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4f8c6159 | 1 | /* |
2 | * Copyright (c) 2000 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. | |
4f8c6159 | 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" | |
fa08c86b | 26 | RCSID("$OpenBSD: kex.c,v 1.13 2000/11/12 19:50:37 markus Exp $"); |
4f8c6159 | 27 | |
28 | #include "ssh.h" | |
29 | #include "ssh2.h" | |
30 | #include "xmalloc.h" | |
31 | #include "buffer.h" | |
32 | #include "bufaux.h" | |
71276795 | 33 | #include "packet.h" |
4f8c6159 | 34 | #include "compat.h" |
35 | ||
36 | #include <openssl/bn.h> | |
37 | #include <openssl/dh.h> | |
38 | ||
39 | #include <openssl/crypto.h> | |
40 | #include <openssl/bio.h> | |
41 | #include <openssl/bn.h> | |
42 | #include <openssl/dh.h> | |
43 | #include <openssl/pem.h> | |
44 | ||
45 | #include "kex.h" | |
fa08c86b | 46 | #include "key.h" |
4f8c6159 | 47 | |
71276795 | 48 | #define KEX_COOKIE_LEN 16 |
49 | ||
4f8c6159 | 50 | Buffer * |
51 | kex_init(char *myproposal[PROPOSAL_MAX]) | |
52 | { | |
71276795 | 53 | int first_kex_packet_follows = 0; |
54 | unsigned char cookie[KEX_COOKIE_LEN]; | |
4f8c6159 | 55 | u_int32_t rand = 0; |
56 | int i; | |
57 | Buffer *ki = xmalloc(sizeof(*ki)); | |
71276795 | 58 | for (i = 0; i < KEX_COOKIE_LEN; i++) { |
4f8c6159 | 59 | if (i % 4 == 0) |
60 | rand = arc4random(); | |
61 | cookie[i] = rand & 0xff; | |
62 | rand >>= 8; | |
63 | } | |
64 | buffer_init(ki); | |
65 | buffer_append(ki, (char *)cookie, sizeof cookie); | |
66 | for (i = 0; i < PROPOSAL_MAX; i++) | |
67 | buffer_put_cstring(ki, myproposal[i]); | |
71276795 | 68 | buffer_put_char(ki, first_kex_packet_follows); |
69 | buffer_put_int(ki, 0); /* uint32 reserved */ | |
4f8c6159 | 70 | return ki; |
71 | } | |
72 | ||
71276795 | 73 | /* send kexinit, parse and save reply */ |
74 | void | |
75 | kex_exchange_kexinit( | |
76 | Buffer *my_kexinit, Buffer *peer_kexint, | |
77 | char *peer_proposal[PROPOSAL_MAX]) | |
78 | { | |
79 | int i; | |
80 | char *ptr; | |
81 | int plen; | |
82 | ||
83 | debug("send KEXINIT"); | |
84 | packet_start(SSH2_MSG_KEXINIT); | |
85 | packet_put_raw(buffer_ptr(my_kexinit), buffer_len(my_kexinit)); | |
86 | packet_send(); | |
87 | packet_write_wait(); | |
88 | debug("done"); | |
89 | ||
90 | /* | |
91 | * read and save raw KEXINIT payload in buffer. this is used during | |
92 | * computation of the session_id and the session keys. | |
93 | */ | |
94 | debug("wait KEXINIT"); | |
95 | packet_read_expect(&plen, SSH2_MSG_KEXINIT); | |
96 | ptr = packet_get_raw(&plen); | |
97 | buffer_append(peer_kexint, ptr, plen); | |
98 | ||
99 | /* parse packet and save algorithm proposal */ | |
100 | /* skip cookie */ | |
101 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
102 | packet_get_char(); | |
103 | /* extract kex init proposal strings */ | |
104 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
105 | peer_proposal[i] = packet_get_string(NULL); | |
106 | debug("got kexinit: %s", peer_proposal[i]); | |
107 | } | |
108 | /* first kex follow / reserved */ | |
109 | i = packet_get_char(); | |
110 | debug("first kex follow: %d ", i); | |
111 | i = packet_get_int(); | |
112 | debug("reserved: %d ", i); | |
113 | packet_done(); | |
114 | debug("done"); | |
115 | } | |
116 | ||
4f8c6159 | 117 | /* diffie-hellman-group1-sha1 */ |
118 | ||
119 | int | |
120 | dh_pub_is_valid(DH *dh, BIGNUM *dh_pub) | |
121 | { | |
122 | int i; | |
123 | int n = BN_num_bits(dh_pub); | |
124 | int bits_set = 0; | |
125 | ||
