1 /* $OpenBSD: kex.c,v 1.99 2014/04/29 18:01:49 markus 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 <sys/param.h> 27 28 #include <signal.h> 29 #include <stdio.h> 30 #include <stdlib.h> 31 #include <string.h> 32 33 #ifdef WITH_OPENSSL 34 #include <openssl/crypto.h> 35 #endif 36 37 #include "xmalloc.h" 38 #include "ssh2.h" 39 #include "buffer.h" 40 #include "packet.h" 41 #include "compat.h" 42 #include "cipher.h" 43 #include "key.h" 44 #include "kex.h" 45 #include "log.h" 46 #include "mac.h" 47 #include "match.h" 48 #include "dispatch.h" 49 #include "monitor.h" 50 #include "roaming.h" 51 #include "digest.h" 52 53 /* prototype */ 54 static void kex_kexinit_finish(Kex *); 55 static void kex_choose_conf(Kex *); 56 57 struct kexalg { 58 char *name; 59 int type; 60 int ec_nid; 61 int hash_alg; 62 }; 63 static const struct kexalg kexalgs[] = { 64 #ifdef WITH_OPENSSL 65 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 66 { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, 67 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, 68 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 }, 69 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, 70 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, 71 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, 72 SSH_DIGEST_SHA384 }, 73 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, 74 SSH_DIGEST_SHA512 }, 75 #endif 76 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, 77 { NULL, -1, -1, -1}, 78 }; 79 80 char * 81 kex_alg_list(char sep) 82 { 83 char *ret = NULL; 84 size_t nlen, rlen = 0; 85 const struct kexalg *k; 86 87 for (k = kexalgs; k->name != NULL; k++) { 88 if (ret != NULL) 89 ret[rlen++] = sep; 90 nlen = strlen(k->name); 91 ret = xrealloc(ret, 1, rlen + nlen + 2); 92 memcpy(ret + rlen, k->name, nlen + 1); 93 rlen += nlen; 94 } 95 return ret; 96 } 97 98 static const struct kexalg * 99 kex_alg_by_name(const char *name) 100 { 101 const struct kexalg *k; 102 103 for (k = kexalgs; k->name != NULL; k++) { 104 if (strcmp(k->name, name) == 0) 105 return k; 106 } 107 return NULL; 108 } 109 110 /* Validate KEX method name list */ 111 int 112 kex_names_valid(const char *names) 113 { 114 char *s, *cp, *p; 115 116 if (names == NULL || strcmp(names, "") == 0) 117 return 0; 118 s = cp = xstrdup(names); 119 for ((p = strsep(&cp, ",")); p && *p != '\0'; 120 (p = strsep(&cp, ","))) { 121 if (kex_alg_by_name(p) == NULL) { 122 error("Unsupported KEX algorithm \"%.100s\"", p); 123 free(s); 124 return 0; 125 } 126 } 127 debug3("kex names ok: [%s]", names); 128 free(s); 129 return 1; 130 } 131 132 /* put algorithm proposal into buffer */ 133 static void 134 kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) 135 { 136 u_int i; 137 138 buffer_clear(b); 139 /* 140 * add a dummy cookie, the cookie will be overwritten by 141 * kex_send_kexinit(), each time a kexinit is set 142 */ 143 for (i = 0; i < KEX_COOKIE_LEN; i++) 144 buffer_put_char(b, 0); 145 for (i = 0; i < PROPOSAL_MAX; i++) 146 buffer_put_cstring(b, proposal[i]); 147 buffer_put_char(b, 0); /* first_kex_packet_follows */ 148 buffer_put_int(b, 0); /* uint32 reserved */ 149 } 150 151 /* parse buffer and return algorithm proposal */ 152 static char ** 153 kex_buf2prop(Buffer *raw, int *first_kex_follows) 154 { 155 Buffer b; 156 u_int i; 157 char **proposal; 158 159 proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); 160 161 buffer_init(&b); 162 buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); 163 /* skip cookie */ 164 for (i = 0; i < KEX_COOKIE_LEN; i++) 165 buffer_get_char(&b); 166 /* extract kex init proposal strings */ 167 for (i = 0; i < PROPOSAL_MAX; i++) { 168 