blob: 2dc34106667a4f8a709d9c1cb9aa53b37397f8d6 [file] [log] [blame]
Damien Miller0bc1bd82000-11-13 22:57:25 +11001/*
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 Lindstrom226cfa02001-01-22 05:34:40 +000026RCSID("$OpenBSD: ssh-rsa.c,v 1.5 2001/01/21 19:05:58 markus Exp $");
Damien Miller0bc1bd82000-11-13 22:57:25 +110027
28#include <openssl/evp.h>
Damien Miller0bc1bd82000-11-13 22:57:25 +110029#include <openssl/err.h>
30
Ben Lindstrom226cfa02001-01-22 05:34:40 +000031#include "xmalloc.h"
32#include "log.h"
33#include "buffer.h"
34#include "bufaux.h"
Damien Miller0bc1bd82000-11-13 22:57:25 +110035#include "key.h"
36
Damien Miller0bc1bd82000-11-13 22:57:25 +110037/* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
38int
39ssh_rsa_sign(
40 Key *key,
Ben Lindstrom46c16222000-12-22 01:43:59 +000041 u_char **sigp, int *lenp,
42 u_char *data, int datalen)
Damien Miller0bc1bd82000-11-13 22:57:25 +110043{
44 EVP_MD *evp_md = EVP_sha1();
45 EVP_MD_CTX md;
Ben Lindstrom46c16222000-12-22 01:43:59 +000046 u_char *digest, *sig, *ret;
47 u_int slen, dlen, len;
Damien Miller0bc1bd82000-11-13 22:57:25 +110048 int ok;
49 Buffer b;
50
51 if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
52 error("ssh_rsa_sign: no RSA key");
53 return -1;
54 }
55 slen = RSA_size(key->rsa);
56 sig = xmalloc(slen);
57
58 dlen = evp_md->md_size;
59 digest = xmalloc(dlen);
60 EVP_DigestInit(&md, evp_md);
61 EVP_DigestUpdate(&md, data, datalen);
62 EVP_DigestFinal(&md, digest, NULL);
63
64 ok = RSA_sign(NID_sha1, digest, dlen, sig, &len, key->rsa);
65 memset(digest, 'd', dlen);
66 xfree(digest);
67
68 if (ok != 1) {
69 int ecode = ERR_get_error();
70 error("ssh_rsa_sign: RSA_sign failed: %s", ERR_error_string(ecode, NULL));
71 xfree(sig);
72 return -1;
73 }
74 if (len < slen) {
75 int diff = slen - len;
76 debug("slen %d > len %d", slen, len);
77 memmove(sig + diff, sig, len);
78 memset(sig, 0, diff);
79 } else if (len > slen) {
80 error("ssh_rsa_sign: slen %d slen2 %d", slen, len);
81 xfree(sig);
82 return -1;
83 }
84 /* encode signature */
85 buffer_init(&b);
86 buffer_put_cstring(&b, "ssh-rsa");
87 buffer_put_string(&b, sig, slen);
88 len = buffer_len(&b);
89 ret = xmalloc(len);
90 memcpy(ret, buffer_ptr(&b), len);
91 buffer_free(&b);
92 memset(sig, 's', slen);
93 xfree(sig);
94
95 if (lenp != NULL)
96 *lenp = len;
97 if (sigp != NULL)
98 *sigp = ret;
99 debug2("ssh_rsa_sign: done");
100 return 0;
101}
102
103int
104ssh_rsa_verify(
105 Key *key,
Ben Lindstrom46c16222000-12-22 01:43:59 +0000106 u_char *signature, int signaturelen,
107 u_char *data, int datalen)
Damien Miller0bc1bd82000-11-13 22:57:25 +1100108{
109 Buffer b;
110 EVP_MD *evp_md = EVP_sha1();
111 EVP_MD_CTX md;
112 char *ktype;
Ben Lindstrom46c16222000-12-22 01:43:59 +0000113 u_char *sigblob, *digest;
114 u_int len, dlen;
Damien Miller0bc1bd82000-11-13 22:57:25 +1100115 int rlen;
116 int ret;
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 Lindstrombf555ba2001-01-18 02:04:35 +0000122 if (BN_num_bits(key->rsa->n) < 768) {
123 error("ssh_rsa_verify: n too small: %d bits",
124 BN_num_bits(key->rsa->n));
125 return -1;
126 }
Damien Miller0bc1bd82000-11-13 22:57:25 +1100127 buffer_init(&b);
128 buffer_append(&b, (char *) 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);
132 buffer_free(&b);
133 xfree(ktype);
134 return -1;
135 }
136 xfree(ktype);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000137 sigblob = (u_char *)buffer_get_string(&b, &len);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100138 rlen = buffer_len(&b);
139 buffer_free(&b);
140 if(rlen != 0) {
141 error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
142 return -1;
143 }
144
145 dlen = evp_md->md_size;
146 digest = xmalloc(dlen);
147 EVP_DigestInit(&md, evp_md);
148 EVP_DigestUpdate(&md, data, datalen);
149 EVP_DigestFinal(&md, digest, NULL);
150
151 ret = RSA_verify(NID_sha1, digest, dlen, sigblob, len, key->rsa);
152 memset(digest, 'd', dlen);
153 xfree(digest);
154 memset(sigblob, 's', len);
155 xfree(sigblob);
156 if (ret == 0) {
157 int ecode = ERR_get_error();
158 error("ssh_rsa_verify: RSA_verify failed: %s", ERR_error_string(ecode, NULL));
159 }
160 debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
161 return ret;
162}