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1 | /* $OpenBSD: kex.c,v 1.79 2007/06/05 06:52:37 djm Exp $ */ | |
2 | /* | |
3 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
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. | |
13 | * | |
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. | |
24 | */ | |
25 | ||
26 | #include "includes.h" | |
27 | ||
28 | #include <sys/param.h> | |
29 | ||
30 | #include <signal.h> | |
31 | #include <stdarg.h> | |
32 | #include <stdio.h> | |
33 | #include <stdlib.h> | |
34 | #include <string.h> | |
35 | ||
36 | #include <openssl/crypto.h> | |
37 | ||
38 | #include "xmalloc.h" | |
39 | #include "ssh2.h" | |
40 | #include "buffer.h" | |
41 | #include "packet.h" | |
42 | #include "compat.h" | |
43 | #include "cipher.h" | |
44 | #include "key.h" | |
45 | #include "kex.h" | |
46 | #include "log.h" | |
47 | #include "mac.h" | |
48 | #include "match.h" | |
49 | #include "dispatch.h" | |
50 | #include "monitor.h" | |
51 | ||
52 | #ifdef GSSAPI | |
53 | #include "ssh-gss.h" | |
54 | #endif | |
55 | ||
56 | #define KEX_COOKIE_LEN 16 | |
57 | ||
58 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L | |
59 | # if defined(HAVE_EVP_SHA256) | |
60 | # define evp_ssh_sha256 EVP_sha256 | |
61 | # else | |
62 | extern const EVP_MD *evp_ssh_sha256(void); | |
63 | # endif | |
64 | #endif | |
65 | ||
66 | /* prototype */ | |
67 | static void kex_kexinit_finish(Kex *); | |
68 | static void kex_choose_conf(Kex *); | |
69 | ||
70 | /* put algorithm proposal into buffer */ | |
71 | void | |
72 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) | |
73 | { | |
74 | u_int i; | |
75 | ||
76 | buffer_clear(b); | |
77 | /* | |
78 | * add a dummy cookie, the cookie will be overwritten by | |
79 | * kex_send_kexinit(), each time a kexinit is set | |
80 | */ | |
81 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
82 | buffer_put_char(b, 0); | |
83 | for (i = 0; i < PROPOSAL_MAX; i++) | |
84 | buffer_put_cstring(b, proposal[i]); | |
85 | buffer_put_char(b, 0); /* first_kex_packet_follows */ | |
86 | buffer_put_int(b, 0); /* uint32 reserved */ | |
87 | } | |
88 | ||
89 | /* parse buffer and return algorithm proposal */ | |
90 | static char ** | |
91 | kex_buf2prop(Buffer *raw, int *first_kex_follows) | |
92 | { | |
93 | Buffer b; | |
94 | u_int i; | |
95 | char **proposal; | |
96 | ||
97 | proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); | |
98 | ||
99 | buffer_init(&b); | |
100 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); | |
101 | /* skip cookie */ | |
102 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
103 | buffer_get_char(&b); | |
104 | /* extract kex init proposal strings */ | |
105 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
106 | proposal[i] = buffer_get_string(&b,NULL); | |
107 | debug2("kex_parse_kexinit: %s", proposal[i]); | |
108 | } | |
109 | /* first kex follows / reserved */ | |
110 | i = buffer_get_char(&b); | |
111 | if (first_kex_follows != NULL) | |
112 | *first_kex_follows = i; | |
113 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); | |
114 | i = buffer_get_int(&b); | |
115 | debug2("kex_parse_kexinit: reserved %u ", i); | |
116 | buffer_free(&b); | |
117 | return proposal; | |
118 | } | |
119 | ||
120 | static void | |
121 | kex_prop_free(char **proposal) | |
122 | { | |
123 | u_int i; | |
124 | ||
125 | for (i = 0; i < PROPOSAL_MAX; i++) | |
126 | xfree(proposal[i]); | |
127 | xfree(proposal); | |
128 | } | |
129 | ||
130 | /* ARGSUSED */ | |
131 | static void | |
132 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) | |
133 | { | |
134 | error("Hm, kex protocol error: type %d seq %u", type, seq); | |
135 | } | |
136 | ||
137 | static void | |
138 | kex_reset_dispatch(void) | |