proposal[i] = buffer_get_cstring(&b,NULL); 169 debug2("kex_parse_kexinit: %s", proposal[i]); 170 } 171 /* first kex follows / reserved */ 172 i = buffer_get_char(&b); 173 if (first_kex_follows != NULL) 174 *first_kex_follows = i; 175 debug2("kex_parse_kexinit: first_kex_follows %d ", i); 176 i = buffer_get_int(&b); 177 debug2("kex_parse_kexinit: reserved %u ", i); 178 buffer_free(&b); 179 return proposal; 180 } 181 182 static void 183 kex_prop_free(char **proposal) 184 { 185 u_int i; 186 187 for (i = 0; i < PROPOSAL_MAX; i++) 188 free(proposal[i]); 189 free(proposal); 190 } 191 192 /* ARGSUSED */ 193 static void 194 kex_protocol_error(int type, u_int32_t seq, void *ctxt) 195 { 196 error("Hm, kex protocol error: type %d seq %u", type, seq); 197 } 198 199 static void 200 kex_reset_dispatch(void) 201 { 202 dispatch_range(SSH2_MSG_TRANSPORT_MIN, 203 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); 204 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 205 } 206 207 void 208 kex_finish(Kex *kex) 209 { 210 kex_reset_dispatch(); 211 212 packet_start(SSH2_MSG_NEWKEYS); 213 packet_send(); 214 /* packet_write_wait(); */ 215 debug("SSH2_MSG_NEWKEYS sent"); 216 217 debug("expecting SSH2_MSG_NEWKEYS"); 218 packet_read_expect(SSH2_MSG_NEWKEYS); 219 packet_check_eom(); 220 debug("SSH2_MSG_NEWKEYS received"); 221 222 kex->done = 1; 223 buffer_clear(&kex->peer); 224 /* buffer_clear(&kex->my); */ 225 kex->flags &= ~KEX_INIT_SENT; 226 free(kex->name); 227 kex->name = NULL; 228 } 229 230 void 231 kex_send_kexinit(Kex *kex) 232 { 233 u_int32_t rnd = 0; 234 u_char *cookie; 235 u_int i; 236 237 if (kex == NULL) { 238 error("kex_send_kexinit: no kex, cannot rekey"); 239 return; 240 } 241 if (kex->flags & KEX_INIT_SENT) { 242 debug("KEX_INIT_SENT"); 243 return; 244 } 245 kex->done = 0; 246 247 /* generate a random cookie */ 248 if (buffer_len(&kex->my) < KEX_COOKIE_LEN) 249 fatal("kex_send_kexinit: kex proposal too short"); 250 cookie = buffer_ptr(&kex->my); 251 for (i = 0; i < KEX_COOKIE_LEN; i++) { 252 if (i % 4 == 0) 253 rnd = arc4random(); 254 cookie[i] = rnd; 255 rnd >>= 8; 256 } 257 packet_start(SSH2_MSG_KEXINIT); 258 packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); 259 packet_send(); 260 debug("SSH2_MSG_KEXINIT sent"); 261 kex->flags |= KEX_INIT_SENT; 262 } 263 264 /* ARGSUSED */ 265 void 266 kex_input_kexinit(int type, u_int32_t seq, void *ctxt) 267 { 268 char *ptr; 269 u_int i, dlen; 270 Kex *kex = (Kex *)ctxt; 271 272 debug("SSH2_MSG_KEXINIT received"); 273 if (kex == NULL) 274 fatal("kex_input_kexinit: no kex, cannot rekey"); 275 276 ptr = packet_get_raw(&dlen); 277 buffer_append(&kex->peer, ptr, dlen); 278 279 /* discard packet */ 280 for (i = 0; i < KEX_COOKIE_LEN; i++) 281 packet_get_char(); 282 for (i = 0; i < PROPOSAL_MAX; i++) 283 free(packet_get_string(NULL)); 284 /* 285 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported 286 * KEX method has the server move first, but a server might be using 287 * a custom method or one that we otherwise don't support. We should 288 * be prepared to remember first_kex_follows here so we can eat a 289 * packet later. 290 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means 291 * for cases where the server *doesn't* go first. I guess we should 292 * ignore it when it is set for these cases, which is what we do now. 293 */ 294 (void) packet_get_char(); /* first_kex_follows */ 295 (void) packet_get_int(); /* reserved */ 296 packet_check_eom(); 297 298 kex_kexinit_finish(kex); 299 } 300 301 Kex * 302 kex_setup(char *proposal[PROPOSAL_MAX]) 303 { 304 Kex *kex; 305 306 kex = xcalloc(1, sizeof(*kex)); 307 buffer_init(&kex->peer); 308 buffer_init(&kex->my); 309 kex_prop2buf(&kex->my, proposal); 310 kex->done = 0; 311 312 kex_send_kexinit(kex); /* we start */ 313 kex_reset_dispatch(); 314 315 return kex; 316 } 317 318 static void 319 kex_kexinit_finish(Kex *kex) 320 { 321 if (!