4f8c6159 | 126 | if (dh_pub->neg) { |
127 | log("invalid public DH value: negativ"); | |
128 | return 0; | |
129 | } | |
130 | for (i = 0; i <= n; i++) | |
131 | if (BN_is_bit_set(dh_pub, i)) | |
132 | bits_set++; | |
133 | debug("bits set: %d/%d", bits_set, BN_num_bits(dh->p)); | |
134 | ||
135 | /* if g==2 and bits_set==1 then computing log_g(dh_pub) is trivial */ | |
136 | if (bits_set > 1 && (BN_cmp(dh_pub, dh->p) == -1)) | |
137 | return 1; | |
138 | log("invalid public DH value (%d/%d)", bits_set, BN_num_bits(dh->p)); | |
139 | return 0; | |
140 | } | |
141 | ||
142 | DH * | |
94ec8c6b | 143 | dh_gen_key(DH *dh) |
4f8c6159 | 144 | { |
94ec8c6b | 145 | int tries = 0; |
146 | ||
4f8c6159 | 147 | do { |
148 | if (DH_generate_key(dh) == 0) | |
149 | fatal("DH_generate_key"); | |
150 | if (tries++ > 10) | |
151 | fatal("dh_new_group1: too many bad keys: giving up"); | |
152 | } while (!dh_pub_is_valid(dh, dh->pub_key)); | |
153 | return dh; | |
154 | } | |
155 | ||
94ec8c6b | 156 | DH * |
157 | dh_new_group_asc(const char *gen, const char *modulus) | |
158 | { | |
159 | DH *dh; | |
160 | int ret; | |
161 | ||
162 | dh = DH_new(); | |
163 | if (dh == NULL) | |
164 | fatal("DH_new"); | |
165 | ||
166 | if ((ret = BN_hex2bn(&dh->p, modulus)) < 0) | |
167 | fatal("BN_hex2bn p"); | |
168 | if ((ret = BN_hex2bn(&dh->g, gen)) < 0) | |
169 | fatal("BN_hex2bn g"); | |
170 | ||
171 | return (dh_gen_key(dh)); | |
172 | } | |
173 | ||
174 | DH * | |
175 | dh_new_group(BIGNUM *gen, BIGNUM *modulus) | |
176 | { | |
177 | DH *dh; | |
178 | ||
179 | dh = DH_new(); | |
180 | if (dh == NULL) | |
181 | fatal("DH_new"); | |
182 | dh->p = modulus; | |
183 | dh->g = gen; | |
184 | ||
185 | return (dh_gen_key(dh)); | |
186 | } | |
187 | ||
188 | DH * | |
189 | dh_new_group1() | |
190 | { | |
191 | static char *gen = "2", *group1 = | |
192 | "FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1" | |
193 | "29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD" | |
194 | "EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245" | |
195 | "E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED" | |
196 | "EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381" | |
197 | "FFFFFFFF" "FFFFFFFF"; | |
198 | ||
199 | return (dh_new_group_asc(gen, group1)); | |
200 | } | |
201 | ||
4f8c6159 | 202 | void |
203 | dump_digest(unsigned char *digest, int len) | |
204 | { | |
205 | int i; | |
206 | for (i = 0; i< len; i++){ | |
207 | fprintf(stderr, "%02x", digest[i]); | |
208 | if(i%2!=0) | |
209 | fprintf(stderr, " "); | |
210 | } | |
211 | fprintf(stderr, "\n"); | |
212 | } | |
213 | ||
214 | unsigned char * | |
215 | kex_hash( | |
216 | char *client_version_string, | |
217 | char *server_version_string, | |
218 | char *ckexinit, int ckexinitlen, | |
219 | char *skexinit, int skexinitlen, | |
220 | char *serverhostkeyblob, int sbloblen, | |
221 | BIGNUM *client_dh_pub, | |
222 | BIGNUM *server_dh_pub, | |
223 | BIGNUM *shared_secret) | |
224 | { | |
225 | Buffer b; | |
226 | static unsigned char digest[EVP_MAX_MD_SIZE]; | |
227 | EVP_MD *evp_md = EVP_sha1(); | |
228 | EVP_MD_CTX md; | |
229 | ||
230 | buffer_init(&b); | |
231 | buffer_put_string(&b, client_version_string, strlen(client_version_string)); | |
232 | buffer_put_string(&b, server_version_string, strlen(server_version_string)); | |
233 | ||
234 | /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ | |
235 | buffer_put_int(&b, ckexinitlen+1); | |
236 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | |
237 | buffer_append(&b, ckexinit, ckexinitlen); | |
238 | buffer_put_int(&b, skexinitlen+1); | |
239 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | |
240 | buffer_append(&b, skexinit, skexinitlen); | |
241 | ||
242 | buffer_put_string(&b, serverhostkeyblob, sbloblen); | |
243 | buffer_put_bignum2(&b, client_dh_pub); | |
244 | buffer_put_bignum2(&b, server_dh_pub); | |
245 | buffer_put_bignum2(&b, shared_secret); | |
246 | ||
247 | #ifdef DEBUG_KEX | |
248 | buffer_dump(&b); | |
249 | #endif | |
250 | ||
251 | EVP_DigestInit(&md, evp_md); | |
252 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
253 | EVP_DigestFinal(&md, digest, NULL); | |
254 | ||
255 | buffer_free(&b); | |
256 | ||
257 | #ifdef DEBUG_KEX | |
258 | dump_digest(digest, evp_md->md_size); | |
259 | #endif | |
260 | return digest; | |
261 | } | |
262 | ||
94ec8c6b | 263 | unsigned char * |
264 | kex_hash_gex( | |
265 | char *client_version_string, | |
266 | char *server_version_string, | |
267 | char *ckexinit, int ckexinitlen, | |
268 | char *skexinit, int skexinitlen, | |
269 | char *serverhostkeyblob, int sbloblen, | |
270 | int minbits, BIGNUM *prime, BIGNUM *gen, | |
271 | BIGNUM *client_dh_pub, | |
272 | BIGNUM *server_dh_pub, | |
273 | BIGNUM *shared_secret) | |
274 | { | |
275 | Buffer b; | |
276 | static unsigned char digest[EVP_MAX_MD_SIZE]; | |
277 | EVP_MD *evp_md = EVP_sha1(); | |
278 | EVP_MD_CTX md; | |
279 | ||
280 | buffer_init(&b); | |
281 | buffer_put_string(&b, client_version_string, strlen(client_version_string)); | |
282 | buffer_put_string(&b, server_version_string, strlen(server_version_string)); | |
283 | ||
284 | /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ | |
285 | buffer_put_int(&b, ckexinitlen+1); | |
286 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | |
287 | buffer_append(&b, ckexinit, ckexinitlen); | |
288 | buffer_put_int(&b, skexinitlen+1); | |
289 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | |
290 | buffer_append(&b, skexinit, skexinitlen); | |
291 | ||
292 | buffer_put_string(&b, serverhostkeyblob, sbloblen); | |
293 | buffer_put_int(&b, minbits); | |
294 | buffer_put_bignum2(&b, prime); | |
295 | buffer_put_bignum2(&b, gen); | |
296 | buffer_put_bignum2(&b, client_dh_pub); | |
297 | buffer_put_bignum2(&b, server_dh_pub); | |
298 | buffer_put_bignum2(&b, shared_secret); | |
299 | ||
300 | #ifdef DEBUG_KEX | |
301 | buffer_dump(&b); | |
302 | #endif | |
303 | ||
304 | EVP_DigestInit(&md, evp_md); | |
305 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
306 | EVP_DigestFinal(&md, digest, NULL); | |
307 | ||
308 | buffer_free(&b); | |
309 | ||
310 | #ifdef DEBUG_KEX | |
311 | dump_digest(digest, evp_md->md_size); | |
312 | #endif | |
313 | return digest; | |
314 | } | |
315 | ||
4f8c6159 | 316 | unsigned char * |
317 | derive_key(int id, int need, char unsigned *hash, BIGNUM *shared_secret) | |
318 | { | |
319 | Buffer b; | |
320 | EVP_MD *evp_md = EVP_sha1(); | |
321 | EVP_MD_CTX md; | |
322 | char c = id; | |
323 | int have; | |
324 | int mdsz = evp_md->md_size; | |
325 | unsigned char *digest = xmalloc(((need+mdsz-1)/mdsz)*mdsz); | |
326 | ||
327 | buffer_init(&b); | |
328 | buffer_put_bignum2(&b, shared_secret); | |
329 | ||
330 | EVP_DigestInit(&md, evp_md); | |
331 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); /* shared_secret K */ | |
332 | EVP_DigestUpdate(&md, hash, mdsz); /* transport-06 */ | |
333 | EVP_DigestUpdate(&md, &c, 1); /* key id */ | |
