kex.c revision 291198
1/* $OpenBSD: kex.c,v 1.98 2014/02/02 03:44:31 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#include "roaming.h" 52#include "digest.h" 53 54#if OPENSSL_VERSION_NUMBER >= 0x00907000L 55# if defined(HAVE_EVP_SHA256) 56# define evp_ssh_sha256 EVP_sha256 57# else 58extern const EVP_MD *evp_ssh_sha256(void); 59# endif 60#endif 61 62/* prototype */ 63static void kex_kexinit_finish(Kex *); 64static void kex_choose_conf(Kex *); 65 66struct kexalg { 67 char *name; 68 int type; 69 int ec_nid; 70 int hash_alg; 71}; 72static const struct kexalg kexalgs[] = { 73 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 74 { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, 75 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, 76#ifdef HAVE_EVP_SHA256 77 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 }, 78#endif 79#ifdef OPENSSL_HAS_ECC 80 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, 81 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, 82 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, 83 SSH_DIGEST_SHA384 }, 84# ifdef OPENSSL_HAS_NISTP521 85 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, 86 SSH_DIGEST_SHA512 }, 87# endif 88#endif 89 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 90#ifdef HAVE_EVP_SHA256 91 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, 92#endif 93 { NULL, -1, -1, -1}, 94}; 95 96char * 97kex_alg_list(char sep) 98{ 99 char *ret = NULL; 100 size_t nlen, rlen = 0; 101 const struct kexalg *k; 102 103 for (k = kexalgs; k->name != NULL; k++) { 104 if (ret != NULL) 105 ret[rlen++] = sep; 106 nlen = strlen(k->name); 107 ret = xrealloc(ret, 1, rlen + nlen + 2); 108 memcpy(ret + rlen, k->name, nlen + 1); 109 rlen += nlen; 110 } 111 return ret; 112} 113 114static const struct kexalg * 115kex_alg_by_name(const char *name) 116{ 117 const struct kexalg *k; 118 119 for (k = kexalgs; k->name != NULL; k++) { 120 if (strcmp(k->name, name) == 0) 121 return k; 122 } 123 return NULL; 124} 125 126/* Validate KEX method name list */ 127int 128kex_names_valid(const char *names) 129{ 130 char *s, *cp, *p; 131 132 if (names == NULL || strcmp(names, "") == 0) 133 return 0; 134 s = cp = xstrdup(names); 135 for ((p = strsep(&cp, ",")); p && *p != '\0'; 136 (p = strsep(&cp, ","))) { 137 if (kex_alg_by_name(p) == NULL) { 138 error("Unsupported KEX algorithm \"%.100s\"", p); 139 free(s); 140 return 0; 141 } 142 } 143 debug3("kex names ok: [%s]", names); 144 free(s); 145 return 1; 146} 147 148/* put algorithm proposal into buffer */ 149static void 150kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) 151{ 152 u_int i; 153 154 buffer_clear(b); 155 /* 156 * add a dummy cookie, the cookie will be overwritten by 157 * kex_send_kexinit(), each time a kexinit is set 158 */ 159 for (i = 0; i < KEX_COOKIE_LEN; i++) 160 buffer_put_char(b, 0); 161 for (i = 0; i < PROPOSAL_MAX; i++) 162 buffer_put_cstring(b, proposal[i]); 163 buffer_put_char(b, 0); /* first_kex_packet_follows */ 164 buffer_put_int(b, 0); /* uint32 reserved */ 165} 166 167/* parse buffer and return algorithm proposal */ 168static char ** 169kex_buf2prop(Buffer *raw, int *first_kex_follows) 170{ 171 Buffer b; 172 u_int i; 173 char **proposal; 174 175 proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); 176 177 buffer_init(&b); 178 buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); 179 /* skip cookie */ 180 for (i = 0; i < KEX_COOKIE_LEN; i++) 181 buffer_get_char(&b); 182 /* extract kex init proposal strings */ 183 for (i = 0; i < PROPOSAL_MAX; i++) { 184 proposal[i] = buffer_get_cstring(&b,NULL); 185 debug2("kex_parse_kexinit: %s", proposal[i]); 186 } 187 /* first kex follows / reserved */ 188 i = buffer_get_char(&b); 189 if (first_kex_follows != NULL) 190 *first_kex_follows = i; 191 debug2("kex_parse_kexinit: first_kex_follows %d ", i); 192 i = buffer_get_int(&b); 193 debug2("kex_parse_kexinit: reserved %u ", i); 194 buffer_free(&b); 195 return proposal; 196} 197 198static void 199kex_prop_free(char **proposal) 200{ 201 u_int i; 202 203 for (i = 0; i < PROPOSAL_MAX; i++) 204 free(proposal[i]); 205 free(proposal); 206} 207 208/* ARGSUSED */ 209static void 210kex_protocol_error(int type, u_int32_t seq, void *ctxt) 211{ 212 error("Hm, kex protocol error: type %d seq %u", type, seq); 213} 214 215static void 216kex_reset_dispatch(void) 217{ 218 dispatch_range(SSH2_MSG_TRANSPORT_MIN, 219 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); 220 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 221} 222 223void 224kex_finish(Kex *kex) 225{ 226 kex_reset_dispatch(); 227 228 packet_start(SSH2_MSG_NEWKEYS); 229 packet_send(); 230 /* packet_write_wait(); */ 231 debug("SSH2_MSG_NEWKEYS sent"); 232 233 debug("expecting SSH2_MSG_NEWKEYS"); 234 packet_read_expect(SSH2_MSG_NEWKEYS); 235 packet_check_eom(); 236 debug("SSH2_MSG_NEWKEYS received"); 237 238 kex->done = 1; 239 buffer_clear(&kex->peer); 240 /* buffer_clear(&kex->my); */ 241 kex->flags &= ~KEX_INIT_SENT; 242 free(kex->name); 243 kex->name = NULL; 244} 245 246void 247kex_send_kexinit(Kex *kex) 248{ 249 u_int32_t rnd = 0; 250 u_char *cookie; 251 u_int i; 252 253 if (kex == NULL) { 254 error("kex_send_kexinit: no kex, cannot rekey"); 255 return; 256 } 257 if (kex->flags & KEX_INIT_SENT) { 258 debug("KEX_INIT_SENT"); 259 return; 260 } 261 kex->done = 0; 262 263 /* generate a random cookie */ 264 if (buffer_len(&kex->my) < KEX_COOKIE_LEN) 265 fatal("kex_send_kexinit: kex proposal too short"); 266 cookie = buffer_ptr(&kex->my); 267 for (i = 0; i < KEX_COOKIE_LEN; i++) { 268 if (i % 4 == 0) 269 rnd = arc4random(); 270 cookie[i] = rnd; 271 rnd >>= 8; 272 } 273 packet_start(SSH2_MSG_KEXINIT); 274 packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); 275 packet_send(); 276 debug("SSH2_MSG_KEXINIT sent"); 277 kex->flags |= KEX_INIT_SENT; 278} 279 280/* ARGSUSED */ 281void 282kex_input_kexinit(int type, u_int32_t seq, void *ctxt) 283{ 284 char *ptr; 285 u_int i, dlen; 286 Kex *kex = (Kex *)ctxt; 287 288 debug("SSH2_MSG_KEXINIT received"); 289 if (kex == NULL) 290 fatal("kex_input_kexinit: no kex, cannot rekey"); 291 292 ptr = packet_get_raw(&dlen); 293 buffer_append(&kex->peer, ptr, dlen); 294 295 /* discard packet */ 296 for (i = 0; i < KEX_COOKIE_LEN; i++) 297 packet_get_char(); 298 for (i = 0; i < PROPOSAL_MAX; i++) 299 free(packet_get_string(NULL)); 300 /* 301 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported 302 * KEX method has the server move first, but a server might be using 303 * a custom method or one that we otherwise don't support. We should 304 * be prepared to remember first_kex_follows here so we can eat a 305 * packet later. 