(kex->flags & KEX_INIT_SENT)) 322 kex_send_kexinit(kex); 323 324 kex_choose_conf(kex); 325 326 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && 327 kex->kex[kex->kex_type] != NULL) { 328 (kex->kex[kex->kex_type])(kex); 329 } else { 330 fatal("Unsupported key exchange %d", kex->kex_type); 331 } 332 } 333 334 static void 335 choose_enc(Enc *enc, char *client, char *server) 336 { 337 char *name = match_list(client, server, NULL); 338 if (name == NULL) 339 fatal("no matching cipher found: client %s server %s", 340 client, server); 341 if ((enc->cipher = cipher_by_name(name)) == NULL) 342 fatal("matching cipher is not supported: %s", name); 343 enc->name = name; 344 enc->enabled = 0; 345 enc->iv = NULL; 346 enc->iv_len = cipher_ivlen(enc->cipher); 347 enc->key = NULL; 348 enc->key_len = cipher_keylen(enc->cipher); 349 enc->block_size = cipher_blocksize(enc->cipher); 350 } 351 352 static void 353 choose_mac(Mac *mac, char *client, char *server) 354 { 355 char *name = match_list(client, server, NULL); 356 if (name == NULL) 357 fatal("no matching mac found: client %s server %s", 358 client, server); 359 if (mac_setup(mac, name) < 0) 360 fatal("unsupported mac %s", name); 361 /* truncate the key */ 362 if (datafellows & SSH_BUG_HMAC) 363 mac->key_len = 16; 364 mac->name = name; 365 mac->key = NULL; 366 mac->enabled = 0; 367 } 368 369 static void 370 choose_comp(Comp *comp, char *client, char *server) 371 { 372 char *name = match_list(client, server, NULL); 373 if (name == NULL) 374 fatal("no matching comp found: client %s server %s", client, server); 375 if (strcmp(name, "zlib@openssh.com") == 0) { 376 comp->type = COMP_DELAYED; 377 } else if (strcmp(name, "zlib") == 0) { 378 comp->type = COMP_ZLIB; 379 } else if (strcmp(name, "none") == 0) { 380 comp->type = COMP_NONE; 381 } else { 382 fatal("unsupported comp %s", name); 383 } 384 comp->name = name; 385 } 386 387 static void 388 choose_kex(Kex *k, char *client, char *server) 389 { 390 const struct kexalg *kexalg; 391 392 k->name = match_list(client, server, NULL); 393 if (k->name == NULL) 394 fatal("Unable to negotiate a key exchange method"); 395 if ((kexalg = kex_alg_by_name(k->name)) == NULL) 396 fatal("unsupported kex alg %s", k->name); 397 k->kex_type = kexalg->type; 398 k->hash_alg = kexalg->hash_alg; 399 k->ec_nid = kexalg->ec_nid; 400 } 401 402 static void 403 choose_hostkeyalg(Kex *k, char *client, char *server) 404 { 405 char *hostkeyalg = match_list(client, server, NULL); 406 if (hostkeyalg == NULL) 407 fatal("no hostkey alg"); 408 k->hostkey_type = key_type_from_name(hostkeyalg); 409 if (k->hostkey_type == KEY_UNSPEC) 410 fatal("bad hostkey alg '%s'", hostkeyalg); 411 free(hostkeyalg); 412 } 413 414 static int 415 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) 416 { 417 static int check[] = { 418 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 419 }; 420 int *idx; 421 char *p; 422 423 for (idx = &check[0]; *idx != -1; idx++) { 424 if ((p = strchr(my[*idx], ',')) != NULL) 425 *p = '\0'; 426 if ((p = strchr(peer[*idx], ',')) != NULL) 427 *p = '\0'; 428 if (strcmp(my[*idx], peer[*idx]) != 0) { 429 debug2("proposal mismatch: my %s peer %s", 430 my[*idx], peer[*idx]); 431 return (0); 432 } 433 } 434 debug2("proposals match"); 435 return (1); 436 } 437 438 static void 439 kex_choose_conf(Kex *kex) 440 { 441 Newkeys *newkeys; 442 char **my, **peer; 443 char **cprop, **sprop; 444 int nenc, nmac, ncomp; 445 u_int mode, ctos, need, dh_need, authlen; 