1 /* $OpenBSD: kexdhs.c,v 1.26 2018/02/07 02:06:51 jsing 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>
52 static int input_kex_dh_init(int, u_int32_t, struct ssh *);
55 kexdh_server(struct ssh *ssh)
57 struct kex *kex = ssh->kex;
60 /* generate server DH public key */
61 switch (kex->kex_type) {
62 case KEX_DH_GRP1_SHA1:
63 kex->dh = dh_new_group1();
65 case KEX_DH_GRP14_SHA1:
66 case KEX_DH_GRP14_SHA256:
67 kex->dh = dh_new_group14();
69 case KEX_DH_GRP16_SHA512:
70 kex->dh = dh_new_group16();
72 case KEX_DH_GRP18_SHA512:
73 kex->dh = dh_new_group18();
76 r = SSH_ERR_INVALID_ARGUMENT;
79 if (kex->dh == NULL) {
80 r = SSH_ERR_ALLOC_FAIL;
83 if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0)
86 debug("expecting SSH2_MSG_KEXDH_INIT");
87 ssh_dispatch_set(ssh, SSH2_MSG_KEXDH_INIT, &input_kex_dh_init);
94 input_kex_dh_init(int type, u_int32_t seq, struct ssh *ssh)
96 struct kex *kex = ssh->kex;
97 BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
98 struct sshkey *server_host_public, *server_host_private;
99 u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
100 u_char hash[SSH_DIGEST_MAX_LENGTH];
101 size_t sbloblen, slen;
102 size_t klen = 0, hashlen;
105 if (kex->load_host_public_key == NULL ||
106 kex->load_host_private_key == NULL) {
107 r = SSH_ERR_INVALID_ARGUMENT;
110 server_host_public = kex->load_host_public_key(kex->hostkey_type,
111 kex->hostkey_nid, ssh);
112 server_host_private = kex->load_host_private_key(kex->hostkey_type,
113 kex->hostkey_nid, ssh);
114 if (server_host_public == NULL) {
115 r = SSH_ERR_NO_HOSTKEY_LOADED;
120 if ((dh_client_pub = BN_new()) == NULL) {
121 r = SSH_ERR_ALLOC_FAIL;
124 if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 ||
125 (r = sshpkt_get_end(ssh)) != 0)
129 fprintf(stderr, "dh_client_pub= ");
130 BN_print_fp(stderr, dh_client_pub);
131 fprintf(stderr, "\n");
132 debug("bits %d", BN_num_bits(dh_client_pub));
136 DHparams_print_fp(stderr, kex->dh);
137 fprintf(stderr, "pub= ");
138 BN_print_fp(stderr, kex->dh->pub_key);
139 fprintf(stderr, "\n");
141 if (!dh_pub_is_valid(kex->dh, dh_client_pub)) {
142 sshpkt_disconnect(ssh, "bad client public DH value");
143 r = SSH_ERR_MESSAGE_INCOMPLETE;
147 klen = DH_size(kex->dh);
148 if ((kbuf = malloc(klen)) == NULL ||
149 (shared_secret = BN_new()) == NULL) {
150 r = SSH_ERR_ALLOC_FAIL;
153 if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 ||
154 BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
155 r = SSH_ERR_LIBCRYPTO_ERROR;
159 dump_digest("shared secret", kbuf, kout);
161 if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
165 hashlen = sizeof(hash);
166 if ((r = kex_dh_hash(
168 kex->client_version_string,
169 kex->server_version_string,
170 sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
171 sshbuf_ptr(kex->my), sshbuf_len(kex->my),
172 server_host_key_blob, sbloblen,
176 hash, &hashlen)) != 0)
179 /* save session id := H */
180 if (kex->session_id == NULL) {
181 kex->session_id_len = hashlen;
182 kex->session_id = malloc(kex->session_id_len);
183 if (kex->session_id == NULL) {
184 r = SSH_ERR_ALLOC_FAIL;
187 memcpy(kex->session_id, hash, kex->session_id_len);
191 if ((r = kex->sign(server_host_private, server_host_public, &signature,
192 &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0)
195 /* destroy_sensitive_data(); */
197 /* send server hostkey, DH pubkey 'f' and singed H */
198 if ((r = sshpkt_start(ssh, SSH2_MSG_KEXDH_REPLY)) != 0 ||
199 (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
200 (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 || /* f */
201 (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
202 (r = sshpkt_send(ssh)) != 0)
205 if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
206 r = kex_send_newkeys(ssh);
208 explicit_bzero(hash, sizeof(hash));
211 BN_clear_free(dh_client_pub);
213 explicit_bzero(kbuf, klen);
216 BN_clear_free(shared_secret);
217 free(server_host_key_blob);
221 #endif /* WITH_OPENSSL */