334 | EVP_DigestUpdate(&md, hash, mdsz); /* session id */ | |
335 | EVP_DigestFinal(&md, digest, NULL); | |
336 | ||
337 | /* expand */ | |
338 | for (have = mdsz; need > have; have += mdsz) { | |
339 | EVP_DigestInit(&md, evp_md); | |
340 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
341 | EVP_DigestUpdate(&md, hash, mdsz); | |
342 | EVP_DigestUpdate(&md, digest, have); | |
343 | EVP_DigestFinal(&md, digest + have, NULL); | |
344 | } | |
345 | buffer_free(&b); | |
346 | #ifdef DEBUG_KEX | |
347 | fprintf(stderr, "Digest '%c'== ", c); | |
348 | dump_digest(digest, need); | |
349 | #endif | |
350 | return digest; | |
351 | } | |
352 | ||
353 | #define NKEYS 6 | |
354 | ||
355 | #define MAX_PROP 20 | |
356 | #define SEP "," | |
357 | ||
358 | char * | |
359 | get_match(char *client, char *server) | |
360 | { | |
361 | char *sproposals[MAX_PROP]; | |
089fbbd2 | 362 | char *c, *s, *p, *ret, *cp, *sp; |
4f8c6159 | 363 | int i, j, nproposals; |
364 | ||
089fbbd2 | 365 | c = cp = xstrdup(client); |
366 | s = sp = xstrdup(server); | |
71276795 | 367 | |
089fbbd2 | 368 | for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0'; |
369 | (p = strsep(&sp, SEP)), i++) { | |
4f8c6159 | 370 | if (i < MAX_PROP) |
371 | sproposals[i] = p; | |
372 | else | |
373 | break; | |
374 | } | |
375 | nproposals = i; | |
376 | ||
089fbbd2 | 377 | for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0'; |
378 | (p = strsep(&cp, SEP)), i++) { | |
71276795 | 379 | for (j = 0; j < nproposals; j++) { |
380 | if (strcmp(p, sproposals[j]) == 0) { | |
381 | ret = xstrdup(p); | |
382 | xfree(c); | |
383 | xfree(s); | |
384 | return ret; | |
385 | } | |
386 | } | |
4f8c6159 | 387 | } |
71276795 | 388 | xfree(c); |
389 | xfree(s); | |
4f8c6159 | 390 | return NULL; |
391 | } | |
392 | void | |
393 | choose_enc(Enc *enc, char *client, char *server) | |
394 | { | |
395 | char *name = get_match(client, server); | |
396 | if (name == NULL) | |
397 | fatal("no matching cipher found: client %s server %s", client, server); | |
94ec8c6b | 398 | enc->cipher = cipher_by_name(name); |
399 | if (enc->cipher == NULL) | |
400 | fatal("matching cipher is not supported: %s", name); | |
4f8c6159 | 401 | enc->name = name; |
402 | enc->enabled = 0; | |
403 | enc->iv = NULL; | |
404 | enc->key = NULL; | |
405 | } | |
406 | void | |
407 | choose_mac(Mac *mac, char *client, char *server) | |
408 | { | |
409 | char *name = get_match(client, server); | |
410 | if (name == NULL) | |
411 | fatal("no matching mac found: client %s server %s", client, server); | |
412 | if (strcmp(name, "hmac-md5") == 0) { | |
413 | mac->md = EVP_md5(); | |
414 | } else if (strcmp(name, "hmac-sha1") == 0) { | |
415 | mac->md = EVP_sha1(); | |
416 | } else if (strcmp(name, "hmac-ripemd160@openssh.com") == 0) { | |
417 | mac->md = EVP_ripemd160(); | |
418 | } else { | |
419 | fatal("unsupported mac %s", name); | |
420 | } | |
421 | mac->name = name; | |
422 | mac->mac_len = mac->md->md_size; | |
d0c832f3 | 423 | mac->key_len = (datafellows & SSH_BUG_HMAC) ? 16 : mac->mac_len; |
4f8c6159 | 424 | mac->key = NULL; |
425 | mac->enabled = 0; | |
426 | } | |
427 | void | |
428 | choose_comp(Comp *comp, char *client, char *server) | |
429 | { | |
430 | char *name = get_match(client, server); | |
431 | if (name == NULL) | |
432 | fatal("no matching comp found: client %s server %s", client, server); | |
433 | if (strcmp(name, "zlib") == 0) { | |
434 | comp->type = 1; | |
435 | } else if (strcmp(name, "none") == 0) { | |
436 | comp->type = 0; | |