139 | { | |
140 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, | |
141 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); | |
142 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); | |
143 | } | |
144 | ||
145 | void | |
146 | kex_finish(Kex *kex) | |
147 | { | |
148 | kex_reset_dispatch(); | |
149 | ||
150 | packet_start(SSH2_MSG_NEWKEYS); | |
151 | packet_send(); | |
152 | /* packet_write_wait(); */ | |
153 | debug("SSH2_MSG_NEWKEYS sent"); | |
154 | ||
155 | debug("expecting SSH2_MSG_NEWKEYS"); | |
156 | packet_read_expect(SSH2_MSG_NEWKEYS); | |
157 | packet_check_eom(); | |
158 | debug("SSH2_MSG_NEWKEYS received"); | |
159 | ||
160 | kex->done = 1; | |
161 | buffer_clear(&kex->peer); | |
162 | /* buffer_clear(&kex->my); */ | |
163 | kex->flags &= ~KEX_INIT_SENT; | |
164 | xfree(kex->name); | |
165 | kex->name = NULL; | |
166 | } | |
167 | ||
168 | void | |
169 | kex_send_kexinit(Kex *kex) | |
170 | { | |
171 | u_int32_t rnd = 0; | |
172 | u_char *cookie; | |
173 | u_int i; | |
174 | ||
175 | if (kex == NULL) { | |
176 | error("kex_send_kexinit: no kex, cannot rekey"); | |
177 | return; | |
178 | } | |
179 | if (kex->flags & KEX_INIT_SENT) { | |
180 | debug("KEX_INIT_SENT"); | |
181 | return; | |
182 | } | |
183 | kex->done = 0; | |
184 | ||
185 | /* generate a random cookie */ | |
186 | if (buffer_len(&kex->my) < KEX_COOKIE_LEN) | |
187 | fatal("kex_send_kexinit: kex proposal too short"); | |
188 | cookie = buffer_ptr(&kex->my); | |
189 | for (i = 0; i < KEX_COOKIE_LEN; i++) { | |
190 | if (i % 4 == 0) | |
191 | rnd = arc4random(); | |
192 | cookie[i] = rnd; | |
193 | rnd >>= 8; | |
194 | } | |
195 | packet_start(SSH2_MSG_KEXINIT); | |
196 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); | |
197 | packet_send(); | |
198 | debug("SSH2_MSG_KEXINIT sent"); | |
199 | kex->flags |= KEX_INIT_SENT; | |
200 | } | |
201 | ||
202 | /* ARGSUSED */ | |
203 | void | |
204 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) | |
205 | { | |
206 | char *ptr; | |
207 | u_int i, dlen; | |
208 | Kex *kex = (Kex *)ctxt; | |
209 | ||
210 | debug("SSH2_MSG_KEXINIT received"); | |
211 | if (kex == NULL) | |
212 | fatal("kex_input_kexinit: no kex, cannot rekey"); | |
213 | ||
214 | ptr = packet_get_raw(&dlen); | |
215 | buffer_append(&kex->peer, ptr, dlen); | |
216 | ||
217 | /* discard packet */ | |
218 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
219 | packet_get_char(); | |
220 | for (i = 0; i < PROPOSAL_MAX; i++) | |
221 | xfree(packet_get_string(NULL)); | |
222 | (void) packet_get_char(); | |
223 | (void) packet_get_int(); | |
224 | packet_check_eom(); | |
225 | ||
226 | kex_kexinit_finish(kex); | |
227 | } | |
228 | ||
229 | Kex * | |
230 | kex_setup(char *proposal[PROPOSAL_MAX]) | |
231 | { | |
232 | Kex *kex; | |
233 | ||
234 | kex = xcalloc(1, sizeof(*kex)); | |
235 | buffer_init(&kex->peer); | |
236 | buffer_init(&kex->my); | |
237 | kex_prop2buf(&kex->my, proposal); | |
238 | kex->done = 0; | |
239 | ||
240 | kex_send_kexinit(kex); /* we start */ | |
241 | kex_reset_dispatch(); | |
242 | ||
243 | return kex; | |
244 | } | |
245 | ||
246 | static void | |
247 | kex_kexinit_finish(Kex *kex) | |
248 | { | |
249 | if (!(kex->flags & KEX_INIT_SENT)) | |
250 | kex_send_kexinit(kex); | |
251 | ||
252 | kex_choose_conf(kex); | |
253 | ||
254 | if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && | |
255 | kex->kex[kex->kex_type] != NULL) { | |
256 | (kex->kex[kex->kex_type])(kex); | |
257 | } else { | |
258 | fatal("Unsupported key exchange %d", kex->kex_type); | |
259 | } | |
260 | } | |
261 | ||
262 | static void | |
263 | choose_enc(Enc *enc, char *client, char *server) | |
264 | { | |
265 | char *name = match_list(client, server, NULL); | |
266 | if (name == NULL) | |