306 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means 307 * for cases where the server *doesn't* go first. I guess we should 308 * ignore it when it is set for these cases, which is what we do now. 309 */ 310 (void) packet_get_char(); /* first_kex_follows */ 311 (void) packet_get_int(); /* reserved */ 312 packet_check_eom(); 313 314 kex_kexinit_finish(kex); 315} 316 317Kex * 318kex_setup(char *proposal[PROPOSAL_MAX]) 319{ 320 Kex *kex; 321 322 kex = xcalloc(1, sizeof(*kex)); 323 buffer_init(&kex->peer); 324 buffer_init(&kex->my); 325 kex_prop2buf(&kex->my, proposal); 326 kex->done = 0; 327 328 kex_send_kexinit(kex); /* we start */ 329 kex_reset_dispatch(); 330 331 return kex; 332} 333 334static void 335kex_kexinit_finish(Kex *kex) 336{ 337 if (!(kex->flags & KEX_INIT_SENT)) 338 kex_send_kexinit(kex); 339 340 kex_choose_conf(kex); 341 342 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && 343 kex->kex[kex->kex_type] != NULL) { 344 (kex->kex[kex->kex_type])(kex); 345 } else { 346 fatal("Unsupported key exchange %d", kex->kex_type); 347 } 348} 349 350static void 351choose_enc(Enc *enc, char *client, char *server) 352{ 353 char *name = match_list(client, server, NULL); 354 if (name == NULL) 355 fatal("no matching cipher found: client %s server %s", 356 client, server); 357 if ((enc->cipher = cipher_by_name(name)) == NULL) 358 fatal("matching cipher is not supported: %s", name); 359 enc->name = name; 360 enc->enabled = 0; 361 enc->iv = NULL; 362 enc->iv_len = cipher_ivlen(enc->cipher); 363 enc->key = NULL; 364 enc->key_len = cipher_keylen(enc->cipher); 365 enc->block_size = cipher_blocksize(enc->cipher); 366} 367 368static void 369choose_mac(Mac *mac, char *client, char *server) 370{ 371 char *name = match_list(client, server, NULL); 372 if (name == NULL) 373 fatal("no matching mac found: client %s server %s", 374 client, server); 375 if (mac_setup(mac, name) < 0) 376 fatal("unsupported mac %s", name); 377 /* truncate the key */ 378 if (datafellows & SSH_BUG_HMAC) 379 mac->key_len = 16; 380 mac->name = name; 381 mac->key = NULL; 382 mac->enabled = 0; 383} 384 385static void 386choose_comp(Comp *comp, char *client, char *server) 387{ 388 char *name = match_list(client, server, NULL); 389 if (name == NULL) 390 fatal("no matching comp found: client %s server %s", client, server); 391 if (strcmp(name, "zlib@openssh.com") == 0) { 392 comp->type = COMP_DELAYED; 393 } else if (strcmp(name, "zlib") == 0) { 394 comp->type = COMP_ZLIB; 395 } else if (strcmp(name, "none") == 0) { 396 comp->type = COMP_NONE; 397 } else { 398 fatal("unsupported comp %s", name); 399 } 400 comp->name = name; 401} 402 403static void 404choose_kex(Kex *k, char *client, char *server) 405{ 406 const struct kexalg *kexalg; 407 408 k->name = match_list(client, server, NULL); 409 if (k->name == NULL) 410 fatal("Unable to negotiate a key exchange method"); 411 if ((kexalg = kex_alg_by_name(k->name)) == NULL) 412 fatal("unsupported kex alg %s", k->name); 413 k->kex_type = kexalg->type; 414 k->hash_alg = kexalg->hash_alg; 415 k->ec_nid = kexalg->ec_nid; 416} 417 418static void 419choose_hostkeyalg(Kex *k, char *client, char *server) 420{ 421 char *hostkeyalg = match_list(client, server, NULL); 422 if (hostkeyalg == NULL) 423 fatal("no hostkey alg"); 424 k->hostkey_type = key_type_from_name(hostkeyalg); 425 if (k->hostkey_type == KEY_UNSPEC) 426 fatal("bad hostkey alg '%s'", hostkeyalg); 427 free(hostkeyalg); 428} 429 430static int 431proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) 432{ 433 static int check[] = { 434 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 