Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.8.2.4
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"
1.8.2.4 ! miod 26: RCSID("$OpenBSD: ssh-dss.c,v 1.17 2002/07/04 10:41:47 markus Exp $");
1.4 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/evp.h>
1.1 markus 30:
31: #include "xmalloc.h"
32: #include "buffer.h"
33: #include "bufaux.h"
34: #include "compat.h"
1.4 markus 35: #include "log.h"
1.1 markus 36: #include "key.h"
1.6 itojun 37: #include "ssh-dss.h"
1.1 markus 38:
39: #define INTBLOB_LEN 20
40: #define SIGBLOB_LEN (2*INTBLOB_LEN)
41:
42: int
1.8.2.3 miod 43: ssh_dss_sign(Key *key, u_char **sigp, u_int *lenp,
1.8.2.2 jason 44: u_char *data, u_int datalen)
1.1 markus 45: {
46: DSA_SIG *sig;
1.8.2.2 jason 47: const EVP_MD *evp_md = EVP_sha1();
1.1 markus 48: EVP_MD_CTX md;
1.8.2.4 ! miod 49: u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN];
1.7 markus 50: u_int rlen, slen, len, dlen;
1.1 markus 51: Buffer b;
52:
53: if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
54: error("ssh_dss_sign: no DSA key");
55: return -1;
56: }
57: EVP_DigestInit(&md, evp_md);
58: EVP_DigestUpdate(&md, data, datalen);
1.8.2.2 jason 59: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 60:
1.3 markus 61: sig = DSA_do_sign(digest, dlen, key->dsa);
1.8.2.2 jason 62: memset(digest, 'd', sizeof(digest));
1.7 markus 63:
1.1 markus 64: if (sig == NULL) {
1.7 markus 65: error("ssh_dss_sign: sign failed");
66: return -1;
1.1 markus 67: }
68:
69: rlen = BN_num_bytes(sig->r);
70: slen = BN_num_bytes(sig->s);
71: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.8.2.3 miod 72: error("bad sig size %u %u", rlen, slen);
1.1 markus 73: DSA_SIG_free(sig);
74: return -1;
75: }
76: memset(sigblob, 0, SIGBLOB_LEN);
77: BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen);
78: BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen);
79: DSA_SIG_free(sig);
80:
81: if (datafellows & SSH_BUG_SIGBLOB) {
82: if (lenp != NULL)
83: *lenp = SIGBLOB_LEN;
1.8.2.4 ! miod 84: if (sigp != NULL) {
! 85: *sigp = xmalloc(SIGBLOB_LEN);
! 86: memcpy(*sigp, sigblob, SIGBLOB_LEN);
! 87: }
1.1 markus 88: } else {
89: /* ietf-drafts */
90: buffer_init(&b);
91: buffer_put_cstring(&b, "ssh-dss");
92: buffer_put_string(&b, sigblob, SIGBLOB_LEN);
93: len = buffer_len(&b);
94: if (lenp != NULL)
95: *lenp = len;
1.8.2.4 ! miod 96: if (sigp != NULL) {
! 97: *sigp = xmalloc(len);
! 98: memcpy(*sigp, buffer_ptr(&b), len);
! 99: }
! 100: buffer_free(&b);
1.1 markus 101: }
102: return 0;
103: }
104: int
1.8.2.3 miod 105: ssh_dss_verify(Key *key, u_char *signature, u_int signaturelen,
1.8.2.2 jason 106: u_char *data, u_int datalen)
1.1 markus 107: {
108: DSA_SIG *sig;
1.8.2.2 jason 109: const EVP_MD *evp_md = EVP_sha1();
1.1 markus 110: EVP_MD_CTX md;
1.8.2.2 jason 111: u_char digest[EVP_MAX_MD_SIZE], *sigblob;
1.2 markus 112: u_int len, dlen;
1.7 markus 113: int rlen, ret;
114: Buffer b;
1.1 markus 115:
116: if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) {
117: error("ssh_dss_verify: no DSA key");
118: return -1;
119: }
120:
121: /* fetch signature */
122: if (datafellows & SSH_BUG_SIGBLOB) {
123: sigblob = signature;
124: len = signaturelen;
125: } else {
126: /* ietf-drafts */
127: char *ktype;
128: buffer_init(&b);
1.8 stevesk 129: buffer_append(&b, signature, signaturelen);
1.1 markus 130: ktype = buffer_get_string(&b, NULL);
131: if (strcmp("ssh-dss", ktype) != 0) {
132: error("ssh_dss_verify: cannot handle type %s", ktype);
133: buffer_free(&b);
1.8.2.1 jason 134: xfree(ktype);
1.1 markus 135: return -1;
136: }
1.8.2.1 jason 137: xfree(ktype);
1.8 stevesk 138: sigblob = buffer_get_string(&b, &len);
1.1 markus 139: rlen = buffer_len(&b);
1.8.2.1 jason 140: buffer_free(&b);
1.8.2.2 jason 141: if (rlen != 0) {
1.8.2.1 jason 142: error("ssh_dss_verify: "
143: "remaining bytes in signature %d", rlen);
144: xfree(sigblob);
1.1 markus 145: return -1;
146: }
147: }
148:
149: if (len != SIGBLOB_LEN) {
1.8.2.3 miod 150: fatal("bad sigbloblen %u != SIGBLOB_LEN", len);
1.1 markus 151: }
152:
153: /* parse signature */
1.8.2.2 jason 154: if ((sig = DSA_SIG_new()) == NULL)
155: fatal("ssh_dss_verify: DSA_SIG_new failed");
156: if ((sig->r = BN_new()) == NULL)
157: fatal("ssh_dss_verify: BN_new failed");
158: if ((sig->s = BN_new()) == NULL)
159: fatal("ssh_dss_verify: BN_new failed");
1.1 markus 160: BN_bin2bn(sigblob, INTBLOB_LEN, sig->r);
161: BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s);
162:
163: if (!(datafellows & SSH_BUG_SIGBLOB)) {
164: memset(sigblob, 0, len);
165: xfree(sigblob);
166: }
1.5 stevesk 167:
1.1 markus 168: /* sha1 the data */
169: EVP_DigestInit(&md, evp_md);
170: EVP_DigestUpdate(&md, data, datalen);
1.8.2.2 jason 171: EVP_DigestFinal(&md, digest, &dlen);
1.1 markus 172:
173: ret = DSA_do_verify(digest, dlen, sig, key->dsa);
1.8.2.2 jason 174: memset(digest, 'd', sizeof(digest));
1.1 markus 175:
176: DSA_SIG_free(sig);
177:
1.7 markus 178: debug("ssh_dss_verify: signature %s",
179: ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error");
1.1 markus 180: return ret;
181: }