1 /* $OpenBSD: ssh-dss.c,v 1.32 2014/06/24 01:13:21 djm Exp $ */
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
30 #include <sys/types.h>
32 #include <openssl/bn.h>
33 #include <openssl/dsa.h>
34 #include <openssl/evp.h>
43 #define SSHKEY_INTERNAL
46 #define INTBLOB_LEN 20
47 #define SIGBLOB_LEN (2*INTBLOB_LEN)
50 ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
51 const u_char *data, size_t datalen, u_int compat)
54 u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
55 size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
56 struct sshbuf *b = NULL;
57 int ret = SSH_ERR_INVALID_ARGUMENT;
64 if (key == NULL || key->dsa == NULL ||
65 sshkey_type_plain(key->type) != KEY_DSA)
66 return SSH_ERR_INVALID_ARGUMENT;
68 return SSH_ERR_INTERNAL_ERROR;
70 if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
71 digest, sizeof(digest))) != 0)
74 if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
75 ret = SSH_ERR_LIBCRYPTO_ERROR;
79 rlen = BN_num_bytes(sig->r);
80 slen = BN_num_bytes(sig->s);
81 if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
82 ret = SSH_ERR_INTERNAL_ERROR;
85 explicit_bzero(sigblob, SIGBLOB_LEN);
86 BN_bn2bin(sig->r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
87 BN_bn2bin(sig->s, sigblob + SIGBLOB_LEN - slen);
89 if (compat & SSH_BUG_SIGBLOB) {
91 if ((*sigp = malloc(SIGBLOB_LEN)) == NULL) {
92 ret = SSH_ERR_ALLOC_FAIL;
95 memcpy(*sigp, sigblob, SIGBLOB_LEN);
102 if ((b = sshbuf_new()) == NULL) {
103 ret = SSH_ERR_ALLOC_FAIL;
106 if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
107 (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
111 if ((*sigp = malloc(len)) == NULL) {
112 ret = SSH_ERR_ALLOC_FAIL;
115 memcpy(*sigp, sshbuf_ptr(b), len);
122 explicit_bzero(digest, sizeof(digest));
131 ssh_dss_verify(const struct sshkey *key,
132 const u_char *signature, size_t signaturelen,
133 const u_char *data, size_t datalen, u_int compat)
136 u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
137 size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
138 int ret = SSH_ERR_INTERNAL_ERROR;
139 struct sshbuf *b = NULL;
142 if (key == NULL || key->dsa == NULL ||
143 sshkey_type_plain(key->type) != KEY_DSA)
144 return SSH_ERR_INVALID_ARGUMENT;
146 return SSH_ERR_INTERNAL_ERROR;
148 /* fetch signature */
149 if (compat & SSH_BUG_SIGBLOB) {
150 if ((sigblob = malloc(signaturelen)) == NULL)
151 return SSH_ERR_ALLOC_FAIL;
152 memcpy(sigblob, signature, signaturelen);
156 if ((b = sshbuf_from(signature, signaturelen)) == NULL)
157 return SSH_ERR_ALLOC_FAIL;
158 if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
159 sshbuf_get_string(b, &sigblob, &len) != 0) {
160 ret = SSH_ERR_INVALID_FORMAT;
163 if (strcmp("ssh-dss", ktype) != 0) {
164 ret = SSH_ERR_KEY_TYPE_MISMATCH;
167 if (sshbuf_len(b) != 0) {
168 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
173 if (len != SIGBLOB_LEN) {
174 ret = SSH_ERR_INVALID_FORMAT;
178 /* parse signature */
179 if ((sig = DSA_SIG_new()) == NULL ||
180 (sig->r = BN_new()) == NULL ||
181 (sig->s = BN_new()) == NULL) {
182 ret = SSH_ERR_ALLOC_FAIL;
185 if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) ||
186 (BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL)) {
187 ret = SSH_ERR_LIBCRYPTO_ERROR;
192 if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
193 digest, sizeof(digest))) != 0)
196 switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
201 ret = SSH_ERR_SIGNATURE_INVALID;
204 ret = SSH_ERR_LIBCRYPTO_ERROR;
209 explicit_bzero(digest, sizeof(digest));
216 if (sigblob != NULL) {
217 explicit_bzero(sigblob, len);
222 #endif /* WITH_OPENSSL */