1 /* $OpenBSD: kexdhs.c,v 1.14 2013/07/19 07:37:48 markus 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.
28 #include <sys/types.h>
34 #include <openssl/dh.h>
48 #include "monitor_wrap.h"
51 kexdh_server(Kex *kex)
53 BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
55 Key *server_host_public, *server_host_private;
56 u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
57 u_int sbloblen, klen, hashlen, slen;
60 /* generate server DH public key */
61 switch (kex->kex_type) {
62 case KEX_DH_GRP1_SHA1:
65 case KEX_DH_GRP14_SHA1:
66 dh = dh_new_group14();
69 fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
71 dh_gen_key(dh, kex->we_need * 8);
73 debug("expecting SSH2_MSG_KEXDH_INIT");
74 packet_read_expect(SSH2_MSG_KEXDH_INIT);
76 if (kex->load_host_public_key == NULL ||
77 kex->load_host_private_key == NULL)
78 fatal("Cannot load hostkey");
79 server_host_public = kex->load_host_public_key(kex->hostkey_type);
80 if (server_host_public == NULL)
81 fatal("Unsupported hostkey type %d", kex->hostkey_type);
82 server_host_private = kex->load_host_private_key(kex->hostkey_type);
85 if ((dh_client_pub = BN_new()) == NULL)
86 fatal("dh_client_pub == NULL");
87 packet_get_bignum2(dh_client_pub);
91 fprintf(stderr, "dh_client_pub= ");
92 BN_print_fp(stderr, dh_client_pub);
93 fprintf(stderr, "\n");
94 debug("bits %d", BN_num_bits(dh_client_pub));
98 DHparams_print_fp(stderr, dh);
99 fprintf(stderr, "pub= ");
100 BN_print_fp(stderr, dh->pub_key);
101 fprintf(stderr, "\n");
103 if (!dh_pub_is_valid(dh, dh_client_pub))
104 packet_disconnect("bad client public DH value");
107 kbuf = xmalloc(klen);
108 if ((kout = DH_compute_key(kbuf, dh_client_pub, dh)) < 0)
109 fatal("DH_compute_key: failed");
111 dump_digest("shared secret", kbuf, kout);
113 if ((shared_secret = BN_new()) == NULL)
114 fatal("kexdh_server: BN_new failed");
115 if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
116 fatal("kexdh_server: BN_bin2bn failed");
117 memset(kbuf, 0, klen);
120 key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
124 kex->client_version_string,
125 kex->server_version_string,
126 buffer_ptr(&kex->peer), buffer_len(&kex->peer),
127 buffer_ptr(&kex->my), buffer_len(&kex->my),
128 server_host_key_blob, sbloblen,
134 BN_clear_free(dh_client_pub);
136 /* save session id := H */
137 if (kex->session_id == NULL) {
138 kex->session_id_len = hashlen;
139 kex->session_id = xmalloc(kex->session_id_len);
140 memcpy(kex->session_id, hash, kex->session_id_len);
144 kex->sign(server_host_private, server_host_public, &signature, &slen,
147 /* destroy_sensitive_data(); */
149 /* send server hostkey, DH pubkey 'f' and singed H */
150 packet_start(SSH2_MSG_KEXDH_REPLY);
151 packet_put_string(server_host_key_blob, sbloblen);
152 packet_put_bignum2(dh->pub_key); /* f */
153 packet_put_string(signature, slen);
157 free(server_host_key_blob);
158 /* have keys, free DH */
161 kex_derive_keys(kex, hash, hashlen, shared_secret);
162 BN_clear_free(shared_secret);