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 1.19 2003/11/10 16:23:41 jakob Exp $");
28 #include <openssl/bn.h>
29 #include <openssl/evp.h>
38 #define INTBLOB_LEN 20
39 #define SIGBLOB_LEN (2*INTBLOB_LEN)
42 ssh_dss_sign(const Key *key, u_char **sigp, u_int *lenp,
43 const u_char *data, u_int datalen)
46 const EVP_MD *evp_md = EVP_sha1();
48 u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
49 u_int rlen, slen, len, dlen;
52 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
53 error("ssh_dss_sign: no DSA key");
56 EVP_DigestInit(&md, evp_md);
57 EVP_DigestUpdate(&md, data, datalen);
58 EVP_DigestFinal(&md, digest, &dlen);
60 sig = DSA_do_sign(digest, dlen, key->dsa);
61 memset(digest, 'd', sizeof(digest));
64 error("ssh_dss_sign: sign failed");
68 rlen = BN_num_bytes(sig->r);
69 slen = BN_num_bytes(sig->s);
70 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
71 error("bad sig size %u %u", rlen, slen);
75 memset(sigblob, 0, SIGBLOB_LEN);
76 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
77 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
80 if (datafellows & SSH_BUG_SIGBLOB) {
84 *sigp = xmalloc(SIGBLOB_LEN);
85 memcpy(*sigp, sigblob, SIGBLOB_LEN);
90 buffer_put_cstring(&b, "ssh-dss");
91 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
97 memcpy(*sigp, buffer_ptr(&b), len);
104 ssh_dss_verify(const Key *key, const u_char *signature, u_int signaturelen,
105 const u_char *data, u_int datalen)
108 const EVP_MD *evp_md = EVP_sha1();
110 u_char digest[EVP_MAX_MD_SIZE], *sigblob;
115 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
116 error("ssh_dss_verify: no DSA key");
120 /* fetch signature */
121 if (datafellows & SSH_BUG_SIGBLOB) {
122 sigblob = xmalloc(signaturelen);
123 memcpy(sigblob, signature, signaturelen);
129 buffer_append(&b, signature, signaturelen);
130 ktype = buffer_get_string(&b, NULL);
131 if (strcmp("ssh-dss", ktype) != 0) {
132 error("ssh_dss_verify: cannot handle type %s", ktype);
138 sigblob = buffer_get_string(&b, &len);
139 rlen = buffer_len(&b);
142 error("ssh_dss_verify: "
143 "remaining bytes in signature %d", rlen);
149 if (len != SIGBLOB_LEN) {
150 fatal("bad sigbloblen %u != SIGBLOB_LEN", len);
153 /* parse signature */
154 if ((sig = DSA_SIG_new()) == NULL)
155 fatal("ssh_dss_verify: DSA_SIG_new failed");
156 if ((sig->r = BN_new()) == NULL)
157 fatal("ssh_dss_verify: BN_new failed");
158 if ((sig->s = BN_new()) == NULL)
159 fatal("ssh_dss_verify: BN_new failed");
160 BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
161 BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
164 memset(sigblob, 0, len);
168 EVP_DigestInit(&md, evp_md);
169 EVP_DigestUpdate(&md, data, datalen);
170 EVP_DigestFinal(&md, digest, &dlen);
172 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
173 memset(digest, 'd', sizeof(digest));
177 debug("ssh_dss_verify: signature %s",
178 ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");