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fa08c86b | 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" | |
087dea86 | 26 | RCSID("$OpenBSD: ssh-rsa.c,v 1.15 2002/01/25 21:42:11 markus Exp $"); |
fa08c86b | 27 | |
28 | #include <openssl/evp.h> | |
fa08c86b | 29 | #include <openssl/err.h> |
30 | ||
42f11eb2 | 31 | #include "xmalloc.h" |
32 | #include "log.h" | |
33 | #include "buffer.h" | |
34 | #include "bufaux.h" | |
fa08c86b | 35 | #include "key.h" |
5ca51e19 | 36 | #include "ssh-rsa.h" |
a4da628b | 37 | #include "compat.h" |
fa08c86b | 38 | |
fa08c86b | 39 | /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ |
40 | int | |
41 | ssh_rsa_sign( | |
42 | Key *key, | |
1e3b8b07 | 43 | u_char **sigp, int *lenp, |
44 | u_char *data, int datalen) | |
fa08c86b | 45 | { |
1a92bd7e | 46 | const EVP_MD *evp_md; |
fa08c86b | 47 | EVP_MD_CTX md; |
087dea86 | 48 | u_char digest[EVP_MAX_MD_SIZE], *sig, *ret; |
1e3b8b07 | 49 | u_int slen, dlen, len; |
1a92bd7e | 50 | int ok, nid; |
fa08c86b | 51 | Buffer b; |
52 | ||
53 | if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { | |
54 | error("ssh_rsa_sign: no RSA key"); | |
55 | return -1; | |
56 | } | |
5d4446bf | 57 | if (datafellows & SSH_BUG_SIGBLOB) { |
10f22cd7 | 58 | error("ssh_rsa_sign: SSH_BUG_SIGBLOB not supported"); |
59 | return -1; | |
60 | } | |
a4da628b | 61 | nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; |
1a92bd7e | 62 | if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { |
63 | error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid); | |
64 | return -1; | |
65 | } | |
fa08c86b | 66 | EVP_DigestInit(&md, evp_md); |
67 | EVP_DigestUpdate(&md, data, datalen); | |
087dea86 | 68 | EVP_DigestFinal(&md, digest, &dlen); |
fa08c86b | 69 | |
1a92bd7e | 70 | slen = RSA_size(key->rsa); |
71 | sig = xmalloc(slen); | |
72 | ||
73 | ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa); | |
087dea86 | 74 | memset(digest, 'd', sizeof(digest)); |
fa08c86b | 75 | |
76 | if (ok != 1) { | |
77 | int ecode = ERR_get_error(); | |
78 | error("ssh_rsa_sign: RSA_sign failed: %s", ERR_error_string(ecode, NULL)); | |
79 | xfree(sig); | |
80 | return -1; | |
81 | } | |
82 | if (len < slen) { | |
83 | int diff = slen - len; | |
84 | debug("slen %d > len %d", slen, len); | |
85 | memmove(sig + diff, sig, len); | |
86 | memset(sig, 0, diff); | |
87 | } else if (len > slen) { | |
88 | error("ssh_rsa_sign: slen %d slen2 %d", slen, len); | |
89 | xfree(sig); | |
90 | return -1; | |
91 | } | |
92 | /* encode signature */ | |
93 | buffer_init(&b); | |
94 | buffer_put_cstring(&b, "ssh-rsa"); | |
95 | buffer_put_string(&b, sig, slen); | |
96 | len = buffer_len(&b); | |
97 | ret = xmalloc(len); | |
98 | memcpy(ret, buffer_ptr(&b), len); | |
99 | buffer_free(&b); | |
100 | memset(sig, 's', slen); | |
101 | xfree(sig); | |
102 | ||
103 | if (lenp != NULL) | |
104 | *lenp = len; | |
105 | if (sigp != NULL) | |
106 | *sigp = ret; | |
fa08c86b | 107 | return 0; |
108 | } | |
109 | ||
110 | int | |
111 | ssh_rsa_verify( | |
112 | Key *key, | |
1e3b8b07 | 113 | u_char *signature, int signaturelen, |
114 | u_char *data, int datalen) | |
fa08c86b | 115 | { |
116 | Buffer b; | |
1a92bd7e | 117 | const EVP_MD *evp_md; |
fa08c86b | 118 | EVP_MD_CTX md; |
119 | char *ktype; | |
087dea86 | 120 | u_char digest[EVP_MAX_MD_SIZE], *sigblob; |
1e3b8b07 | 121 | u_int len, dlen; |
1a92bd7e | 122 | int rlen, ret, nid; |
fa08c86b | 123 | |
124 | if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) { | |
125 | error("ssh_rsa_verify: no RSA key"); | |
126 | return -1; | |
127 | } | |
5d4446bf | 128 | if (datafellows & SSH_BUG_SIGBLOB) { |
10f22cd7 | 129 | error("ssh_rsa_verify: SSH_BUG_SIGBLOB not supported"); |
130 | return -1; | |
131 | } | |
b5c334cc | 132 | if (BN_num_bits(key->rsa->n) < 768) { |
133 | error("ssh_rsa_verify: n too small: %d bits", | |
134 | BN_num_bits(key->rsa->n)); | |
135 | return -1; | |
136 | } | |
fa08c86b | 137 | buffer_init(&b); |
cf54363d | 138 | buffer_append(&b, signature, signaturelen); |
fa08c86b | 139 | ktype = buffer_get_string(&b, NULL); |
140 | if (strcmp("ssh-rsa", ktype) != 0) { | |
141 | error("ssh_rsa_verify: cannot handle type %s", ktype); | |
142 | buffer_free(&b); | |
143 | xfree(ktype); | |
144 | return -1; | |
145 | } | |
146 | xfree(ktype); | |
cf54363d | 147 | sigblob = buffer_get_string(&b, &len); |
fa08c86b | 148 | rlen = buffer_len(&b); |
149 | buffer_free(&b); | |
6aacefa7 | 150 | if (rlen != 0) { |
fa08c86b | 151 | error("ssh_rsa_verify: remaining bytes in signature %d", rlen); |
abc4e9a7 | 152 | xfree(sigblob); |
fa08c86b | 153 | return -1; |
154 | } | |
a4da628b | 155 | nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1; |
1a92bd7e | 156 | if ((evp_md = EVP_get_digestbynid(nid)) == NULL) { |
1a92bd7e | 157 | error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid); |
abc4e9a7 | 158 | xfree(sigblob); |
1a92bd7e | 159 | return -1; |
160 | } | |
fa08c86b | 161 | EVP_DigestInit(&md, evp_md); |
162 | EVP_DigestUpdate(&md, data, datalen); | |
087dea86 | 163 | EVP_DigestFinal(&md, digest, &dlen); |
fa08c86b | 164 | |
1a92bd7e | 165 | ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa); |
087dea86 | 166 | memset(digest, 'd', sizeof(digest)); |
fa08c86b | 167 | memset(sigblob, 's', len); |
168 | xfree(sigblob); | |
169 | if (ret == 0) { | |
170 | int ecode = ERR_get_error(); | |
171 | error("ssh_rsa_verify: RSA_verify failed: %s", ERR_error_string(ecode, NULL)); | |
172 | } | |
173 | debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : ""); | |
174 | return ret; | |
175 | } |