diff options
author | Ben Lindstrom <mouring@eviladmin.org> | 2001-04-04 17:39:19 +0000 |
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committer | Ben Lindstrom <mouring@eviladmin.org> | 2001-04-04 17:39:19 +0000 |
commit | 22b19b43e420c9fc711a38631187820573d0f047 (patch) | |
tree | bad6afe1968acc7927423325902efd1054f1b4e0 /kexdh.c | |
parent | f28f634a3ab81669c21fb078565c84410653b8b7 (diff) |
- (bal) Oops.. Missed including kexdh.c and kexgex.c in OpenBSD sync.
Diffstat (limited to 'kexdh.c')
-rw-r--r-- | kexdh.c | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/kexdh.c b/kexdh.c new file mode 100644 index 000000000..8449ec06a --- /dev/null +++ b/kexdh.c | |||
@@ -0,0 +1,304 @@ | |||
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" | ||
26 | RCSID("$OpenBSD: kexdh.c,v 1.2 2001/04/03 23:32:12 markus Exp $"); | ||
27 | |||
28 | #include <openssl/crypto.h> | ||
29 | #include <openssl/bn.h> | ||
30 | |||
31 | #include "xmalloc.h" | ||
32 | #include "buffer.h" | ||
33 | #include "bufaux.h" | ||
34 | #include "key.h" | ||
35 | #include "kex.h" | ||
36 | #include "log.h" | ||
37 | #include "packet.h" | ||
38 | #include "dh.h" | ||
39 | #include "ssh2.h" | ||
40 | |||
41 | u_char * | ||
42 | kex_dh_hash( | ||
43 | char *client_version_string, | ||
44 | char *server_version_string, | ||
45 | char *ckexinit, int ckexinitlen, | ||
46 | char *skexinit, int skexinitlen, | ||
47 | char *serverhostkeyblob, int sbloblen, | ||
48 | BIGNUM *client_dh_pub, | ||
49 | BIGNUM *server_dh_pub, | ||
50 | BIGNUM *shared_secret) | ||
51 | { | ||
52 | Buffer b; | ||
53 | static u_char digest[EVP_MAX_MD_SIZE]; | ||
54 | EVP_MD *evp_md = EVP_sha1(); | ||
55 | EVP_MD_CTX md; | ||
56 | |||
57 | buffer_init(&b); | ||
58 | buffer_put_string(&b, client_version_string, strlen(client_version_string)); | ||
59 | buffer_put_string(&b, server_version_string, strlen(server_version_string)); | ||
60 | |||
61 | /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ | ||
62 | buffer_put_int(&b, ckexinitlen+1); | ||
63 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | ||
64 | buffer_append(&b, ckexinit, ckexinitlen); | ||
65 | buffer_put_int(&b, skexinitlen+1); | ||
66 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | ||
67 | buffer_append(&b, skexinit, skexinitlen); | ||
68 | |||
69 | buffer_put_string(&b, serverhostkeyblob, sbloblen); | ||
70 | buffer_put_bignum2(&b, client_dh_pub); | ||
71 | buffer_put_bignum2(&b, server_dh_pub); | ||
72 | buffer_put_bignum2(&b, shared_secret); | ||
73 | |||
74 | #ifdef DEBUG_KEX | ||
75 | buffer_dump(&b); | ||
76 | #endif | ||
77 | EVP_DigestInit(&md, evp_md); | ||
78 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | ||
79 | EVP_DigestFinal(&md, digest, NULL); | ||
80 | |||
81 | buffer_free(&b); | ||
82 | |||
83 | #ifdef DEBUG_KEX | ||
84 | dump_digest("hash", digest, evp_md->md_size); | ||
85 | #endif | ||
86 | return digest; | ||
87 | } | ||
88 | |||
89 | /* client */ | ||
90 | |||
91 | void | ||
92 | kexdh_client(Kex *kex) | ||
93 | { | ||
94 | BIGNUM *dh_server_pub = NULL, *shared_secret = NULL; | ||
95 | DH *dh; | ||
96 | Key *server_host_key; | ||
97 | char *server_host_key_blob = NULL, *signature = NULL; | ||
98 | u_char *kbuf, *hash; | ||
99 | u_int klen, kout, slen, sbloblen; | ||
100 | int dlen, plen; | ||
101 | |||
102 | /* generate and send 'e', client DH public key */ | ||
103 | dh = dh_new_group1(); | ||
104 | dh_gen_key(dh, kex->we_need * 8); | ||
105 | packet_start(SSH2_MSG_KEXDH_INIT); | ||
