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.
27 #include <openssl/bn.h>
28 #include <openssl/evp.h>
37 #define INTBLOB_LEN 20
38 #define SIGBLOB_LEN (2*INTBLOB_LEN)
41 ssh_dss_sign(const Key *key, u_char **sigp, u_int *lenp,
42 const u_char *data, u_int datalen)
45 const EVP_MD *evp_md = EVP_sha1();
47 u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
48 u_int rlen, slen, len, dlen;
51 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
52 error("ssh_dss_sign: no DSA key");
55 EVP_DigestInit(&md, evp_md);
56 EVP_DigestUpdate(&md, data, datalen);
57 EVP_DigestFinal(&md, digest, &dlen);
59 sig = DSA_do_sign(digest, dlen, key->dsa);
60 memset(digest, 'd', sizeof(digest));
63 error("ssh_dss_sign: sign failed");
67 rlen = BN_num_bytes(sig->r);
68 slen = BN_num_bytes(sig->s);
69 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
70 error("bad sig size %u %u", rlen, slen);
74 memset(sigblob, 0, SIGBLOB_LEN);
75 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
76 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
79 if (datafellows & SSH_BUG_SIGBLOB) {
83 *sigp = xmalloc(SIGBLOB_LEN);
84 memcpy(*sigp, sigblob, SIGBLOB_LEN);
89 buffer_put_cstring(&b, "ssh-dss");
90 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
96 memcpy(*sigp, buffer_ptr(&b), len);
103 ssh_dss_verify(const Key *key, const u_char *signature, u_int signaturelen,
104 const u_char *data, u_int datalen)
107 const EVP_MD *evp_md = EVP_sha1();
109 u_char digest[EVP_MAX_MD_SIZE], *sigblob;
114 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
115 error("ssh_dss_verify: no DSA key");
119 /* fetch signature */
120 if (datafellows & SSH_BUG_SIGBLOB) {
121 sigblob = xmalloc(signaturelen);
122 memcpy(sigblob, signature, signaturelen);
128 buffer_append(&b, signature, signaturelen);
129 ktype = buffer_get_string(&b, NULL);
130 if (strcmp("ssh-dss", ktype) != 0) {
131 error("ssh_dss_verify: cannot handle type %s", ktype);
137 sigblob = buffer_get_string(&b, &len);
138 rlen = buffer_len(&b);
141 error("ssh_dss_verify: "
142 "remaining bytes in signature %d", rlen);
148 if (len != SIGBLOB_LEN) {
149 fatal("bad sigbloblen %u != SIGBLOB_LEN", len);
152 /* parse signature */
153 if ((sig = DSA_SIG_new()) == NULL)
154 fatal("ssh_dss_verify: DSA_SIG_new failed");
155 if ((sig->r = BN_new()) == NULL)
156 fatal("ssh_dss_verify: BN_new failed");
157 if ((sig->s = BN_new()) == NULL)
158 fatal("ssh_dss_verify: BN_new failed");
159 BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
160 BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
163 memset(sigblob, 0, len);
167 EVP_DigestInit(&md, evp_md);
168 EVP_DigestUpdate(&md, data, datalen);
169 EVP_DigestFinal(&md, digest, &dlen);
171 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
172 memset(digest, 'd', sizeof(digest));
176 debug("ssh_dss_verify: signature %s",
177 ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");