267 | fatal("no matching cipher found: client %s server %s", | |
268 | client, server); | |
269 | if ((enc->cipher = cipher_by_name(name)) == NULL) | |
270 | fatal("matching cipher is not supported: %s", name); | |
271 | enc->name = name; | |
272 | enc->enabled = 0; | |
273 | enc->iv = NULL; | |
274 | enc->key = NULL; | |
275 | enc->key_len = cipher_keylen(enc->cipher); | |
276 | enc->block_size = cipher_blocksize(enc->cipher); | |
277 | } | |
278 | ||
279 | static void | |
280 | choose_mac(Mac *mac, char *client, char *server) | |
281 | { | |
282 | char *name = match_list(client, server, NULL); | |
283 | if (name == NULL) | |
284 | fatal("no matching mac found: client %s server %s", | |
285 | client, server); | |
286 | if (mac_setup(mac, name) < 0) | |
287 | fatal("unsupported mac %s", name); | |
288 | /* truncate the key */ | |
289 | if (datafellows & SSH_BUG_HMAC) | |
290 | mac->key_len = 16; | |
291 | mac->name = name; | |
292 | mac->key = NULL; | |
293 | mac->enabled = 0; | |
294 | } | |
295 | ||
296 | static void | |
297 | choose_comp(Comp *comp, char *client, char *server) | |
298 | { | |
299 | char *name = match_list(client, server, NULL); | |
300 | if (name == NULL) | |
301 | fatal("no matching comp found: client %s server %s", client, server); | |
302 | if (strcmp(name, "zlib@openssh.com") == 0) { | |
303 | comp->type = COMP_DELAYED; | |
304 | } else if (strcmp(name, "zlib") == 0) { | |
305 | comp->type = COMP_ZLIB; | |
306 | } else if (strcmp(name, "none") == 0) { | |
307 | comp->type = COMP_NONE; | |
308 | } else { | |
309 | fatal("unsupported comp %s", name); | |
310 | } | |
311 | comp->name = name; | |
312 | } | |
313 | ||
314 | static void | |
315 | choose_kex(Kex *k, char *client, char *server) | |
316 | { | |
317 | k->name = match_list(client, server, NULL); | |
318 | if (k->name == NULL) | |
319 | fatal("Unable to negotiate a key exchange method"); | |
320 | if (strcmp(k->name, KEX_DH1) == 0) { | |
321 | k->kex_type = KEX_DH_GRP1_SHA1; | |
322 | k->evp_md = EVP_sha1(); | |
323 | } else if (strcmp(k->name, KEX_DH14) == 0) { | |
324 | k->kex_type = KEX_DH_GRP14_SHA1; | |
325 | k->evp_md = EVP_sha1(); | |
326 | } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { | |
327 | k->kex_type = KEX_DH_GEX_SHA1; | |
328 | k->evp_md = EVP_sha1(); | |
329 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L | |
330 | } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { | |
331 | k->kex_type = KEX_DH_GEX_SHA256; | |
332 | k->evp_md = evp_ssh_sha256(); | |
333 | #endif | |
334 | #ifdef GSSAPI | |
335 | } else if (strncmp(k->name, KEX_GSS_GEX_SHA1_ID, | |
336 | sizeof(KEX_GSS_GEX_SHA1_ID) - 1) == 0) { | |
337 | k->kex_type = KEX_GSS_GEX_SHA1; | |
338 | k->evp_md = EVP_sha1(); | |
339 | } else if (strncmp(k->name, KEX_GSS_GRP1_SHA1_ID, | |
340 | sizeof(KEX_GSS_GRP1_SHA1_ID) - 1) == 0) { | |
341 | k->kex_type = KEX_GSS_GRP1_SHA1; | |
342 | k->evp_md = EVP_sha1(); | |
343 | } else if (strncmp(k->name, KEX_GSS_GRP14_SHA1_ID, | |
344 | sizeof(KEX_GSS_GRP14_SHA1_ID) - 1) == 0) { | |
345 | k->kex_type = KEX_GSS_GRP14_SHA1; | |
346 | k->evp_md = EVP_sha1(); | |
347 | #endif | |
348 | } else | |
349 | fatal("bad kex alg %s", k->name); | |
350 | } | |
351 | ||
352 | static void | |
353 | choose_hostkeyalg(Kex *k, char *client, char *server) | |
354 | { | |
355 | char *hostkeyalg = match_list(client, server, NULL); | |
356 | if (hostkeyalg == NULL) | |
357 | fatal("no hostkey alg"); | |
358 | k->hostkey_type = key_type_from_name(hostkeyalg); | |
359 | if (k->hostkey_type == KEY_UNSPEC) | |
360 | fatal("bad hostkey alg '%s'", hostkeyalg); | |
361 | xfree(hostkeyalg); | |
362 | } | |
363 | ||
364 | static int | |
365 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) | |
