Annotation of src/usr.bin/ssh/ssh-dss.c, Revision 1.38
1.38 ! djm 1: /* $OpenBSD: ssh-dss.c,v 1.37 2018/02/07 02:06:51 jsing 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;
1.38 ! djm 48: const BIGNUM *sig_r, *sig_s;
1.30 djm 49: u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
1.32 djm 50: size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
51: struct sshbuf *b = NULL;
52: int ret = SSH_ERR_INVALID_ARGUMENT;
53:
54: if (lenp != NULL)
55: *lenp = 0;
56: if (sigp != NULL)
57: *sigp = NULL;
58:
59: if (key == NULL || key->dsa == NULL ||
60: sshkey_type_plain(key->type) != KEY_DSA)
61: return SSH_ERR_INVALID_ARGUMENT;
62: if (dlen == 0)
63: return SSH_ERR_INTERNAL_ERROR;
64:
65: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
66: digest, sizeof(digest))) != 0)
67: goto out;
68:
69: if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
70: ret = SSH_ERR_LIBCRYPTO_ERROR;
71: goto out;
1.1 markus 72: }
73:
1.38 ! djm 74: DSA_SIG_get0(sig, &sig_r, &sig_s);
! 75: rlen = BN_num_bytes(sig_r);
! 76: slen = BN_num_bytes(sig_s);
1.1 markus 77: if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
1.32 djm 78: ret = SSH_ERR_INTERNAL_ERROR;
79: goto out;
1.1 markus 80: }
1.31 djm 81: explicit_bzero(sigblob, SIGBLOB_LEN);
1.38 ! djm 82: BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
! 83: BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
1.1 markus 84:
1.36 djm 85: if ((b = sshbuf_new()) == NULL) {
86: ret = SSH_ERR_ALLOC_FAIL;
87: goto out;
88: }
89: if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
90: (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
91: goto out;
92:
93: len = sshbuf_len(b);
94: if (sigp != NULL) {
95: if ((*sigp = malloc(len)) == NULL) {
1.32 djm 96: ret = SSH_ERR_ALLOC_FAIL;
97: goto out;
98: }
1.36 djm 99: memcpy(*sigp, sshbuf_ptr(b), len);
1.1 markus 100: }
1.36 djm 101: if (lenp != NULL)
102: *lenp = len;
103: ret = 0;
1.32 djm 104: out:
105: explicit_bzero(digest, sizeof(digest));
1.37 jsing 106: DSA_SIG_free(sig);
1.34 mmcc 107: sshbuf_free(b);
1.32 djm 108: return ret;
1.1 markus 109: }
1.32 djm 110:
1.1 markus 111: int
1.32 djm 112: ssh_dss_verify(const struct sshkey *key,
113: const u_char *signature, size_t signaturelen,
114: const u_char *data, size_t datalen, u_int compat)
1.1 markus 115: {
1.32 djm 116: DSA_SIG *sig = NULL;
1.38 ! djm 117: BIGNUM *sig_r = NULL, *sig_s = NULL;
1.32 djm 118: u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
119: size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
120: int ret = SSH_ERR_INTERNAL_ERROR;
121: struct sshbuf *b = NULL;
122: char *ktype = NULL;
123:
124: if (key == NULL || key->dsa == NULL ||
1.35 djm 125: sshkey_type_plain(key->type) != KEY_DSA ||
126: signature == NULL || signaturelen == 0)
1.32 djm 127: return SSH_ERR_INVALID_ARGUMENT;
128: if (dlen == 0)
129: return SSH_ERR_INTERNAL_ERROR;
1.1 markus 130:
131: /* fetch signature */
1.36 djm 132: if ((b = sshbuf_from(signature, signaturelen)) == NULL)
133: return SSH_ERR_ALLOC_FAIL;
134: if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
135: sshbuf_get_string(b, &sigblob, &len) != 0) {
136: ret = SSH_ERR_INVALID_FORMAT;
137: goto out;
138: }
139: if (strcmp("ssh-dss", ktype) != 0) {
140: ret = SSH_ERR_KEY_TYPE_MISMATCH;
141: goto out;
142: }
143: if (sshbuf_len(b) != 0) {
144: ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
145: goto out;
1.1 markus 146: }
147:
148: if (len != SIGBLOB_LEN) {
1.32 djm 149: ret = SSH_ERR_INVALID_FORMAT;
150: goto out;
1.1 markus 151: }
152:
153: /* parse signature */
1.32 djm 154: if ((sig = DSA_SIG_new()) == NULL ||
1.38 ! djm 155: (sig_r = BN_new()) == NULL ||
! 156: (sig_s = BN_new()) == NULL) {
1.32 djm 157: ret = SSH_ERR_ALLOC_FAIL;
158: goto out;
159: }
1.38 ! djm 160: if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
! 161: (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
1.32 djm 162: ret = SSH_ERR_LIBCRYPTO_ERROR;
163: goto out;
164: }
1.38 ! djm 165: if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
! 166: ret = SSH_ERR_LIBCRYPTO_ERROR;
! 167: goto out;
! 168: }
! 169: sig_r = sig_s = NULL; /* transferred */
1.5 stevesk 170:
1.1 markus 171: /* sha1 the data */
1.32 djm 172: if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
173: digest, sizeof(digest))) != 0)
174: goto out;
175:
176: switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
177: case 1:
178: ret = 0;
179: break;
180: case 0:
181: ret = SSH_ERR_SIGNATURE_INVALID;
182: goto out;
183: default:
184: ret = SSH_ERR_LIBCRYPTO_ERROR;
185: goto out;
1.30 djm 186: }
1.1 markus 187:
1.32 djm 188: out:
1.31 djm 189: explicit_bzero(digest, sizeof(digest));
1.37 jsing 190: DSA_SIG_free(sig);
1.38 ! djm 191: BN_clear_free(sig_r);
! 192: BN_clear_free(sig_s);
1.34 mmcc 193: sshbuf_free(b);
1.33 mmcc 194: free(ktype);
1.32 djm 195: if (sigblob != NULL) {
196: explicit_bzero(sigblob, len);
197: free(sigblob);
198: }
1.1 markus 199: return ret;
200: }
![[BACK]](/icons/back.gif){kind=icon}
Return to ssh-dss.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh