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.
26 RCSID("$OpenBSD: ssh-rsa.c,v 1.23 2002/07/04 10:41:47 markus Exp $");
28 #include <openssl/evp.h>
29 #include <openssl/err.h>
40 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
42 ssh_rsa_sign(Key *key, u_char **sigp, u_int *lenp,
43 u_char *data, u_int datalen)
47 u_char digest[EVP_MAX_MD_SIZE], *sig;
48 u_int slen, dlen, len;
52 if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
53 error("ssh_rsa_sign: no RSA key");
56 nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
57 if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
58 error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
61 EVP_DigestInit(&md, evp_md);
62 EVP_DigestUpdate(&md, data, datalen);
63 EVP_DigestFinal(&md, digest, &dlen);
65 slen = RSA_size(key->rsa);
68 ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
69 memset(digest, 'd', sizeof(digest));
72 int ecode = ERR_get_error();
73 error("ssh_rsa_sign: RSA_sign failed: %s",
74 ERR_error_string(ecode, NULL));
79 int diff = slen - len;
80 debug("slen %u > len %u", slen, len);
81 memmove(sig + diff, sig, len);
83 } else if (len > slen) {
84 error("ssh_rsa_sign: slen %u slen2 %u", slen, len);
88 /* encode signature */
90 buffer_put_cstring(&b, "ssh-rsa");
91 buffer_put_string(&b, sig, slen);
97 memcpy(*sigp, buffer_ptr(&b), len);
100 memset(sig, 's', slen);
107 ssh_rsa_verify(Key *key, u_char *signature, u_int signaturelen,
108 u_char *data, u_int datalen)
111 const EVP_MD *evp_md;
114 u_char digest[EVP_MAX_MD_SIZE], *sigblob;
115 u_int len, dlen, modlen;
118 if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
119 error("ssh_rsa_verify: no RSA key");
122 if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
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);
128 buffer_append(&b, signature, signaturelen);
129 ktype = buffer_get_string(&b, NULL);
130 if (strcmp("ssh-rsa", ktype) != 0) {
131 error("ssh_rsa_verify: cannot handle type %s", ktype);
137 sigblob = buffer_get_string(&b, &len);
138 rlen = buffer_len(&b);
141 error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
145 /* RSA_verify expects a signature of RSA_size */
146 modlen = RSA_size(key->rsa);
148 error("ssh_rsa_verify: len %u > modlen %u", len, modlen);
151 } else if (len < modlen) {
152 int diff = modlen - len;
153 debug("ssh_rsa_verify: add padding: modlen %u > len %u",
155 sigblob = xrealloc(sigblob, modlen);
156 memmove(sigblob + diff, sigblob, len);
157 memset(sigblob, 0, diff);
160 nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
161 if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
162 error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
166 EVP_DigestInit(&md, evp_md);
167 EVP_DigestUpdate(&md, data, datalen);
168 EVP_DigestFinal(&md, digest, &dlen);
170 ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
171 memset(digest, 'd', sizeof(digest));
172 memset(sigblob, 's', len);
175 int ecode = ERR_get_error();
176 error("ssh_rsa_verify: RSA_verify failed: %s",
177 ERR_error_string(ecode, NULL));
179 debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");