blob: 22fffa02afa1c8770991d32e25528a6903a241a7 [file] [log] [blame]
Damien Millera664e872000-04-16 11:52:47 +10001/*
2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
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.
Damien Millera664e872000-04-16 11:52:47 +100012 *
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.
23 */
24
25#include "includes.h"
Ben Lindstrom9e0ddd42001-09-18 05:41:19 +000026RCSID("$OpenBSD: ssh-dss.c,v 1.8 2001/09/17 19:27:15 stevesk Exp $");
Damien Millera664e872000-04-16 11:52:47 +100027
Ben Lindstrom226cfa02001-01-22 05:34:40 +000028#include <openssl/bn.h>
29#include <openssl/evp.h>
30
Damien Millera664e872000-04-16 11:52:47 +100031#include "xmalloc.h"
32#include "buffer.h"
33#include "bufaux.h"
34#include "compat.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000035#include "log.h"
Damien Millera664e872000-04-16 11:52:47 +100036#include "key.h"
Ben Lindstrom31ca54a2001-02-09 02:11:24 +000037#include "ssh-dss.h"
Damien Millera664e872000-04-16 11:52:47 +100038
39#define INTBLOB_LEN 20
40#define SIGBLOB_LEN (2*INTBLOB_LEN)
41
Damien Millera664e872000-04-16 11:52:47 +100042int
Damien Miller0bc1bd82000-11-13 22:57:25 +110043ssh_dss_sign(
Damien Millera664e872000-04-16 11:52:47 +100044 Key *key,
Ben Lindstrom46c16222000-12-22 01:43:59 +000045 u_char **sigp, int *lenp,
46 u_char *data, int datalen)
Damien Millera664e872000-04-16 11:52:47 +100047{
Damien Millera664e872000-04-16 11:52:47 +100048 DSA_SIG *sig;
49 EVP_MD *evp_md = EVP_sha1();
50 EVP_MD_CTX md;
Ben Lindstromc66d4362001-06-09 01:36:21 +000051 u_char *digest, *ret, sigblob[SIGBLOB_LEN];
52 u_int rlen, slen, len, dlen;
Damien Millera664e872000-04-16 11:52:47 +100053 Buffer b;
54
55 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
Damien Miller0bc1bd82000-11-13 22:57:25 +110056 error("ssh_dss_sign: no DSA key");
Damien Millera664e872000-04-16 11:52:47 +100057 return -1;
58 }
Ben Lindstrom226cfa02001-01-22 05:34:40 +000059 dlen = evp_md->md_size;
60 digest = xmalloc(dlen);
Damien Millera664e872000-04-16 11:52:47 +100061 EVP_DigestInit(&md, evp_md);
Damien Millereba71ba2000-04-29 23:57:08 +100062 EVP_DigestUpdate(&md, data, datalen);
Damien Millera664e872000-04-16 11:52:47 +100063 EVP_DigestFinal(&md, digest, NULL);
64
Ben Lindstrom226cfa02001-01-22 05:34:40 +000065 sig = DSA_do_sign(digest, dlen, key->dsa);
Ben Lindstromc66d4362001-06-09 01:36:21 +000066
Ben Lindstrom226cfa02001-01-22 05:34:40 +000067 memset(digest, 0, dlen);
68 xfree(digest);
Ben Lindstromc66d4362001-06-09 01:36:21 +000069 if (sig == NULL) {
70 error("ssh_dss_sign: sign failed");
71 return -1;
72 }
Damien Millera664e872000-04-16 11:52:47 +100073
74 rlen = BN_num_bytes(sig->r);
75 slen = BN_num_bytes(sig->s);
76 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
77 error("bad sig size %d %d", rlen, slen);
78 DSA_SIG_free(sig);
79 return -1;
80 }
Damien Millera664e872000-04-16 11:52:47 +100081 memset(sigblob, 0, SIGBLOB_LEN);
82 BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
83 BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
84 DSA_SIG_free(sig);
85
Damien Miller30c3d422000-05-09 11:02:59 +100086 if (datafellows & SSH_BUG_SIGBLOB) {
Damien Millera664e872000-04-16 11:52:47 +100087 ret = xmalloc(SIGBLOB_LEN);
88 memcpy(ret, sigblob, SIGBLOB_LEN);
89 if (lenp != NULL)
90 *lenp = SIGBLOB_LEN;
91 if (sigp != NULL)
92 *sigp = ret;
93 } else {
94 /* ietf-drafts */
95 buffer_init(&b);
Damien Miller0bc1bd82000-11-13 22:57:25 +110096 buffer_put_cstring(&b, "ssh-dss");
Damien Millera664e872000-04-16 11:52:47 +100097 buffer_put_string(&b, sigblob, SIGBLOB_LEN);
98 len = buffer_len(&b);
99 ret = xmalloc(len);
100 memcpy(ret, buffer_ptr(&b), len);
101 buffer_free(&b);
102 if (lenp != NULL)
103 *lenp = len;
104 if (sigp != NULL)
105 *sigp = ret;
106 }
107 return 0;
108}
109int