106 | packet_put_bignum2(dh->pub_key); | ||
107 | packet_send(); | ||
108 | |||
109 | debug("sending SSH2_MSG_KEXDH_INIT"); | ||
110 | #ifdef DEBUG_KEXDH | ||
111 | DHparams_print_fp(stderr, dh); | ||
112 | fprintf(stderr, "pub= "); | ||
113 | BN_print_fp(stderr, dh->pub_key); | ||
114 | fprintf(stderr, "\n"); | ||
115 | #endif | ||
116 | |||
117 | debug("expecting SSH2_MSG_KEXDH_REPLY"); | ||
118 | packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY); | ||
119 | |||
120 | /* key, cert */ | ||
121 | server_host_key_blob = packet_get_string(&sbloblen); | ||
122 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); | ||
123 | if (server_host_key == NULL) | ||
124 | fatal("cannot decode server_host_key_blob"); | ||
125 | |||
126 | if (kex->check_host_key == NULL) | ||
127 | fatal("cannot check server_host_key"); | ||
128 | kex->check_host_key(server_host_key); | ||
129 | |||
130 | /* DH paramter f, server public DH key */ | ||
131 | dh_server_pub = BN_new(); | ||
132 | if (dh_server_pub == NULL) | ||
133 | fatal("dh_server_pub == NULL"); | ||
134 | packet_get_bignum2(dh_server_pub, &dlen); | ||
135 | |||
136 | #ifdef DEBUG_KEXDH | ||
137 | fprintf(stderr, "dh_server_pub= "); | ||
138 | BN_print_fp(stderr, dh_server_pub); | ||
139 | fprintf(stderr, "\n"); | ||
140 | debug("bits %d", BN_num_bits(dh_server_pub)); | ||
141 | #endif | ||
142 | |||
143 | /* signed H */ | ||
144 | signature = packet_get_string(&slen); | ||
145 | packet_done(); | ||
146 | |||
147 | if (!dh_pub_is_valid(dh, dh_server_pub)) | ||
148 | packet_disconnect("bad server public DH value"); | ||
149 | |||
150 | klen = DH_size(dh); | ||
151 | kbuf = xmalloc(klen); | ||
152 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | ||
153 | #ifdef DEBUG_KEXDH | ||
154 | dump_digest("shared secret", kbuf, kout); | ||
155 | #endif | ||
156 | shared_secret = BN_new(); | ||
157 | BN_bin2bn(kbuf, kout, shared_secret); | ||
158 | memset(kbuf, 0, klen); | ||
159 | xfree(kbuf); | ||
160 | |||
161 | /* calc and verify H */ | ||
162 | hash = kex_dh_hash( | ||
163 | kex->client_version_string, | ||
164 | kex->server_version_string, | ||
165 | buffer_ptr(&kex->my), buffer_len(&kex->my), | ||
166 | buffer_ptr(&kex->peer), buffer_len(&kex->peer), | ||
167 | server_host_key_blob, sbloblen, | ||
168 | dh->pub_key, | ||
169 | dh_server_pub, | ||
170 | shared_secret | ||
171 | ); | ||
172 | xfree(server_host_key_blob); | ||
173 | DH_free(dh); | ||
174 | BN_free(dh_server_pub); | ||
175 | |||
176 | if (key_verify(server_host_key, (u_char *)signature, slen, hash, 20) != 1) | ||
177 | fatal("key_verify failed for server_host_key"); | ||
178 | key_free(server_host_key); | ||
179 | xfree(signature); | ||
180 | |||
181 | /* save session id */ | ||
182 | if (kex->session_id == NULL) { | ||
183 | kex->session_id_len = 20; | ||
184 | kex->session_id = xmalloc(kex->session_id_len); | ||
185 | memcpy(kex->session_id, hash, kex->session_id_len); | ||
186 | } | ||
187 | |||
188 | kex_derive_keys(kex, hash, shared_secret); | ||
189 | BN_clear_free(shared_secret); | ||
190 | kex_send_newkeys(); | ||
191 | } | ||
192 | |||
193 | /* server */ | ||
194 | |||
195 | void | ||
196 | kexdh_server(Kex *kex) | ||
197 | { | ||
198 | BIGNUM *shared_secret = NULL, *dh_client_pub = NULL; | ||
199 | DH *dh; | ||
200 | Key *server_host_key; | ||
201 | u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL; | ||
202 | u_int sbloblen, klen, kout; | ||
203 | int dlen, slen, plen; | ||
204 | |||
