Annotation of src/usr.bin/ssh/ssh-rsa.c, Revision 1.23
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"
1.23 ! markus 26: RCSID("$OpenBSD: ssh-rsa.c,v 1.22 2002/07/04 04:15:33 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;
1.23 ! markus 47: u_char digest[EVP_MAX_MD_SIZE], *sig;
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);
1.23 ! markus 93: if (lenp != NULL)
! 94: *lenp = len;
! 95: if (sigp != NULL) {
! 96: *sigp = xmalloc(len);
! 97: memcpy(*sigp, buffer_ptr(&b), len);
! 98: }
1.1 markus 99: buffer_free(&b);
100: memset(sig, 's', slen);
101: xfree(sig);
102:
103: return 0;
104: }
105:
106: int
1.21 deraadt 107: ssh_rsa_verify(Key *key, u_char *signature, u_int signaturelen,
1.16 markus 108: u_char *data, u_int datalen)
1.1 markus 109: {
110: Buffer b;
1.7 markus 111: const EVP_MD *evp_md;
1.1 markus 112: EVP_MD_CTX md;
113: char *ktype;
1.15 markus 114: u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1.19 markus 115: u_int len, dlen, modlen;
1.7 markus 116: int rlen, ret, nid;
1.1 markus 117:
118: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
119: error("ssh_rsa_verify: no RSA key");
1.4 markus 120: return -1;
121: }
1.17 stevesk 122: if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {
1.20 stevesk 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);
1.1 markus 125: return -1;
126: }
127: buffer_init(&b);
1.10 stevesk 128: buffer_append(&b, signature, signaturelen);
1.1 markus 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);
1.10 stevesk 137: sigblob = buffer_get_string(&b, &len);
1.1 markus 138: rlen = buffer_len(&b);
139: buffer_free(&b);
1.14 deraadt 140: if (rlen != 0) {
1.12 markus 141: error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
1.7 markus 142: xfree(sigblob);
1.1 markus 143: return -1;
1.19 markus 144: }
145: /* RSA_verify expects a signature of RSA_size */
146: modlen = RSA_size(key->rsa);
147: if (len > modlen) {
1.21 deraadt 148: error("ssh_rsa_verify: len %u > modlen %u", len, modlen);
1.19 markus 149: xfree(sigblob);
150: return -1;
151: } else if (len < modlen) {
152: int diff = modlen - len;
1.21 deraadt 153: debug("ssh_rsa_verify: add padding: modlen %u > len %u",
1.19 markus 154: modlen, len);
155: sigblob = xrealloc(sigblob, modlen);
156: memmove(sigblob + diff, sigblob, len);
157: memset(sigblob, 0, diff);
158: len = modlen;
1.1 markus 159: }
1.8 markus 160: nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1.7 markus 161: if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
1.12 markus 162: error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
1.7 markus 163: xfree(sigblob);
164: return -1;
165: }
1.1 markus 166: EVP_DigestInit(&md, evp_md);
167: EVP_DigestUpdate(&md, data, datalen);
1.15 markus 168: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 169:
1.7 markus 170: ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
1.15 markus 171: memset(digest, 'd', sizeof(digest));
1.1 markus 172: memset(sigblob, 's', len);
173: xfree(sigblob);
174: if (ret == 0) {
175: int ecode = ERR_get_error();
1.21 deraadt 176: error("ssh_rsa_verify: RSA_verify failed: %s",
177: ERR_error_string(ecode, NULL));
1.1 markus 178: }
179: debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
180: return ret;
181: }
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