Annotation of src/usr.bin/ssh/ssh-rsa.c, Revision 1.22
1.1 markus 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"
1.22 ! deraadt 26: RCSID("$OpenBSD: ssh-rsa.c,v 1.21 2002/06/23 03:30:17 deraadt Exp $");
1.5 markus 27:
28: #include <openssl/evp.h>
29: #include <openssl/err.h>
1.1 markus 30:
31: #include "xmalloc.h"
1.5 markus 32: #include "log.h"
1.1 markus 33: #include "buffer.h"
34: #include "bufaux.h"
35: #include "key.h"
1.6 itojun 36: #include "ssh-rsa.h"
1.8 markus 37: #include "compat.h"
1.17 stevesk 38: #include "ssh.h"
1.1 markus 39:
40: /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
41: int
1.21 deraadt 42: ssh_rsa_sign(Key *key, u_char **sigp, u_int *lenp,
1.16 markus 43: u_char *data, u_int datalen)
1.1 markus 44: {
1.7 markus 45: const EVP_MD *evp_md;
1.1 markus 46: EVP_MD_CTX md;
1.15 markus 47: u_char digest[EVP_MAX_MD_SIZE], *sig, *ret;
1.2 markus 48: u_int slen, dlen, len;
1.7 markus 49: int ok, nid;
1.1 markus 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: }
1.8 markus 56: nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1.7 markus 57: if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
58: error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
59: return -1;
60: }
1.1 markus 61: EVP_DigestInit(&md, evp_md);
62: EVP_DigestUpdate(&md, data, datalen);
1.15 markus 63: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 64:
1.7 markus 65: slen = RSA_size(key->rsa);
66: sig = xmalloc(slen);
67:
68: ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
1.15 markus 69: memset(digest, 'd', sizeof(digest));
1.1 markus 70:
71: if (ok != 1) {
72: int ecode = ERR_get_error();
1.21 deraadt 73: error("ssh_rsa_sign: RSA_sign failed: %s",
74: ERR_error_string(ecode, NULL));
1.1 markus 75: xfree(sig);
76: return -1;
77: }
78: if (len < slen) {
79: int diff = slen - len;
1.21 deraadt 80: debug("slen %u > len %u", slen, len);
1.1 markus 81: memmove(sig + diff, sig, len);
82: memset(sig, 0, diff);
83: } else if (len > slen) {
1.21 deraadt 84: error("ssh_rsa_sign: slen %u slen2 %u", slen, len);
1.1 markus 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);
93: ret = xmalloc(len);
94: memcpy(ret, buffer_ptr(&b), len);
95: buffer_free(&b);
96: memset(sig, 's', slen);
97: xfree(sig);
98:
99: if (lenp != NULL)
100: *lenp = len;
101: if (sigp != NULL)
102: *sigp = ret;
1.22 ! deraadt 103: else
! 104: xfree(ret);
1.1 markus 105: return 0;
106: }
107:
108: int
1.21 deraadt 109: ssh_rsa_verify(Key *key, u_char *signature, u_int signaturelen,
1.16 markus 110: u_char *data, u_int datalen)
1.1 markus 111: {
112: Buffer b;
1.7 markus 113: const EVP_MD *evp_md;
1.1 markus 114: EVP_MD_CTX md;
115: char *ktype;
1.15 markus 116: u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1.19 markus 117: u_int len, dlen, modlen;
1.7 markus 118: int rlen, ret, nid;
1.1 markus 119:
120: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
121: error("ssh_rsa_verify: no RSA key");
1.4 markus 122: return -1;
123: }
1.17 stevesk 124: if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
1.20 stevesk 125: error("ssh_rsa_verify: RSA modulus too small: %d < minimum %d bits",
126: BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE);
1.1 markus 127: return -1;
128: }
129: buffer_init(&b);
1.10 stevesk 130: buffer_append(&b, signature, signaturelen);
1.1 markus 131: ktype = buffer_get_string(&b, NULL);
132: if (strcmp("ssh-rsa", ktype) != 0) {
133: error("ssh_rsa_verify: cannot handle type %s", ktype);
134: buffer_free(&b);
135: xfree(ktype);
136: return -1;
137: }
138: xfree(ktype);
1.10 stevesk 139: sigblob = buffer_get_string(&b, &len);
1.1 markus 140: rlen = buffer_len(&b);
141: buffer_free(&b);
1.14 deraadt 142: if (rlen != 0) {
1.12 markus 143: error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
1.7 markus 144: xfree(sigblob);
1.1 markus 145: return -1;
1.19 markus 146: }
147: /* RSA_verify expects a signature of RSA_size */
148: modlen = RSA_size(key->rsa);
149: if (len > modlen) {
1.21 deraadt 150: error("ssh_rsa_verify: len %u > modlen %u", len, modlen);
1.19 markus 151: xfree(sigblob);
152: return -1;
153: } else if (len < modlen) {
154: int diff = modlen - len;
1.21 deraadt 155: debug("ssh_rsa_verify: add padding: modlen %u > len %u",
1.19 markus 156: modlen, len);
157: sigblob = xrealloc(sigblob, modlen);
158: memmove(sigblob + diff, sigblob, len);
159: memset(sigblob, 0, diff);
160: len = modlen;
1.1 markus 161: }
1.8 markus 162: nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1.7 markus 163: if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
1.12 markus 164: error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
1.7 markus 165: xfree(sigblob);
166: return -1;
167: }
1.1 markus 168: EVP_DigestInit(&md, evp_md);
169: EVP_DigestUpdate(&md, data, datalen);
1.15 markus 170: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 171:
1.7 markus 172: ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
1.15 markus 173: memset(digest, 'd', sizeof(digest));
1.1 markus 174: memset(sigblob, 's', len);
175: xfree(sigblob);
176: if (ret == 0) {
177: int ecode = ERR_get_error();
1.21 deraadt 178: error("ssh_rsa_verify: RSA_verify failed: %s",
179: ERR_error_string(ecode, NULL));
1.1 markus 180: }
181: debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
182: return ret;
183: }