Damien Miller0bc1bd82000-11-13 22:57:25 +1100110ssh_dss_verify(
Damien Millera664e872000-04-16 11:52:47 +1000111 Key *key,
Ben Lindstrom46c16222000-12-22 01:43:59 +0000112 u_char *signature, int signaturelen,
113 u_char *data, int datalen)
Damien Millera664e872000-04-16 11:52:47 +1000114{
Damien Millera664e872000-04-16 11:52:47 +1000115 DSA_SIG *sig;
116 EVP_MD *evp_md = EVP_sha1();
117 EVP_MD_CTX md;
Ben Lindstromc66d4362001-06-09 01:36:21 +0000118 u_char *digest, *sigblob;
Ben Lindstrom46c16222000-12-22 01:43:59 +0000119 u_int len, dlen;
Ben Lindstromc66d4362001-06-09 01:36:21 +0000120 int rlen, ret;
121 Buffer b;
Damien Millera664e872000-04-16 11:52:47 +1000122
123 if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
Damien Miller0bc1bd82000-11-13 22:57:25 +1100124 error("ssh_dss_verify: no DSA key");
Damien Millera664e872000-04-16 11:52:47 +1000125 return -1;
126 }
127
Damien Millera664e872000-04-16 11:52:47 +1000128 /* fetch signature */
Damien Miller30c3d422000-05-09 11:02:59 +1000129 if (datafellows & SSH_BUG_SIGBLOB) {
Damien Millera664e872000-04-16 11:52:47 +1000130 sigblob = signature;
131 len = signaturelen;
132 } else {
133 /* ietf-drafts */
Damien Miller6536c7d2000-06-22 21:32:31 +1000134 char *ktype;
Damien Millera664e872000-04-16 11:52:47 +1000135 buffer_init(&b);
Ben Lindstrom9e0ddd42001-09-18 05:41:19 +0000136 buffer_append(&b, signature, signaturelen);
Damien Millera664e872000-04-16 11:52:47 +1000137 ktype = buffer_get_string(&b, NULL);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100138 if (strcmp("ssh-dss", ktype) != 0) {
139 error("ssh_dss_verify: cannot handle type %s", ktype);
Damien Miller6536c7d2000-06-22 21:32:31 +1000140 buffer_free(&b);
141 return -1;
142 }
Ben Lindstrom9e0ddd42001-09-18 05:41:19 +0000143 sigblob = buffer_get_string(&b, &len);
Damien Millera664e872000-04-16 11:52:47 +1000144 rlen = buffer_len(&b);
Damien Miller6536c7d2000-06-22 21:32:31 +1000145 if(rlen != 0) {
Damien Millera664e872000-04-16 11:52:47 +1000146 error("remaining bytes in signature %d", rlen);
Damien Miller6536c7d2000-06-22 21:32:31 +1000147 buffer_free(&b);
148 return -1;
149 }
Damien Millera664e872000-04-16 11:52:47 +1000150 buffer_free(&b);
Damien Miller6536c7d2000-06-22 21:32:31 +1000151 xfree(ktype);
Damien Millera664e872000-04-16 11:52:47 +1000152 }
153
154 if (len != SIGBLOB_LEN) {
155 fatal("bad sigbloblen %d != SIGBLOB_LEN", len);
156 }
157
158 /* parse signature */
159 sig = DSA_SIG_new();
160 sig->r = BN_new();
161 sig->s = BN_new();
162 BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
163 BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
Damien Miller30c3d422000-05-09 11:02:59 +1000164
165 if (!(datafellows & SSH_BUG_SIGBLOB)) {
Damien Millera664e872000-04-16 11:52:47 +1000166 memset(sigblob, 0, len);
167 xfree(sigblob);
168 }
Kevin Stevesef4eea92001-02-05 12:42:17 +0000169
Damien Millereba71ba2000-04-29 23:57:08 +1000170 /* sha1 the data */
Damien Miller0bc1bd82000-11-13 22:57:25 +1100171 dlen = evp_md->md_size;
172 digest = xmalloc(dlen);
Damien Millera664e872000-04-16 11:52:47 +1000173 EVP_DigestInit(&md, evp_md);
Damien Millereba71ba2000-04-29 23:57:08 +1000174 EVP_DigestUpdate(&md, data, datalen);
Damien Millera664e872000-04-16 11:52:47 +1000175 EVP_DigestFinal(&md, digest, NULL);
176
Damien Miller0bc1bd82000-11-13 22:57:25 +1100177 ret = DSA_do_verify(digest, dlen, sig, key->dsa);
Damien Millera664e872000-04-16 11:52:47 +1000178
Damien Miller0bc1bd82000-11-13 22:57:25 +1100179 memset(digest, 0, dlen);
Damien Millera664e872000-04-16 11:52:47 +1000180 xfree(digest);
181 DSA_SIG_free(sig);
182
Ben Lindstromc66d4362001-06-09 01:36:21 +0000183 debug("ssh_dss_verify: signature %s",
184 ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
Damien Millera664e872000-04-16 11:52:47 +1000185 return ret;
186}