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 */