Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 1 | /* |
| 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. |
| 12 | * |
| 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 Lindstrom | 0e50d84 | 2002-08-20 18:39:14 +0000 | [diff] [blame^] | 26 | RCSID("$OpenBSD: ssh-rsa.c,v 1.24 2002/08/02 21:23:41 markus Exp $"); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 27 | |
| 28 | #include <openssl/evp.h> |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 29 | #include <openssl/err.h> |
| 30 | |
Ben Lindstrom | 226cfa0 | 2001-01-22 05:34:40 +0000 | [diff] [blame] | 31 | #include "xmalloc.h" |
| 32 | #include "log.h" |
| 33 | #include "buffer.h" |
| 34 | #include "bufaux.h" |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 35 | #include "key.h" |
Ben Lindstrom | 31ca54a | 2001-02-09 02:11:24 +0000 | [diff] [blame] | 36 | #include "ssh-rsa.h" |
Ben Lindstrom | 60a4381 | 2001-03-29 00:32:56 +0000 | [diff] [blame] | 37 | #include "compat.h" |
Ben Lindstrom | 03f3932 | 2002-04-02 20:43:11 +0000 | [diff] [blame] | 38 | #include "ssh.h" |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 39 | |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 40 | /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ |
| 41 | int |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 42 | ssh_rsa_sign(Key *key, u_char **sigp, u_int *lenp, |
Ben Lindstrom | 90fd814 | 2002-02-26 18:09:42 +0000 | [diff] [blame] | 43 | u_char *data, u_int datalen) |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 44 | { |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 45 | const EVP_MD *evp_md; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 46 | EVP_MD_CTX md; |
Ben Lindstrom | 2bf759c | 2002-07-07 22:13:31 +0000 | [diff] [blame] | 47 | u_char digest[EVP_MAX_MD_SIZE], *sig; |
Ben Lindstrom | 46c1622 | 2000-12-22 01:43:59 +0000 | [diff] [blame] | 48 | u_int slen, dlen, len; |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 49 | int ok, nid; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 50 | Buffer b; |
| 51 | |
| 52 | if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { |
| 53 | error("ssh_rsa_sign: no RSA key"); |
| 54 | return -1; |
| 55 | } |
Ben Lindstrom | 60a4381 | 2001-03-29 00:32:56 +0000 | [diff] [blame] | 56 | nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 57 | if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { |
| 58 | error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid); |
| 59 | return -1; |
| 60 | } |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 61 | EVP_DigestInit(&md, evp_md); |
| 62 | EVP_DigestUpdate(&md, data, datalen); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 63 | EVP_DigestFinal(&md, digest, &dlen); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 64 | |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 65 | slen = RSA_size(key->rsa); |
| 66 | sig = xmalloc(slen); |
| 67 | |
| 68 | ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 69 | memset(digest, 'd', sizeof(digest)); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 70 | |
| 71 | if (ok != 1) { |
| 72 | int ecode = ERR_get_error(); |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 73 | error("ssh_rsa_sign: RSA_sign failed: %s", |
| 74 | ERR_error_string(ecode, NULL)); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 75 | xfree(sig); |
| 76 | return -1; |
| 77 | } |
| 78 | if (len < slen) { |
Ben Lindstrom | 0e50d84 | 2002-08-20 18:39:14 +0000 | [diff] [blame^] | 79 | u_int diff = slen - len; |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 80 | debug("slen %u > len %u", slen, len); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 81 | memmove(sig + diff, sig, len); |
| 82 | memset(sig, 0, diff); |
| 83 | } else if (len > slen) { |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 84 | error("ssh_rsa_sign: slen %u slen2 %u", slen, len); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 85 | xfree(sig); |
| 86 | return -1; |
| 87 | } |
| 88 | /* encode signature */ |
| 89 | buffer_init(&b); |
| 90 | buffer_put_cstring(&b, "ssh-rsa"); |
| 91 | buffer_put_string(&b, sig, slen); |
| 92 | len = buffer_len(&b); |
Ben Lindstrom | 2bf759c | 2002-07-07 22:13:31 +0000 | [diff] [blame] | 93 | if (lenp != NULL) |
| 94 | *lenp = len; |
| 95 | if (sigp != NULL) { |
| 96 | *sigp = xmalloc(len); |
| 97 | memcpy(*sigp, buffer_ptr(&b), len); |
| 98 | } |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 99 | buffer_free(&b); |
| 100 | memset(sig, 's', slen); |
| 101 | xfree(sig); |
| 102 | |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 103 | return 0; |
| 104 | } |
| 105 | |
| 106 | int |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 107 | ssh_rsa_verify(Key *key, u_char *signature, u_int signaturelen, |