446 int first_kex_follows, type; 447 448 my = kex_buf2prop(&kex->my, NULL); 449 peer = kex_buf2prop(&kex->peer, &first_kex_follows); 450 451 if (kex->server) { 452 cprop=peer; 453 sprop=my; 454 } else { 455 cprop=my; 456 sprop=peer; 457 } 458 459 /* Check whether server offers roaming */ 460 if (!kex->server) { 461 char *roaming; 462 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); 463 if (roaming) { 464 kex->roaming = 1; 465 free(roaming); 466 } 467 } 468 469 /* Algorithm Negotiation */ 470 for (mode = 0; mode < MODE_MAX; mode++) { 471 newkeys = xcalloc(1, sizeof(*newkeys)); 472 kex->newkeys[mode] = newkeys; 473 ctos = (!kex->server && mode == MODE_OUT) || 474 (kex->server && mode == MODE_IN); 475 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; 476 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; 477 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; 478 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]); 479 /* ignore mac for authenticated encryption */ 480 authlen = cipher_authlen(newkeys->enc.cipher); 481 if (authlen == 0) 482 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]); 483 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); 484 debug("kex: %s %s %s %s", 485 ctos ? "client->server" : "server->client", 486 newkeys->enc.name, 487 authlen == 0 ? newkeys->mac.name : "<implicit>", 488 newkeys->comp.name); 489 } 490 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); 491 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], 492 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); 493 need = dh_need = 0; 494 for (mode = 0; mode < MODE_MAX; mode++) { 495 newkeys = kex->newkeys[mode]; 496 need = MAX(need, newkeys->enc.key_len); 497 need = MAX(need, newkeys->enc.block_size); 498 need = MAX(need, newkeys->enc.iv_len); 499 need = MAX(need, newkeys->mac.key_len); 500 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher)); 501 dh_need = MAX(dh_need, newkeys->enc.block_size); 502 dh_need = MAX(dh_need, newkeys->enc.iv_len); 503 dh_need = MAX(dh_need, newkeys->mac.key_len); 504 } 505 /* XXX need runden? */ 506 kex->we_need = need; 507 kex->dh_need = dh_need; 508 509 /* ignore the next message if the proposals do not match */ 510 if (first_kex_follows && !proposals_match(my, peer) && 511 !(datafellows & SSH_BUG_FIRSTKEX)) { 512 type = packet_read(); 513 debug2("skipping next packet (type %u)", type); 514 } 515 516 kex_prop_free(my); 517 kex_prop_free(peer); 518 } 519 520 static u_char * 521 derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, 522 const u_char *shared_secret, u_int slen) 523 { 524 Buffer b; 525 struct ssh_digest_ctx *hashctx; 526 char c = id; 527 u_int have; 528 size_t mdsz; 529 u_char *digest; 530 531 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0) 532 fatal("bad kex md size %zu", mdsz); 533 digest = xmalloc(roundup(need, mdsz)); 534 535 buffer_init(&b); 536 buffer_append(&b, shared_secret, slen); 537 538 /* K1 = HASH(K || H || "A" || session_id) */ 539 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 540 fatal("%s: ssh_digest_start failed", __func__); 541 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 542 ssh_digest_update(hashctx, hash, hashlen) != 0 || 543 ssh_digest_update(hashctx, &c, 1) != 0 || 544 ssh_digest_update(hashctx, kex->session_id, 545 kex->session_id_len) != 0) 546 fatal("%s: ssh_digest_update failed", __func__); 547 if (ssh_digest_final(hashctx, digest, mdsz) != 0) 548 fatal("%s: ssh_digest_final failed", __func__); 549 ssh_digest_free(hashctx); 550 551 /* 552 * expand key: 553 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) 554 * Key = K1 || K2 || ... || Kn 555 */ 556 for (have = mdsz; need > have; have += mdsz) { 557 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 558 fatal("%s: ssh_digest_start failed", __func__); 559 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 560 ssh_digest_update(hashctx, hash, hashlen) != 0 || 561 ssh_digest_update(hashctx, digest, have) != 0) 562 fatal("%s: ssh_digest_update failed", __func__); 563 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0) 564 fatal("%s: ssh_digest_final failed", __func__); 565 ssh_digest_free(hashctx); 566 } 567 buffer_free(&b); 568 #ifdef DEBUG_KEX 569 fprintf(stderr, "key '%c'== ", c); 570 dump_digest("key", digest, need); 571 #endif 572 return digest; 573 } 574 575 Newkeys *current_keys[MODE_MAX]; 576 577 #define NKEYS 6 578 void 579 kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, 580 const u_char *shared_secret, u_int slen) 581 { 582 u_char *keys[NKEYS]; 583 u_int i, mode, ctos; 584 585 for (i = 0; i < NKEYS; i++) { 586 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, 587 shared_secret, slen); 588 } 589 590 debug2("kex_derive_keys"); 591 for (mode = 0; mode < MODE_MAX; mode++) { 592 current_keys[mode] = kex->newkeys[mode]; 593 kex->newkeys[mode] = NULL; 594 ctos = (!kex->server && mode == MODE_OUT) || 595 (kex->server && mode == MODE_IN); 596 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; 597 current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; 598 current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; 599 } 600 } 601 602 #ifdef WITH_OPENSSL 603 void 604 kex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret) 605 { 606 Buffer shared_secret; 607 608 buffer_init(&shared_secret); 609 buffer_put_bignum2(&shared_secret, secret); 610 kex_derive_keys(kex, hash, hashlen, 611 buffer_ptr(&shared_secret), buffer_len(&shared_secret)); 612 buffer_free(&shared_secret); 613 } 614 #endif 615 616 Newkeys * 617 kex_get_newkeys(int mode) 618 { 619 Newkeys *ret; 620 621 ret = current_keys[mode]; 622 current_keys[mode] = NULL; 623 return ret; 624 } 625 626 #ifdef WITH_SSH1 627 void 628 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, 629 u_int8_t cookie[8], u_int8_t id[16]) 630 { 631 u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH]; 632 int len; 633 struct ssh_digest_ctx *hashctx; 634 635 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) 636 fatal("%s: ssh_digest_start", __func__); 637 638 len = BN_num_bytes(host_modulus); 639 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 640 fatal("%s: bad host modulus (len %d)", __func__, len); 641 BN_bn2bin(host_modulus, nbuf); 642 if (ssh_digest_update(hashctx, nbuf, len) != 0) 643 fatal("%s: ssh_digest_update failed", __func__); 644 645 len = BN_num_bytes(server_modulus); 646 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 647 fatal("%s: bad server modulus (len %d)", __func__, len); 648 BN_bn2bin(server_modulus, nbuf); 649 if (ssh_digest_update(hashctx, nbuf, len) != 0 || 650 ssh_digest_update(hashctx, cookie, 8) != 0) 651 fatal("%s: ssh_digest_update failed", __func__); 652 if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) 653 fatal("%s: ssh_digest_final failed", __func__); 654 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5)); 655 656 explicit_bzero(nbuf, sizeof(nbuf)); 657 explicit_bzero(obuf, sizeof(obuf)); 658 } 659 #endif 660 661 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 662 void 663 dump_digest(char *msg, u_char *digest, int len) 664 { 665 int i; 666 667 fprintf(stderr, "%s\n", msg); 668 for (i = 0; i < len; i++) { 669 fprintf(stderr, "%02x", digest[i]); 670 if (i%32 == 31) 671 fprintf(stderr, "\n"); 672 else if (i%8 == 7) 673 fprintf(stderr, " "); 674 } 675 fprintf(stderr, "\n"); 676 } 677 #endif 678