366 | { | |
367 | static int check[] = { | |
368 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 | |
369 | }; | |
370 | int *idx; | |
371 | char *p; | |
372 | ||
373 | for (idx = &check[0]; *idx != -1; idx++) { | |
374 | if ((p = strchr(my[*idx], ',')) != NULL) | |
375 | *p = '\0'; | |
376 | if ((p = strchr(peer[*idx], ',')) != NULL) | |
377 | *p = '\0'; | |
378 | if (strcmp(my[*idx], peer[*idx]) != 0) { | |
379 | debug2("proposal mismatch: my %s peer %s", | |
380 | my[*idx], peer[*idx]); | |
381 | return (0); | |
382 | } | |
383 | } | |
384 | debug2("proposals match"); | |
385 | return (1); | |
386 | } | |
387 | ||
388 | static void | |
389 | kex_choose_conf(Kex *kex) | |
390 | { | |
391 | Newkeys *newkeys; | |
392 | char **my, **peer; | |
393 | char **cprop, **sprop; | |
394 | int nenc, nmac, ncomp; | |
395 | u_int mode, ctos, need; | |
396 | int first_kex_follows, type; | |
397 | ||
398 | my = kex_buf2prop(&kex->my, NULL); | |
399 | peer = kex_buf2prop(&kex->peer, &first_kex_follows); | |
400 | ||
401 | if (kex->server) { | |
402 | cprop=peer; | |
403 | sprop=my; | |
404 | } else { | |
405 | cprop=my; | |
406 | sprop=peer; | |
407 | } | |
408 | ||
409 | /* Algorithm Negotiation */ | |
410 | for (mode = 0; mode < MODE_MAX; mode++) { | |
411 | newkeys = xcalloc(1, sizeof(*newkeys)); | |
412 | kex->newkeys[mode] = newkeys; | |
413 | ctos = (!kex->server && mode == MODE_OUT) || | |
414 | (kex->server && mode == MODE_IN); | |
415 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; | |
416 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; | |
417 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; | |
418 | choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]); | |
419 | choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]); | |
420 | choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); | |
421 | debug("kex: %s %s %s %s", | |
422 | ctos ? "client->server" : "server->client", | |
423 | newkeys->enc.name, | |
424 | newkeys->mac.name, | |
425 | newkeys->comp.name); | |
426 | } | |
427 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); | |
428 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], | |
429 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); | |
430 | need = 0; | |
431 | for (mode = 0; mode < MODE_MAX; mode++) { | |
432 | newkeys = kex->newkeys[mode]; | |
433 | if (need < newkeys->enc.key_len) | |
434 | need = newkeys->enc.key_len; | |
435 | if (need < newkeys->enc.block_size) | |
436 | need = newkeys->enc.block_size; | |
437 | if (need < newkeys->mac.key_len) | |
438 | need = newkeys->mac.key_len; | |
439 | } | |
440 | /* XXX need runden? */ | |
441 | kex->we_need = need; | |
442 | ||
443 | /* ignore the next message if the proposals do not match */ | |
444 | if (first_kex_follows && !proposals_match(my, peer) && | |
445 | !(datafellows & SSH_BUG_FIRSTKEX)) { | |
446 | type = packet_read(); | |
447 | debug2("skipping next packet (type %u)", type); | |
448 | } | |
449 | ||
450 | kex_prop_free(my); | |
451 | kex_prop_free(peer); | |
452 | } | |
453 | ||
454 | static u_char * | |
455 | derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, | |
456 | BIGNUM *shared_secret) | |
457 | { | |
458 | Buffer b; | |
459 | EVP_MD_CTX md; | |
460 | char c = id; | |
461 | u_int have; | |
462 | int mdsz; | |
463 | u_char *digest; | |
464 | ||
465 | if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) | |
466 | fatal("bad kex md size %d", mdsz); | |
467 | digest = xmalloc(roundup(need, mdsz)); | |
468 | ||
469 | buffer_init(&b); | |
470 | buffer_put_bignum2(&b, shared_secret); | |
471 | ||
472 | /* K1 = HASH(K || H || "A" || session_id) */ | |
473 | EVP_DigestInit(&md, kex->evp_md); | |
474 | if (!(datafellows & SSH_BUG_DERIVEKEY)) | |
