1 /* $OpenBSD: kexdhc.c,v 1.19 2016/05/02 10:26:04 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>
32 #include <openssl/dh.h>
52 static int input_kex_dh(int, u_int32_t, void *);
55 kexdh_client(struct ssh *ssh)
57 struct kex *kex = ssh->kex;
60 /* generate and send 'e', client 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 debug("sending SSH2_MSG_KEXDH_INIT");
84 if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0 ||
85 (r = sshpkt_start(ssh, SSH2_MSG_KEXDH_INIT)) != 0 ||
86 (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 ||
87 (r = sshpkt_send(ssh)) != 0)
90 DHparams_print_fp(stderr, kex->dh);
91 fprintf(stderr, "pub= ");
92 BN_print_fp(stderr, kex->dh->pub_key);
93 fprintf(stderr, "\n");
95 debug("expecting SSH2_MSG_KEXDH_REPLY");
96 ssh_dispatch_set(ssh, SSH2_MSG_KEXDH_REPLY, &input_kex_dh);
103 input_kex_dh(int type, u_int32_t seq, void *ctxt)
105 struct ssh *ssh = ctxt;
106 struct kex *kex = ssh->kex;
107 BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
108 struct sshkey *server_host_key = NULL;
109 u_char *kbuf = NULL, *server_host_key_blob = NULL, *signature = NULL;
110 u_char hash[SSH_DIGEST_MAX_LENGTH];
111 size_t klen = 0, slen, sbloblen, hashlen;
114 if (kex->verify_host_key == NULL) {
115 r = SSH_ERR_INVALID_ARGUMENT;
119 if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
121 (r = sshkey_from_blob(server_host_key_blob, sbloblen,
122 &server_host_key)) != 0)
124 if (server_host_key->type != kex->hostkey_type ||
125 (kex->hostkey_type == KEY_ECDSA &&
126 server_host_key->ecdsa_nid != kex->hostkey_nid)) {
127 r = SSH_ERR_KEY_TYPE_MISMATCH;
130 if (kex->verify_host_key(server_host_key, ssh) == -1) {
131 r = SSH_ERR_SIGNATURE_INVALID;
134 /* DH parameter f, server public DH key */
135 if ((dh_server_pub = BN_new()) == NULL) {
136 r = SSH_ERR_ALLOC_FAIL;
140 if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
141 (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
142 (r = sshpkt_get_end(ssh)) != 0)
145 fprintf(stderr, "dh_server_pub= ");
146 BN_print_fp(stderr, dh_server_pub);
147 fprintf(stderr, "\n");
148 debug("bits %d", BN_num_bits(dh_server_pub));
150 if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
151 sshpkt_disconnect(ssh, "bad server public DH value");
152 r = SSH_ERR_MESSAGE_INCOMPLETE;
156 klen = DH_size(kex->dh);
157 if ((kbuf = malloc(klen)) == NULL ||
158 (shared_secret = BN_new()) == NULL) {
159 r = SSH_ERR_ALLOC_FAIL;
162 if ((kout = DH_compute_key(kbuf, dh_server_pub, kex->dh)) < 0 ||
163 BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
164 r = SSH_ERR_LIBCRYPTO_ERROR;
168 dump_digest("shared secret", kbuf, kout);
171 /* calc and verify H */
172 hashlen = sizeof(hash);
173 if ((r = kex_dh_hash(
175 kex->client_version_string,
176 kex->server_version_string,
177 sshbuf_ptr(kex->my), sshbuf_len(kex->my),
178 sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
179 server_host_key_blob, sbloblen,
183 hash, &hashlen)) != 0)
186 if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen,
190 /* save session id */
191 if (kex->session_id == NULL) {
192 kex->session_id_len = hashlen;
193 kex->session_id = malloc(kex->session_id_len);
194 if (kex->session_id == NULL) {
195 r = SSH_ERR_ALLOC_FAIL;
198 memcpy(kex->session_id, hash, kex->session_id_len);
201 if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
202 r = kex_send_newkeys(ssh);
204 explicit_bzero(hash, sizeof(hash));
208 BN_clear_free(dh_server_pub);
210 explicit_bzero(kbuf, klen);
214 BN_clear_free(shared_secret);
215 sshkey_free(server_host_key);
216 free(server_host_key_blob);
220 #endif /* WITH_OPENSSL */