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 1.17 2002/07/04 10:41:47 markus Exp $");
28 #include <openssl/bn.h>
29 #include <openssl/evp.h>
39 #define INTBLOB_LEN 20
40 #define SIGBLOB_LEN (2*INTBLOB_LEN)
43 ssh_dss_sign(Key *key, u_char **sigp, u_int *lenp,
44 u_char *data, u_int datalen)
47 const EVP_MD *evp_md = EVP_sha1();
49 u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
50 u_int rlen, slen, len, dlen;
53 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
54 error("ssh_dss_sign: no DSA key");
57 EVP_DigestInit(&md, evp_md);
58 EVP_DigestUpdate(&md, data, datalen);
59 EVP_DigestFinal(&md, digest, &dlen);
61 sig = DSA_do_sign(digest, dlen, key->dsa);
62 memset(digest, 'd', sizeof(digest));
65 error("ssh_dss_sign: sign failed");
69 rlen = BN_num_bytes(sig->r);
70 slen = BN_num_bytes(sig->s);
71 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
72 error("bad sig size %u %u", rlen, slen);
76 memset(sigblob, 0, SIGBLOB_LEN);
77 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
78 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
81 if (datafellows & SSH_BUG_SIGBLOB) {
85 *sigp = xmalloc(SIGBLOB_LEN);
86 memcpy(*sigp, sigblob, SIGBLOB_LEN);
91 buffer_put_cstring(&b, "ssh-dss");
92 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
98 memcpy(*sigp, buffer_ptr(&b), len);
105 ssh_dss_verify(Key *key, u_char *signature, u_int signaturelen,
106 u_char *data, u_int datalen)
109 const EVP_MD *evp_md = EVP_sha1();
111 u_char digest[EVP_MAX_MD_SIZE], *sigblob;
116 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
117 error("ssh_dss_verify: no DSA key");
121 /* fetch signature */
122 if (datafellows & SSH_BUG_SIGBLOB) {
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);
163 if (!(datafellows & SSH_BUG_SIGBLOB)) {
164 memset(sigblob, 0, len);
169 EVP_DigestInit(&md, evp_md);
170 EVP_DigestUpdate(&md, data, datalen);
171 EVP_DigestFinal(&md, digest, &dlen);
173 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
174 memset(digest, 'd', sizeof(digest));
178 debug("ssh_dss_verify: signature %s",
179 ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");