Damien Miller | e3476ed | 2006-07-24 14:13:33 +1000 | [diff] [blame] | 1 | /* $OpenBSD: ssh-dss.c,v 1.22 2006/07/22 20:48:23 stevesk Exp $ */ |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2000 Markus Friedl. All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 13 | * |
| 14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 24 | */ |
| 25 | |
| 26 | #include "includes.h" |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 27 | |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 28 | #include <openssl/bn.h> |
| 29 | #include <openssl/evp.h> |
| 30 | |
Damien Miller | e3476ed | 2006-07-24 14:13:33 +1000 | [diff] [blame] | 31 | #include <string.h> |
| 32 | |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 33 | #include "xmalloc.h" |
| 34 | #include "buffer.h" |
| 35 | #include "bufaux.h" |
| 36 | #include "compat.h" |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 37 | #include "log.h" |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 38 | #include "key.h" |
| 39 | |
| 40 | #define INTBLOB_LEN 20 |
| 41 | #define SIGBLOB_LEN (2*INTBLOB_LEN) |
| 42 | |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 43 | int |
Damien Miller | f58b58c | 2003-11-17 21:18:23 +1100 | [diff] [blame] | 44 | ssh_dss_sign(const Key *key, u_char **sigp, u_int *lenp, |
| 45 | const u_char *data, u_int datalen) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 46 | { |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 47 | DSA_SIG *sig; |
Ben Lindstrom | 80cb27d | 2002-03-05 01:33:36 +0000 | [diff] [blame] | 48 | const EVP_MD *evp_md = EVP_sha1(); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 49 | EVP_MD_CTX md; |
Ben Lindstrom | 2bf759c | 2002-07-07 22:13:31 +0000 | [diff] [blame] | 50 | u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN]; |
Ben Lindstrom | c66d436 | 2001-06-09 01:36:21 +0000 | [diff] [blame] | 51 | u_int rlen, slen, len, dlen; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 52 | Buffer b; |
| 53 | |
| 54 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 55 | error("ssh_dss_sign: no DSA key"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 56 | return -1; |
| 57 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 58 | EVP_DigestInit(&md, evp_md); |
Damien Miller | eba71ba | 2000-04-29 23:57:08 +1000 | [diff] [blame] | 59 | EVP_DigestUpdate(&md, data, datalen); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 60 | EVP_DigestFinal(&md, digest, &dlen); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 61 | |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 62 | sig = DSA_do_sign(digest, dlen, key->dsa); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 63 | memset(digest, 'd', sizeof(digest)); |
Ben Lindstrom | c66d436 | 2001-06-09 01:36:21 +0000 | [diff] [blame] | 64 | |
Ben Lindstrom | c66d436 | 2001-06-09 01:36:21 +0000 | [diff] [blame] | 65 | if (sig == NULL) { |
| 66 | error("ssh_dss_sign: sign failed"); |
| 67 | return -1; |
| 68 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 69 | |
| 70 | rlen = BN_num_bytes(sig->r); |
| 71 | slen = BN_num_bytes(sig->s); |
| 72 | if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 73 | error("bad sig size %u %u", rlen, slen); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 74 | DSA_SIG_free(sig); |
| 75 | return -1; |
| 76 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 77 | memset(sigblob, 0, SIGBLOB_LEN); |
| 78 | BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen); |
| 79 | BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen); |
| 80 | DSA_SIG_free(sig); |
| 81 | |
Damien Miller | 30c3d42 | 2000-05-09 11:02:59 +1000 | [diff] [blame] | 82 | if (datafellows & SSH_BUG_SIGBLOB) { |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 83 | if (lenp != NULL) |
| 84 | *lenp = SIGBLOB_LEN; |
Ben Lindstrom | 2bf759c | 2002-07-07 22:13:31 +0000 | [diff] [blame] | 85 | if (sigp != NULL) { |
| 86 | *sigp = xmalloc(SIGBLOB_LEN); |
| 87 | memcpy(*sigp, sigblob, SIGBLOB_LEN); |
| 88 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 89 | } else { |
| 90 | /* ietf-drafts */ |
| 91 | buffer_init(&b); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 92 | buffer_put_cstring(&b, "ssh-dss"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 93 | buffer_put_string(&b, sigblob, SIGBLOB_LEN); |
| 94 | len = buffer_len(&b); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 95 | if (lenp != NULL) |
| 96 | *lenp = len; |
Ben Lindstrom | 2bf759c | 2002-07-07 22:13:31 +0000 | [diff] [blame] | 97 | if (sigp != NULL) { |
| 98 | *sigp = xmalloc(len); |
| 99 | memcpy(*sigp, buffer_ptr(&b), len); |
| 100 | } |
| 101 | buffer_free(&b); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 102 | } |
| 103 | return 0; |
| 104 | } |
| 105 | int |
Damien Miller | f58b58c | 2003-11-17 21:18:23 +1100 | [diff] [blame] | 106 | ssh_dss_verify(const Key *key, const u_char *signature, u_int signaturelen, |
| 107 | const u_char *data, u_int datalen) |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 108 | { |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 109 | DSA_SIG *sig; |
