Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.36
1.36 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.35 2016/04/21 06:08:02 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:
1.36 ! djm 83: if ((b = sshbuf_new()) == NULL) {
! 84: ret = SSH_ERR_ALLOC_FAIL;
! 85: goto out;
! 86: }
! 87: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
! 88: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
! 89: goto out;
! 90:
! 91: len = sshbuf_len(b);
! 92: if (sigp != NULL) {
! 93: if ((*sigp = malloc(len)) == NULL) {
1.32 djm 94: ret = SSH_ERR_ALLOC_FAIL;
95: goto out;
96: }
1.36 ! djm 97: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 markus 98: }
1.36 ! djm 99: if (lenp != NULL)
! 100: *lenp = len;
! 101: ret = 0;
1.32 djm 102: out:
103: explicit_bzero(digest, sizeof(digest));
104: if (sig != NULL)
105: DSA_SIG_free(sig);
1.34 mmcc 106: sshbuf_free(b);
1.32 djm 107: return ret;
1.1 markus 108: }
1.32 djm 109:
1.1 markus 110: int
1.32 djm 111: ssh_dss_verify(const struct sshkey *key,
112: const u_char *signature, size_t signaturelen,
113: const u_char *data, size_t datalen, u_int compat)
1.1 markus 114: {
1.32 djm 115: DSA_SIG *sig = NULL;
116: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
117: size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
118: int ret = SSH_ERR_INTERNAL_ERROR;
119: struct sshbuf *b = NULL;
120: char *ktype = NULL;
121:
122: if (key == NULL || key->dsa == NULL ||
1.35 djm 123: sshkey_type_plain(key->type) != KEY_DSA ||
124: signature == NULL || signaturelen == 0)
1.32 djm 125: return SSH_ERR_INVALID_ARGUMENT;
126: if (dlen == 0)
127: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 128:
129: /* fetch signature */
1.36 ! djm 130: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
! 131: return SSH_ERR_ALLOC_FAIL;
! 132: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
! 133: sshbuf_get_string(b, &sigblob, &len) != 0) {
! 134: ret = SSH_ERR_INVALID_FORMAT;
! 135: goto out;
! 136: }
! 137: if (strcmp("ssh-dss", ktype) != 0) {
! 138: ret = SSH_ERR_KEY_TYPE_MISMATCH;
! 139: goto out;
! 140: }
! 141: if (sshbuf_len(b) != 0) {
! 142: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
! 143: goto out;
1.1 markus 144: }
145:
146: if (len != SIGBLOB_LEN) {
1.32 djm 147: ret = SSH_ERR_INVALID_FORMAT;
148: goto out;
1.1 markus 149: }
150:
151: /* parse signature */
1.32 djm 152: if ((sig = DSA_SIG_new()) == NULL ||
153: (sig->r = BN_new()) == NULL ||
154: (sig->s = BN_new()) == NULL) {
155: ret = SSH_ERR_ALLOC_FAIL;
156: goto out;
157: }
1.24 markus 158: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) ||
1.32 djm 159: (BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL)) {
160: ret = SSH_ERR_LIBCRYPTO_ERROR;
161: goto out;
162: }
1.5 stevesk 163:
1.1 markus 164: /* sha1 the data */
1.32 djm 165: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
166: digest, sizeof(digest))) != 0)
167: goto out;
168:
169: switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
170: case 1:
171: ret = 0;
172: break;
173: case 0:
174: ret = SSH_ERR_SIGNATURE_INVALID;
175: goto out;
176: default:
177: ret = SSH_ERR_LIBCRYPTO_ERROR;
178: goto out;
1.30 djm 179: }
1.1 markus 180:
1.32 djm 181: out:
1.31 djm 182: explicit_bzero(digest, sizeof(digest));
1.32 djm 183: if (sig != NULL)
184: DSA_SIG_free(sig);
1.34 mmcc 185: sshbuf_free(b);
1.33 mmcc 186: free(ktype);
1.32 djm 187: if (sigblob != NULL) {
188: explicit_bzero(sigblob, len);
189: free(sigblob);
190: }
1.1 markus 191: return ret;
192: }