Ben Lindstrom | 90fd814 | 2002-02-26 18:09:42 +0000 | [diff] [blame] | 108 | u_char *data, u_int datalen) |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 109 | { |
| 110 | Buffer b; |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 111 | const EVP_MD *evp_md; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 112 | EVP_MD_CTX md; |
| 113 | char *ktype; |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 114 | u_char digest[EVP_MAX_MD_SIZE], *sigblob; |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 115 | u_int len, dlen, modlen; |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 116 | int rlen, ret, nid; |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 117 | |
| 118 | if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { |
| 119 | error("ssh_rsa_verify: no RSA key"); |
| 120 | return -1; |
| 121 | } |
Ben Lindstrom | 03f3932 | 2002-04-02 20:43:11 +0000 | [diff] [blame] | 122 | if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) { |
Ben Lindstrom | 2779d28 | 2002-06-11 15:47:42 +0000 | [diff] [blame] | 123 | error("ssh_rsa_verify: RSA modulus too small: %d < minimum %d bits", |
| 124 | BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE); |
Ben Lindstrom | bf555ba | 2001-01-18 02:04:35 +0000 | [diff] [blame] | 125 | return -1; |
| 126 | } |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 127 | buffer_init(&b); |
Ben Lindstrom | 9e0ddd4 | 2001-09-18 05:41:19 +0000 | [diff] [blame] | 128 | buffer_append(&b, signature, signaturelen); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 129 | ktype = buffer_get_string(&b, NULL); |
| 130 | if (strcmp("ssh-rsa", ktype) != 0) { |
| 131 | error("ssh_rsa_verify: cannot handle type %s", ktype); |
| 132 | buffer_free(&b); |
| 133 | xfree(ktype); |
| 134 | return -1; |
| 135 | } |
| 136 | xfree(ktype); |
Ben Lindstrom | 9e0ddd4 | 2001-09-18 05:41:19 +0000 | [diff] [blame] | 137 | sigblob = buffer_get_string(&b, &len); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 138 | rlen = buffer_len(&b); |
| 139 | buffer_free(&b); |
Ben Lindstrom | 1c37c6a | 2001-12-06 18:00:18 +0000 | [diff] [blame] | 140 | if (rlen != 0) { |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 141 | error("ssh_rsa_verify: remaining bytes in signature %d", rlen); |
Damien Miller | 36e603d | 2001-11-12 11:03:35 +1100 | [diff] [blame] | 142 | xfree(sigblob); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 143 | return -1; |
| 144 | } |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 145 | /* RSA_verify expects a signature of RSA_size */ |
| 146 | modlen = RSA_size(key->rsa); |
| 147 | if (len > modlen) { |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 148 | error("ssh_rsa_verify: len %u > modlen %u", len, modlen); |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 149 | xfree(sigblob); |
| 150 | return -1; |
| 151 | } else if (len < modlen) { |
Ben Lindstrom | 0e50d84 | 2002-08-20 18:39:14 +0000 | [diff] [blame^] | 152 | u_int diff = modlen - len; |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 153 | debug("ssh_rsa_verify: add padding: modlen %u > len %u", |
Ben Lindstrom | ceae9d1 | 2002-06-06 20:55:04 +0000 | [diff] [blame] | 154 | modlen, len); |
| 155 | sigblob = xrealloc(sigblob, modlen); |
| 156 | memmove(sigblob + diff, sigblob, len); |
| 157 | memset(sigblob, 0, diff); |
| 158 | len = modlen; |
| 159 | } |
Ben Lindstrom | 60a4381 | 2001-03-29 00:32:56 +0000 | [diff] [blame] | 160 | nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 161 | if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 162 | error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid); |
Damien Miller | 36e603d | 2001-11-12 11:03:35 +1100 | [diff] [blame] | 163 | xfree(sigblob); |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 164 | return -1; |
| 165 | } |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 166 | EVP_DigestInit(&md, evp_md); |
| 167 | EVP_DigestUpdate(&md, data, datalen); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 168 | EVP_DigestFinal(&md, digest, &dlen); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 169 | |
Ben Lindstrom | 425fb02 | 2001-03-29 00:31:20 +0000 | [diff] [blame] | 170 | ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa); |
Damien Miller | c516e92 | 2002-02-05 11:53:43 +1100 | [diff] [blame] | 171 | memset(digest, 'd', sizeof(digest)); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 172 | memset(sigblob, 's', len); |
| 173 | xfree(sigblob); |
| 174 | if (ret == 0) { |
| 175 | int ecode = ERR_get_error(); |
Ben Lindstrom | 5c38552 | 2002-06-23 21:23:20 +0000 | [diff] [blame] | 176 | error("ssh_rsa_verify: RSA_verify failed: %s", |
| 177 | ERR_error_string(ecode, NULL)); |
Damien Miller | 0bc1bd8 | 2000-11-13 22:57:25 +1100 | [diff] [blame] | 178 | } |
| 179 | debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : ""); |
| 180 | return ret; |
| 181 | } |