475 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
476 | EVP_DigestUpdate(&md, hash, hashlen); | |
477 | EVP_DigestUpdate(&md, &c, 1); | |
478 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); | |
479 | EVP_DigestFinal(&md, digest, NULL); | |
480 | ||
481 | /* | |
482 | * expand key: | |
483 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) | |
484 | * Key = K1 || K2 || ... || Kn | |
485 | */ | |
486 | for (have = mdsz; need > have; have += mdsz) { | |
487 | EVP_DigestInit(&md, kex->evp_md); | |
488 | if (!(datafellows & SSH_BUG_DERIVEKEY)) | |
489 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
490 | EVP_DigestUpdate(&md, hash, hashlen); | |
491 | EVP_DigestUpdate(&md, digest, have); | |
492 | EVP_DigestFinal(&md, digest + have, NULL); | |
493 | } | |
494 | buffer_free(&b); | |
495 | #ifdef DEBUG_KEX | |
496 | fprintf(stderr, "key '%c'== ", c); | |
497 | dump_digest("key", digest, need); | |
498 | #endif | |
499 | return digest; | |
500 | } | |
501 | ||
502 | Newkeys *current_keys[MODE_MAX]; | |
503 | ||
504 | #define NKEYS 6 | |
505 | void | |
506 | kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) | |
507 | { | |
508 | u_char *keys[NKEYS]; | |
509 | u_int i, mode, ctos; | |
510 | ||
511 | for (i = 0; i < NKEYS; i++) { | |
512 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, | |
513 | shared_secret); | |
514 | } | |
515 | ||
516 | debug2("kex_derive_keys"); | |
517 | for (mode = 0; mode < MODE_MAX; mode++) { | |
518 | current_keys[mode] = kex->newkeys[mode]; | |
519 | kex->newkeys[mode] = NULL; | |
520 | ctos = (!kex->server && mode == MODE_OUT) || | |
521 | (kex->server && mode == MODE_IN); | |
522 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; | |
523 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; | |
524 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; | |
525 | } | |
526 | } | |
527 | ||
528 | Newkeys * | |
529 | kex_get_newkeys(int mode) | |
530 | { | |
531 | Newkeys *ret; | |
532 | ||
533 | ret = current_keys[mode]; | |
534 | current_keys[mode] = NULL; | |
535 | return ret; | |
536 | } | |
537 | ||
538 | void | |
539 | derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, | |
540 | u_int8_t cookie[8], u_int8_t id[16]) | |
541 | { | |
542 | const EVP_MD *evp_md = EVP_md5(); | |
543 | EVP_MD_CTX md; | |
544 | u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; | |
545 | int len; | |
546 | ||
547 | EVP_DigestInit(&md, evp_md); | |
548 | ||
549 | len = BN_num_bytes(host_modulus); | |
550 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) | |
551 | fatal("%s: bad host modulus (len %d)", __func__, len); | |
552 | BN_bn2bin(host_modulus, nbuf); | |
553 | EVP_DigestUpdate(&md, nbuf, len); | |
554 | ||
555 | len = BN_num_bytes(server_modulus); | |
556 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) | |
557 | fatal("%s: bad server modulus (len %d)", __func__, len); | |
558 | BN_bn2bin(server_modulus, nbuf); | |
559 | EVP_DigestUpdate(&md, nbuf, len); | |
560 | ||
561 | EVP_DigestUpdate(&md, cookie, 8); | |
562 | ||
563 | EVP_DigestFinal(&md, obuf, NULL); | |
564 | memcpy(id, obuf, 16); | |
565 | ||
566 | memset(nbuf, 0, sizeof(nbuf)); | |
567 | memset(obuf, 0, sizeof(obuf)); | |
568 | memset(&md, 0, sizeof(md)); | |
569 | } | |
570 | ||
571 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) | |
572 | void | |
573 | dump_digest(char *msg, u_char *digest, int len) | |
574 | { | |
575 | u_int i; | |
576 | ||
577 | fprintf(stderr, "%s\n", msg); | |
578 | for (i = 0; i < len; i++) { | |
579 | fprintf(stderr, "%02x", digest[i]); | |
580 | if (i%32 == 31) | |
581 | fprintf(stderr, "\n"); | |
582 | else if (i%8 == 7) | |
583 | fprintf(stderr, " "); | |
584 | } | |
585 | fprintf(stderr, "\n"); | |
586 | } | |
587 | #endif |