437 | } else { | |
438 | fatal("unsupported comp %s", name); | |
439 | } | |
440 | comp->name = name; | |
441 | } | |
442 | void | |
443 | choose_kex(Kex *k, char *client, char *server) | |
444 | { | |
445 | k->name = get_match(client, server); | |
446 | if (k->name == NULL) | |
447 | fatal("no kex alg"); | |
94ec8c6b | 448 | if (strcmp(k->name, KEX_DH1) == 0) { |
449 | k->kex_type = DH_GRP1_SHA1; | |
450 | } else if (strcmp(k->name, KEX_DHGEX) == 0) { | |
451 | k->kex_type = DH_GEX_SHA1; | |
452 | } else | |
4f8c6159 | 453 | fatal("bad kex alg %s", k->name); |
454 | } | |
455 | void | |
456 | choose_hostkeyalg(Kex *k, char *client, char *server) | |
457 | { | |
fa08c86b | 458 | char *hostkeyalg = get_match(client, server); |
459 | if (hostkeyalg == NULL) | |
4f8c6159 | 460 | fatal("no hostkey alg"); |
fa08c86b | 461 | k->hostkey_type = key_type_from_name(hostkeyalg); |
462 | if (k->hostkey_type == KEY_UNSPEC) | |
463 | fatal("bad hostkey alg '%s'", hostkeyalg); | |
4f8c6159 | 464 | } |
465 | ||
466 | Kex * | |
467 | kex_choose_conf(char *cprop[PROPOSAL_MAX], char *sprop[PROPOSAL_MAX], int server) | |
468 | { | |
4f8c6159 | 469 | int mode; |
470 | int ctos; /* direction: if true client-to-server */ | |
471 | int need; | |
472 | Kex *k; | |
473 | ||
474 | k = xmalloc(sizeof(*k)); | |
475 | memset(k, 0, sizeof(*k)); | |
476 | k->server = server; | |
477 | ||
478 | for (mode = 0; mode < MODE_MAX; mode++) { | |
479 | int nenc, nmac, ncomp; | |
480 | ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN); | |
481 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; | |
482 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; | |
483 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; | |
484 | choose_enc (&k->enc [mode], cprop[nenc], sprop[nenc]); | |
485 | choose_mac (&k->mac [mode], cprop[nmac], sprop[nmac]); | |
486 | choose_comp(&k->comp[mode], cprop[ncomp], sprop[ncomp]); | |
487 | debug("kex: %s %s %s %s", | |
488 | ctos ? "client->server" : "server->client", | |
489 | k->enc[mode].name, | |
490 | k->mac[mode].name, | |
491 | k->comp[mode].name); | |
492 | } | |
493 | choose_kex(k, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); | |
494 | choose_hostkeyalg(k, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], | |
495 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); | |
4f8c6159 | 496 | need = 0; |
497 | for (mode = 0; mode < MODE_MAX; mode++) { | |
94ec8c6b | 498 | if (need < k->enc[mode].cipher->key_len) |
499 | need = k->enc[mode].cipher->key_len; | |
500 | if (need < k->enc[mode].cipher->block_size) | |
501 | need = k->enc[mode].cipher->block_size; | |
4f8c6159 | 502 | if (need < k->mac[mode].key_len) |
503 | need = k->mac[mode].key_len; | |
504 | } | |
71276795 | 505 | /* XXX need runden? */ |
4f8c6159 | 506 | k->we_need = need; |
507 | return k; | |
508 | } | |
509 | ||
510 | int | |
511 | kex_derive_keys(Kex *k, unsigned char *hash, BIGNUM *shared_secret) | |
512 | { | |
513 | int i; | |
514 | int mode; | |
515 | int ctos; | |
516 | unsigned char *keys[NKEYS]; | |
517 | ||
518 | for (i = 0; i < NKEYS; i++) | |
519 | keys[i] = derive_key('A'+i, k->we_need, hash, shared_secret); | |
520 | ||
521 | for (mode = 0; mode < MODE_MAX; mode++) { | |
522 | ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN); | |
523 | k->enc[mode].iv = keys[ctos ? 0 : 1]; | |
524 | k->enc[mode].key = keys[ctos ? 2 : 3]; | |
525 | k->mac[mode].key = keys[ctos ? 4 : 5]; | |
526 | } | |
527 | return 0; | |
528 | } |