1 /* $OpenBSD: kexdhs.c,v 1.27 2018/04/10 00:10:49 djm Exp $ */
3 * Copyright (c) 2001 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>
36 #include <openssl/dh.h>
38 #include "openbsd-compat/openssl-compat.h"
54 static int input_kex_dh_init(int, u_int32_t, struct ssh *);
57 kexdh_server(struct ssh *ssh)
59 struct kex *kex = ssh->kex;
62 /* generate server DH public key */
63 switch (kex->kex_type) {
64 case KEX_DH_GRP1_SHA1:
65 kex->dh = dh_new_group1();
67 case KEX_DH_GRP14_SHA1:
68 case KEX_DH_GRP14_SHA256:
69 kex->dh = dh_new_group14();
71 case KEX_DH_GRP16_SHA512:
72 kex->dh = dh_new_group16();
74 case KEX_DH_GRP18_SHA512:
75 kex->dh = dh_new_group18();
78 r = SSH_ERR_INVALID_ARGUMENT;
81 if (kex->dh == NULL) {
82 r = SSH_ERR_ALLOC_FAIL;
85 if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
88 debug("expecting SSH2_MSG_KEXDH_INIT");
89 ssh_dispatch_set(ssh, SSH2_MSG_KEXDH_INIT, &input_kex_dh_init);
96 input_kex_dh_init(int type, u_int32_t seq, struct ssh *ssh)
98 struct kex *kex = ssh->kex;
99 BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
100 const BIGNUM *pub_key;
101 struct sshkey *server_host_public, *server_host_private;
102 u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
103 u_char hash[SSH_DIGEST_MAX_LENGTH];
104 size_t sbloblen, slen;
105 size_t klen = 0, hashlen;
108 if (kex->load_host_public_key == NULL ||
109 kex->load_host_private_key == NULL) {
110 r = SSH_ERR_INVALID_ARGUMENT;
113 server_host_public = kex->load_host_public_key(kex->hostkey_type,
114 kex->hostkey_nid, ssh);
115 server_host_private = kex->load_host_private_key(kex->hostkey_type,
116 kex->hostkey_nid, ssh);
117 if (server_host_public == NULL) {
118 r = SSH_ERR_NO_HOSTKEY_LOADED;
123 if ((dh_client_pub = BN_new()) == NULL) {
124 r = SSH_ERR_ALLOC_FAIL;
127 DH_get0_key(kex->dh, &pub_key, NULL);
128 if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 ||
129 (r = sshpkt_get_end(ssh)) != 0)
133 fprintf(stderr, "dh_client_pub= ");
134 BN_print_fp(stderr, dh_client_pub);
135 fprintf(stderr, "\n");
136 debug("bits %d", BN_num_bits(dh_client_pub));
137 DHparams_print_fp(stderr, kex->dh);
138 fprintf(stderr, "pub= ");
139 BN_print_fp(stderr, pub_key);
140 fprintf(stderr, "\n");
142 if (!dh_pub_is_valid(kex->dh, dh_client_pub)) {
143 sshpkt_disconnect(ssh, "bad client public DH value");
144 r = SSH_ERR_MESSAGE_INCOMPLETE;
148 klen = DH_size(kex->dh);
149 if ((kbuf = malloc(klen)) == NULL ||
150 (shared_secret = BN_new()) == NULL) {
151 r = SSH_ERR_ALLOC_FAIL;
154 if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 ||
155 BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
156 r = SSH_ERR_LIBCRYPTO_ERROR;
160 dump_digest("shared secret", kbuf, kout);
162 if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
166 hashlen = sizeof(hash);
167 if ((r = kex_dh_hash(
169 kex->client_version_string,
170 kex->server_version_string,
171 sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
172 sshbuf_ptr(kex->my), sshbuf_len(kex->my),
173 server_host_key_blob, sbloblen,
177 hash, &hashlen)) != 0)
180 /* save session id := H */
181 if (kex->session_id == NULL) {
182 kex->session_id_len = hashlen;
183 kex->session_id = malloc(kex->session_id_len);
184 if (kex->session_id == NULL) {
185 r = SSH_ERR_ALLOC_FAIL;
188 memcpy(kex->session_id, hash, kex->session_id_len);
192 if ((r = kex->sign(server_host_private, server_host_public, &signature,
193 &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
196 /* destroy_sensitive_data(); */
198 /* send server hostkey, DH pubkey 'f' and signed H */
199 if ((r = sshpkt_start(ssh, SSH2_MSG_KEXDH_REPLY)) != 0 ||
200 (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
201 (r = sshpkt_put_bignum2(ssh, pub_key)) != 0 || /* f */
202 (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
203 (r = sshpkt_send(ssh)) != 0)
206 if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
207 r = kex_send_newkeys(ssh);
209 explicit_bzero(hash, sizeof(hash));
212 BN_clear_free(dh_client_pub);
214 explicit_bzero(kbuf, klen);
217 BN_clear_free(shared_secret);
218 free(server_host_key_blob);
222 #endif /* WITH_OPENSSL */