Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.33
1.33 ! mmcc 1: /* $OpenBSD: ssh-dss.c,v 1.32 2014/06/24 01:13:21 djm Exp $ */
1.1 markus 2: /*
3: * Copyright (c) 2000 Markus Friedl. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24: */
25:
1.23 deraadt 26: #include <sys/types.h>
1.4 markus 27:
28: #include <openssl/bn.h>
29: #include <openssl/evp.h>
1.22 stevesk 30:
31: #include <string.h>
1.1 markus 32:
1.32 djm 33: #include "sshbuf.h"
1.1 markus 34: #include "compat.h"
1.32 djm 35: #include "ssherr.h"
1.30 djm 36: #include "digest.h"
1.32 djm 37: #define SSHKEY_INTERNAL
38: #include "sshkey.h"
1.1 markus 39:
40: #define INTBLOB_LEN 20
41: #define SIGBLOB_LEN (2*INTBLOB_LEN)
42:
43: int
1.32 djm 44: ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
45: const u_char *data, size_t datalen, u_int compat)
1.1 markus 46: {
1.32 djm 47: DSA_SIG *sig = NULL;
1.30 djm 48: u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
1.32 djm 49: size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
50: struct sshbuf *b = NULL;
51: int ret = SSH_ERR_INVALID_ARGUMENT;
52:
53: if (lenp != NULL)
54: *lenp = 0;
55: if (sigp != NULL)
56: *sigp = NULL;
57:
58: if (key == NULL || key->dsa == NULL ||
59: sshkey_type_plain(key->type) != KEY_DSA)
60: return SSH_ERR_INVALID_ARGUMENT;
61: if (dlen == 0)
62: return SSH_ERR_INTERNAL_ERROR;
63:
64: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
65: digest, sizeof(digest))) != 0)
66: goto out;
67:
68: if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
69: ret = SSH_ERR_LIBCRYPTO_ERROR;
70: goto out;
1.1 markus 71: }
72:
73: rlen = BN_num_bytes(sig->r);
74: slen = BN_num_bytes(sig->s);
75: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.32 djm 76: ret = SSH_ERR_INTERNAL_ERROR;
77: goto out;
1.1 markus 78: }
1.31 djm 79: explicit_bzero(sigblob, SIGBLOB_LEN);
1.32 djm 80: BN_bn2bin(sig->r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
81: BN_bn2bin(sig->s, sigblob + SIGBLOB_LEN - slen);
1.1 markus 82:
1.32 djm 83: if (compat & SSH_BUG_SIGBLOB) {
1.17 markus 84: if (sigp != NULL) {
1.32 djm 85: if ((*sigp = malloc(SIGBLOB_LEN)) == NULL) {
86: ret = SSH_ERR_ALLOC_FAIL;
87: goto out;
88: }
1.17 markus 89: memcpy(*sigp, sigblob, SIGBLOB_LEN);
90: }
1.32 djm 91: if (lenp != NULL)
92: *lenp = SIGBLOB_LEN;
93: ret = 0;
1.1 markus 94: } else {
95: /* ietf-drafts */
1.32 djm 96: if ((b = sshbuf_new()) == NULL) {
97: ret = SSH_ERR_ALLOC_FAIL;
98: goto out;
99: }
100: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
101: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
102: goto out;
103: len = sshbuf_len(b);
104: if (sigp != NULL) {
105: if ((*sigp = malloc(len)) == NULL) {
106: ret = SSH_ERR_ALLOC_FAIL;
107: goto out;
108: }
109: memcpy(*sigp, sshbuf_ptr(b), len);
110: }
1.1 markus 111: if (lenp != NULL)
112: *lenp = len;
1.32 djm 113: ret = 0;
1.1 markus 114: }
1.32 djm 115: out:
116: explicit_bzero(digest, sizeof(digest));
117: if (sig != NULL)
118: DSA_SIG_free(sig);
119: if (b != NULL)
120: sshbuf_free(b);
121: return ret;
1.1 markus 122: }
1.32 djm 123:
1.1 markus 124: int
1.32 djm 125: ssh_dss_verify(const struct sshkey *key,
126: const u_char *signature, size_t signaturelen,
127: const u_char *data, size_t datalen, u_int compat)
1.1 markus 128: {
1.32 djm 129: DSA_SIG *sig = NULL;
130: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
131: size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
132: int ret = SSH_ERR_INTERNAL_ERROR;
133: struct sshbuf *b = NULL;
134: char *ktype = NULL;
135:
136: if (key == NULL || key->dsa == NULL ||
137: sshkey_type_plain(key->type) != KEY_DSA)
138: return SSH_ERR_INVALID_ARGUMENT;
139: if (dlen == 0)
140: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 141:
142: /* fetch signature */
1.32 djm 143: if (compat & SSH_BUG_SIGBLOB) {
144: if ((sigblob = malloc(signaturelen)) == NULL)
145: return SSH_ERR_ALLOC_FAIL;
1.19 jakob 146: memcpy(sigblob, signature, signaturelen);
1.1 markus 147: len = signaturelen;
148: } else {
149: /* ietf-drafts */
1.32 djm 150: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
151: return SSH_ERR_ALLOC_FAIL;
152: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
153: sshbuf_get_string(b, &sigblob, &len) != 0) {
154: ret = SSH_ERR_INVALID_FORMAT;
155: goto out;
156: }
1.1 markus 157: if (strcmp("ssh-dss", ktype) != 0) {
1.32 djm 158: ret = SSH_ERR_KEY_TYPE_MISMATCH;
159: goto out;
1.1 markus 160: }
1.32 djm 161: if (sshbuf_len(b) != 0) {
162: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
163: goto out;
1.1 markus 164: }
165: }
166:
167: if (len != SIGBLOB_LEN) {
1.32 djm 168: ret = SSH_ERR_INVALID_FORMAT;
169: goto out;
1.1 markus 170: }
171:
172: /* parse signature */
1.32 djm 173: if ((sig = DSA_SIG_new()) == NULL ||
174: (sig->r = BN_new()) == NULL ||
175: (sig->s = BN_new()) == NULL) {
176: ret = SSH_ERR_ALLOC_FAIL;
177: goto out;
178: }
1.24 markus 179: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) ||
1.32 djm 180: (BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL)) {
181: ret = SSH_ERR_LIBCRYPTO_ERROR;
182: goto out;
183: }
1.5 stevesk 184:
1.1 markus 185: /* sha1 the data */
1.32 djm 186: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
187: digest, sizeof(digest))) != 0)
188: goto out;
189:
190: switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
191: case 1:
192: ret = 0;
193: break;
194: case 0:
195: ret = SSH_ERR_SIGNATURE_INVALID;
196: goto out;
197: default:
198: ret = SSH_ERR_LIBCRYPTO_ERROR;
199: goto out;
1.30 djm 200: }
1.1 markus 201:
1.32 djm 202: out:
1.31 djm 203: explicit_bzero(digest, sizeof(digest));
1.32 djm 204: if (sig != NULL)
205: DSA_SIG_free(sig);
206: if (b != NULL)
207: sshbuf_free(b);
1.33 ! mmcc 208: free(ktype);
1.32 djm 209: if (sigblob != NULL) {
210: explicit_bzero(sigblob, len);
211: free(sigblob);
212: }
1.1 markus 213: return ret;
214: }
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