]>
Commit | Line | Data |
---|---|---|
c20db291 | 1 | /* |
2 | * Copyright (c) 2001 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
08822d99 | 26 | RCSID("$OpenBSD: kexdhs.c,v 1.3 2005/11/04 05:15:59 djm Exp $"); |
c20db291 | 27 | |
28 | #include "xmalloc.h" | |
29 | #include "key.h" | |
30 | #include "kex.h" | |
31 | #include "log.h" | |
32 | #include "packet.h" | |
33 | #include "dh.h" | |
34 | #include "ssh2.h" | |
35 | #include "monitor_wrap.h" | |
36 | ||
37 | void | |
38 | kexdh_server(Kex *kex) | |
39 | { | |
40 | BIGNUM *shared_secret = NULL, *dh_client_pub = NULL; | |
41 | DH *dh; | |
42 | Key *server_host_key; | |
43 | u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL; | |
08822d99 | 44 | u_int sbloblen, klen, kout, hashlen; |
c20db291 | 45 | u_int slen; |
46 | ||
47 | /* generate server DH public key */ | |
7e82606e | 48 | switch (kex->kex_type) { |
49 | case KEX_DH_GRP1_SHA1: | |
50 | dh = dh_new_group1(); | |
51 | break; | |
52 | case KEX_DH_GRP14_SHA1: | |
53 | dh = dh_new_group14(); | |
54 | break; | |
55 | default: | |
56 | fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type); | |
57 | } | |
c20db291 | 58 | dh_gen_key(dh, kex->we_need * 8); |
59 | ||
60 | debug("expecting SSH2_MSG_KEXDH_INIT"); | |
61 | packet_read_expect(SSH2_MSG_KEXDH_INIT); | |
62 | ||
63 | if (kex->load_host_key == NULL) | |
64 | fatal("Cannot load hostkey"); | |
65 | server_host_key = kex->load_host_key(kex->hostkey_type); | |
66 | if (server_host_key == NULL) | |
67 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
68 | ||
69 | /* key, cert */ | |
70 | if ((dh_client_pub = BN_new()) == NULL) | |
71 | fatal("dh_client_pub == NULL"); | |
72 | packet_get_bignum2(dh_client_pub); | |
73 | packet_check_eom(); | |
74 | ||
75 | #ifdef DEBUG_KEXDH | |
76 | fprintf(stderr, "dh_client_pub= "); | |
77 | BN_print_fp(stderr, dh_client_pub); | |
78 | fprintf(stderr, "\n"); | |
79 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
80 | #endif | |
81 | ||
82 | #ifdef DEBUG_KEXDH | |
83 | DHparams_print_fp(stderr, dh); | |
84 | fprintf(stderr, "pub= "); | |
85 | BN_print_fp(stderr, dh->pub_key); | |
86 | fprintf(stderr, "\n"); | |
87 | #endif | |
88 | if (!dh_pub_is_valid(dh, dh_client_pub)) | |
89 | packet_disconnect("bad client public DH value"); | |
90 | ||
91 | klen = DH_size(dh); | |
92 | kbuf = xmalloc(klen); | |
93 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
94 | #ifdef DEBUG_KEXDH | |
95 | dump_digest("shared secret", kbuf, kout); | |
96 | #endif | |
97 | if ((shared_secret = BN_new()) == NULL) | |
98 | fatal("kexdh_server: BN_new failed"); | |
99 | BN_bin2bn(kbuf, kout, shared_secret); | |
100 | memset(kbuf, 0, klen); | |
101 | xfree(kbuf); | |
102 | ||
103 | key_to_blob(server_host_key, &server_host_key_blob, &sbloblen); | |
104 | ||
105 | /* calc H */ | |
08822d99 | 106 | kex_dh_hash( |
c20db291 | 107 | kex->client_version_string, |
108 | kex->server_version_string, | |
109 | buffer_ptr(&kex->peer), buffer_len(&kex->peer), | |
110 | buffer_ptr(&kex->my), buffer_len(&kex->my), | |
111 | server_host_key_blob, sbloblen, | |
112 | dh_client_pub, | |
113 | dh->pub_key, | |
08822d99 | 114 | shared_secret, |
115 | &hash, &hashlen | |
c20db291 | 116 | ); |
117 | BN_clear_free(dh_client_pub); | |
118 | ||
119 | /* save session id := H */ | |
c20db291 | 120 | if (kex->session_id == NULL) { |
08822d99 | 121 | kex->session_id_len = hashlen; |
c20db291 | 122 | kex->session_id = xmalloc(kex->session_id_len); |
123 | memcpy(kex->session_id, hash, kex->session_id_len); | |
124 | } | |
125 | ||
126 | /* sign H */ | |
08822d99 | 127 | PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, hashlen)); |
c20db291 | 128 | |
129 | /* destroy_sensitive_data(); */ | |
130 | ||
131 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
132 | packet_start(SSH2_MSG_KEXDH_REPLY); | |
133 | packet_put_string(server_host_key_blob, sbloblen); | |
134 | packet_put_bignum2(dh->pub_key); /* f */ | |
135 | packet_put_string(signature, slen); | |
136 | packet_send(); | |
137 | ||
138 | xfree(signature); | |
139 | xfree(server_host_key_blob); | |
140 | /* have keys, free DH */ | |
141 | DH_free(dh); | |
142 | ||
08822d99 | 143 | kex_derive_keys(kex, hash, hashlen, shared_secret); |
c20db291 | 144 | BN_clear_free(shared_secret); |
145 | kex_finish(kex); | |
146 | } |