Ben Lindstrom | 80cb27d | 2002-03-05 01:33:36 +0000 | [diff] [blame] | 110 | const EVP_MD *evp_md = EVP_sha1(); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 111 | EVP_MD_CTX md; |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 112 | u_char digest[EVP_MAX_MD_SIZE], *sigblob; |
Ben Lindstrom | 46c1622 | 2000-12-22 01:43:59 +0000 | [diff] [blame] | 113 | u_int len, dlen; |
Ben Lindstrom | c66d436 | 2001-06-09 01:36:21 +0000 | [diff] [blame] | 114 | int rlen, ret; |
| 115 | Buffer b; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 116 | |
| 117 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 118 | error("ssh_dss_verify: no DSA key"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 119 | return -1; |
| 120 | } |
| 121 | |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 122 | /* fetch signature */ |
Damien Miller | 30c3d42 | 2000-05-09 11:02:59 +1000 | [diff] [blame] | 123 | if (datafellows & SSH_BUG_SIGBLOB) { |
Damien Miller | f58b58c | 2003-11-17 21:18:23 +1100 | [diff] [blame] | 124 | sigblob = xmalloc(signaturelen); |
| 125 | memcpy(sigblob, signature, signaturelen); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 126 | len = signaturelen; |
| 127 | } else { |
| 128 | /* ietf-drafts */ |
Damien Miller | 6536c7d | 2000-06-22 21:32:31 +1000 | [diff] [blame] | 129 | char *ktype; |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 130 | buffer_init(&b); |
Ben Lindstrom | 9e0ddd4 | 2001-09-18 05:41:19 +0000 | [diff] [blame] | 131 | buffer_append(&b, signature, signaturelen); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 132 | ktype = buffer_get_string(&b, NULL); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 133 | if (strcmp("ssh-dss", ktype) != 0) { |
| 134 | error("ssh_dss_verify: cannot handle type %s", ktype); |
Damien Miller | 6536c7d | 2000-06-22 21:32:31 +1000 | [diff] [blame] | 135 | buffer_free(&b); |
Damien Miller | 36e603d | 2001-11-12 11:03:35 +1100 | [diff] [blame] | 136 | xfree(ktype); |
Damien Miller | 6536c7d | 2000-06-22 21:32:31 +1000 | [diff] [blame] | 137 | return -1; |
| 138 | } |
Damien Miller | 36e603d | 2001-11-12 11:03:35 +1100 | [diff] [blame] | 139 | xfree(ktype); |
Ben Lindstrom | 9e0ddd4 | 2001-09-18 05:41:19 +0000 | [diff] [blame] | 140 | sigblob = buffer_get_string(&b, &len); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 141 | rlen = buffer_len(&b); |
Damien Miller | 36e603d | 2001-11-12 11:03:35 +1100 | [diff] [blame] | 142 | buffer_free(&b); |
Ben Lindstrom | 1c37c6a | 2001-12-06 18:00:18 +0000 | [diff] [blame] | 143 | if (rlen != 0) { |
Damien Miller | 36e603d | 2001-11-12 11:03:35 +1100 | [diff] [blame] | 144 | error("ssh_dss_verify: " |
| 145 | "remaining bytes in signature %d", rlen); |
| 146 | xfree(sigblob); |
Damien Miller | 6536c7d | 2000-06-22 21:32:31 +1000 | [diff] [blame] | 147 | return -1; |
| 148 | } |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 149 | } |
| 150 | |
| 151 | if (len != SIGBLOB_LEN) { |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 152 | fatal("bad sigbloblen %u != SIGBLOB_LEN", len); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 153 | } |
| 154 | |
| 155 | /* parse signature */ |
Damien Miller | da75516 | 2002-01-22 23:09:22 +1100 | [diff] [blame] | 156 | if ((sig = DSA_SIG_new()) == NULL) |
| 157 | fatal("ssh_dss_verify: DSA_SIG_new failed"); |
| 158 | if ((sig->r = BN_new()) == NULL) |
| 159 | fatal("ssh_dss_verify: BN_new failed"); |
| 160 | if ((sig->s = BN_new()) == NULL) |
| 161 | fatal("ssh_dss_verify: BN_new failed"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 162 | BN_bin2bn(sigblob, INTBLOB_LEN, sig->r); |
| 163 | BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s); |
Damien Miller | 30c3d42 | 2000-05-09 11:02:59 +1000 | [diff] [blame] | 164 | |
Damien Miller | f58b58c | 2003-11-17 21:18:23 +1100 | [diff] [blame] | 165 | /* clean up */ |
| 166 | memset(sigblob, 0, len); |
| 167 | xfree(sigblob); |
Kevin Steves | ef4eea9 | 2001-02-05 12:42:17 +0000 | [diff] [blame] | 168 | |
Damien Miller | eba71ba | 2000-04-29 23:57:08 +1000 | [diff] [blame] | 169 | /* sha1 the data */ |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 170 | EVP_DigestInit(&md, evp_md); |
Damien Miller | eba71ba | 2000-04-29 23:57:08 +1000 | [diff] [blame] | 171 | EVP_DigestUpdate(&md, data, datalen); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 172 | EVP_DigestFinal(&md, digest, &dlen); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 173 | |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 174 | ret = DSA_do_verify(digest, dlen, sig, key->dsa); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 175 | memset(digest, 'd', sizeof(digest)); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 176 | |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 177 | DSA_SIG_free(sig); |
| 178 | |
Ben Lindstrom | c66d436 | 2001-06-09 01:36:21 +0000 | [diff] [blame] | 179 | debug("ssh_dss_verify: signature %s", |
| 180 | ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error"); |
Damien Miller | a664e87 | 2000-04-16 11:52:47 +1000 | [diff] [blame] | 181 | return ret; |
| 182 | } |