46 u_char *data, u_int datalen)
49 EVP_MD *evp_md = EVP_sha1();
51 u_char *ret, digest[EVP_MAX_MD_SIZE], 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 EVP_DigestInit(&md, evp_md);
60 EVP_DigestUpdate(&md, data, datalen);
61 EVP_DigestFinal(&md, digest, &dlen);
63 sig = DSA_do_sign(digest, dlen, key->dsa);
64 memset(digest, 'd', sizeof(digest));
67 error("ssh_dss_sign: sign failed");
71 rlen = BN_num_bytes(sig->r);
72 slen = BN_num_bytes(sig->s);
73 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
74 error("bad sig size %d %d", rlen, slen);
78 memset(sigblob, 0, SIGBLOB_LEN);
79 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
80 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
83 if (datafellows & SSH_BUG_SIGBLOB) {
84 ret = xmalloc(SIGBLOB_LEN);
85 memcpy(ret, sigblob, SIGBLOB_LEN);
93 buffer_put_cstring(&b, "ssh-dss");
94 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
97 memcpy(ret, buffer_ptr(&b), len);
109 u_char *signature, u_int signaturelen,
110 u_char *data, u_int datalen)
113 EVP_MD *evp_md = EVP_sha1();
115 u_char digest[EVP_MAX_MD_SIZE], *sigblob;
120 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
121 error("ssh_dss_verify: no DSA key");
125 /* fetch signature */
126 if (datafellows & SSH_BUG_SIGBLOB) {
133 buffer_append(&b, signature, signaturelen);
134 ktype = buffer_get_string(&b, NULL);
135 if (strcmp("ssh-dss", ktype) != 0) {
136 error("ssh_dss_verify: cannot handle type %s", ktype);
142 sigblob = buffer_get_string(&b, &len);
143 rlen = buffer_len(&b);
146 error("ssh_dss_verify: "
147 "remaining bytes in signature %d", rlen);
153 if (len != SIGBLOB_LEN) {
154 fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
157 /* parse signature */
158 if ((sig = DSA_SIG_new()) == NULL)
159 fatal("ssh_dss_verify: DSA_SIG_new failed");
160 if ((sig->r = BN_new()) == NULL)
161 fatal("ssh_dss_verify: BN_new failed");
162 if ((sig->s = BN_new()) == NULL)
163 fatal("ssh_dss_verify: BN_new failed");
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 EVP_DigestInit(&md, evp_md);
174 EVP_DigestUpdate(&md, data, datalen);
175 EVP_DigestFinal(&md, digest, &dlen);
177 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
178 memset(digest, 'd', sizeof(digest));
182 debug("ssh_dss_verify: signature %s",
183 ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");