Annotation of src/usr.bin/ssh/ssh-rsa.c, Revision 1.8
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"
1.8 ! markus 26: RCSID("$OpenBSD: ssh-rsa.c,v 1.7 2001/03/27 10:34:08 markus 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"
1.1 markus 38:
39: /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
40: int
41: ssh_rsa_sign(
42: Key *key,
1.2 markus 43: u_char **sigp, int *lenp,
44: u_char *data, int datalen)
1.1 markus 45: {
1.7 markus 46: const EVP_MD *evp_md;
1.1 markus 47: EVP_MD_CTX md;
1.2 markus 48: u_char *digest, *sig, *ret;
49: u_int slen, dlen, len;
1.7 markus 50: int ok, nid;
1.1 markus 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: }
1.8 ! markus 57: nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1.7 markus 58: if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
59: error("ssh_rsa_sign: EVP_get_digestbynid %d failed", nid);
60: return -1;
61: }
1.1 markus 62: dlen = evp_md->md_size;
63: digest = xmalloc(dlen);
64: EVP_DigestInit(&md, evp_md);
65: EVP_DigestUpdate(&md, data, datalen);
66: EVP_DigestFinal(&md, digest, NULL);
67:
1.7 markus 68: slen = RSA_size(key->rsa);
69: sig = xmalloc(slen);
70:
71: ok = RSA_sign(nid, digest, dlen, sig, &len, key->rsa);
1.1 markus 72: memset(digest, 'd', dlen);
73: xfree(digest);
74:
75: if (ok != 1) {
76: int ecode = ERR_get_error();
77: error("ssh_rsa_sign: RSA_sign failed: %s", ERR_error_string(ecode, NULL));
78: xfree(sig);
79: return -1;
80: }
81: if (len < slen) {
82: int diff = slen - len;
83: debug("slen %d > len %d", slen, len);
84: memmove(sig + diff, sig, len);
85: memset(sig, 0, diff);
86: } else if (len > slen) {
87: error("ssh_rsa_sign: slen %d slen2 %d", slen, len);
88: xfree(sig);
89: return -1;
90: }
91: /* encode signature */
92: buffer_init(&b);
93: buffer_put_cstring(&b, "ssh-rsa");
94: buffer_put_string(&b, sig, slen);
95: len = buffer_len(&b);
96: ret = xmalloc(len);
97: memcpy(ret, buffer_ptr(&b), len);
98: buffer_free(&b);
99: memset(sig, 's', slen);
100: xfree(sig);
101:
102: if (lenp != NULL)
103: *lenp = len;
104: if (sigp != NULL)
105: *sigp = ret;
106: debug2("ssh_rsa_sign: done");
107: return 0;
108: }
109:
110: int
111: ssh_rsa_verify(
112: Key *key,
1.2 markus 113: u_char *signature, int signaturelen,
114: u_char *data, int datalen)
1.1 markus 115: {
116: Buffer b;
1.7 markus 117: const EVP_MD *evp_md;
1.1 markus 118: EVP_MD_CTX md;
119: char *ktype;
1.2 markus 120: u_char *sigblob, *digest;
121: u_int len, dlen;
1.7 markus 122: int rlen, ret, nid;
1.1 markus 123:
124: if (key == NULL || key->type != KEY_RSA || key->rsa == NULL) {
125: error("ssh_rsa_verify: no RSA key");
1.4 markus 126: return -1;
127: }
128: if (BN_num_bits(key->rsa->n) < 768) {
129: error("ssh_rsa_verify: n too small: %d bits",
130: BN_num_bits(key->rsa->n));
1.1 markus 131: return -1;
132: }
133: buffer_init(&b);
134: buffer_append(&b, (char *) signature, signaturelen);
135: ktype = buffer_get_string(&b, NULL);
136: if (strcmp("ssh-rsa", ktype) != 0) {
137: error("ssh_rsa_verify: cannot handle type %s", ktype);
138: buffer_free(&b);
139: xfree(ktype);
140: return -1;
141: }
142: xfree(ktype);
1.2 markus 143: sigblob = (u_char *)buffer_get_string(&b, &len);
1.1 markus 144: rlen = buffer_len(&b);
145: buffer_free(&b);
146: if(rlen != 0) {
1.7 markus 147: xfree(sigblob);
1.1 markus 148: error("ssh_rsa_verify: remaining bytes in signature %d", rlen);
149: return -1;
150: }
1.8 ! markus 151: nid = (datafellows & SSH_BUG_RSASIGMD5) ? NID_md5 : NID_sha1;
1.7 markus 152: if ((evp_md = EVP_get_digestbynid(nid)) == NULL) {
153: xfree(sigblob);
154: error("ssh_rsa_verify: EVP_get_digestbynid %d failed", nid);
155: return -1;
156: }
1.1 markus 157: dlen = evp_md->md_size;
158: digest = xmalloc(dlen);
159: EVP_DigestInit(&md, evp_md);
160: EVP_DigestUpdate(&md, data, datalen);
161: EVP_DigestFinal(&md, digest, NULL);
162:
1.7 markus 163: ret = RSA_verify(nid, digest, dlen, sigblob, len, key->rsa);
1.1 markus 164: memset(digest, 'd', dlen);
165: xfree(digest);
166: memset(sigblob, 's', len);
167: xfree(sigblob);
168: if (ret == 0) {
169: int ecode = ERR_get_error();
170: error("ssh_rsa_verify: RSA_verify failed: %s", ERR_error_string(ecode, NULL));
171: }
172: debug("ssh_rsa_verify: signature %scorrect", (ret==0) ? "in" : "");
173: return ret;
174: }