205 | /* generate server DH public key */ | ||
206 | dh = dh_new_group1(); | ||
207 | dh_gen_key(dh, kex->we_need * 8); | ||
208 | |||
209 | debug("expecting SSH2_MSG_KEXDH_INIT"); | ||
210 | packet_read_expect(&plen, SSH2_MSG_KEXDH_INIT); | ||
211 | |||
212 | if (kex->load_host_key == NULL) | ||
213 | fatal("Cannot load hostkey"); | ||
214 | server_host_key = kex->load_host_key(kex->hostkey_type); | ||
215 | if (server_host_key == NULL) | ||
216 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | ||
217 | |||
218 | /* key, cert */ | ||
219 | dh_client_pub = BN_new(); | ||
220 | if (dh_client_pub == NULL) | ||
221 | fatal("dh_client_pub == NULL"); | ||
222 | packet_get_bignum2(dh_client_pub, &dlen); | ||
223 | |||
224 | #ifdef DEBUG_KEXDH | ||
225 | fprintf(stderr, "dh_client_pub= "); | ||
226 | BN_print_fp(stderr, dh_client_pub); | ||
227 | fprintf(stderr, "\n"); | ||
228 | debug("bits %d", BN_num_bits(dh_client_pub)); | ||
229 | #endif | ||
230 | |||
231 | #ifdef DEBUG_KEXDH | ||
232 | DHparams_print_fp(stderr, dh); | ||
233 | fprintf(stderr, "pub= "); | ||
234 | BN_print_fp(stderr, dh->pub_key); | ||
235 | fprintf(stderr, "\n"); | ||
236 | #endif | ||
237 | if (!dh_pub_is_valid(dh, dh_client_pub)) | ||
238 | packet_disconnect("bad client public DH value"); | ||
239 | |||
240 | klen = DH_size(dh); | ||
241 | kbuf = xmalloc(klen); | ||
242 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | ||
243 | #ifdef DEBUG_KEXDH | ||
244 | dump_digest("shared secret", kbuf, kout); | ||
245 | #endif | ||
246 | shared_secret = BN_new(); | ||
247 | BN_bin2bn(kbuf, kout, shared_secret); | ||
248 | memset(kbuf, 0, klen); | ||
249 | xfree(kbuf); | ||
250 | |||
251 | key_to_blob(server_host_key, &server_host_key_blob, &sbloblen); | ||
252 | |||
253 | /* calc H */ | ||
254 | hash = kex_dh_hash( | ||
255 | kex->client_version_string, | ||
256 | kex->server_version_string, | ||
257 | buffer_ptr(&kex->peer), buffer_len(&kex->peer), | ||
258 | buffer_ptr(&kex->my), buffer_len(&kex->my), | ||
259 | (char *)server_host_key_blob, sbloblen, | ||
260 | dh_client_pub, | ||
261 | dh->pub_key, | ||
262 | shared_secret | ||
263 | ); | ||
264 | BN_free(dh_client_pub); | ||
265 | |||
266 | /* save session id := H */ | ||
267 | /* XXX hashlen depends on KEX */ | ||
268 | if (kex->session_id == NULL) { | ||
269 | kex->session_id_len = 20; | ||
270 | kex->session_id = xmalloc(kex->session_id_len); | ||
271 | memcpy(kex->session_id, hash, kex->session_id_len); | ||
272 | } | ||
273 | |||
274 | /* sign H */ | ||
275 | /* XXX hashlen depends on KEX */ | ||
276 | key_sign(server_host_key, &signature, &slen, hash, 20); | ||
277 | |||
278 | /* destroy_sensitive_data(); */ | ||
279 | |||
280 | /* send server hostkey, DH pubkey 'f' and singed H */ | ||
281 | packet_start(SSH2_MSG_KEXDH_REPLY); | ||
282 | packet_put_string((char *)server_host_key_blob, sbloblen); | ||
283 | packet_put_bignum2(dh->pub_key); /* f */ | ||
284 | packet_put_string((char *)signature, slen); | ||
285 | packet_send(); | ||
286 | xfree(signature); | ||
287 | xfree(server_host_key_blob); | ||
288 | |||
289 | kex_derive_keys(kex, hash, shared_secret); | ||
290 | BN_clear_free(shared_secret); | ||
291 | kex_send_newkeys(); | ||
292 | |||
293 | /* have keys, free DH */ | ||
294 | DH_free(dh); | ||
295 | } | ||
296 | |||
297 | void | ||
298 | kexdh(Kex *kex) | ||
299 | { | ||
300 | if (kex->server) | ||
301 | kexdh_server(kex); | ||
302 | else | ||
303 | kexdh_client(kex); | ||
304 | } | ||