435 }; 436 int *idx; 437 char *p; 438 439 for (idx = &check[0]; *idx != -1; idx++) { 440 if ((p = strchr(my[*idx], ',')) != NULL) 441 *p = '\0'; 442 if ((p = strchr(peer[*idx], ',')) != NULL) 443 *p = '\0'; 444 if (strcmp(my[*idx], peer[*idx]) != 0) { 445 debug2("proposal mismatch: my %s peer %s", 446 my[*idx], peer[*idx]); 447 return (0); 448 } 449 } 450 debug2("proposals match"); 451 return (1); 452} 453 454static void 455kex_choose_conf(Kex *kex) 456{ 457 Newkeys *newkeys; 458 char **my, **peer; 459 char **cprop, **sprop; 460 int nenc, nmac, ncomp; 461 u_int mode, ctos, need, dh_need, authlen; 462 int first_kex_follows, type; 463 464 my = kex_buf2prop(&kex->my, NULL); 465 peer = kex_buf2prop(&kex->peer, &first_kex_follows); 466 467 if (kex->server) { 468 cprop=peer; 469 sprop=my; 470 } else { 471 cprop=my; 472 sprop=peer; 473 } 474 475 /* Check whether server offers roaming */ 476 if (!kex->server) { 477 char *roaming; 478 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); 479 if (roaming) { 480 kex->roaming = 1; 481 free(roaming); 482 } 483 } 484 485 /* Algorithm Negotiation */ 486 for (mode = 0; mode < MODE_MAX; mode++) { 487 newkeys = xcalloc(1, sizeof(*newkeys)); 488 kex->newkeys[mode] = newkeys; 489 ctos = (!kex->server && mode == MODE_OUT) || 490 (kex->server && mode == MODE_IN); 491 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; 492 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; 493 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; 494 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]); 495 /* ignore mac for authenticated encryption */ 496 authlen = cipher_authlen(newkeys->enc.cipher); 497 if (authlen == 0) 498 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]); 499 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); 500 debug("kex: %s %s %s %s", 501 ctos ? "client->server" : "server->client", 502 newkeys->enc.name, 503 authlen == 0 ? newkeys->mac.name : "<implicit>", 504 newkeys->comp.name); 505 } 506 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); 507 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], 508 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); 509 need = dh_need = 0; 510 for (mode = 0; mode < MODE_MAX; mode++) { 511 newkeys = kex->newkeys[mode]; 512 need = MAX(need, newkeys->enc.key_len); 513 need = MAX(need, newkeys->enc.block_size); 514 need = MAX(need, newkeys->enc.iv_len); 515 need = MAX(need, newkeys->mac.key_len); 516 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher)); 517 dh_need = MAX(dh_need, newkeys->enc.block_size); 518 dh_need = MAX(dh_need, newkeys->enc.iv_len); 519 dh_need = MAX(dh_need, newkeys->mac.key_len); 520 } 521 /* XXX need runden? */ 522 kex->we_need = need; 523 kex->dh_need = dh_need; 524 525 /* ignore the next message if the proposals do not match */ 526 if (first_kex_follows && !proposals_match(my, peer) && 527 !(datafellows & SSH_BUG_FIRSTKEX)) { 528 type = packet_read(); 529 debug2("skipping next packet (type %u)", type); 530 } 531 532 kex_prop_free(my); 533 kex_prop_free(peer); 534} 535 536static u_char * 537derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, 538 const u_char *shared_secret, u_int slen) 539{ 540 Buffer b; 541 struct ssh_digest_ctx *hashctx; 542 char c = id; 543 u_int have; 544 size_t mdsz; 545 u_char *digest; 546 547 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0) 548 fatal("bad kex md size %zu", mdsz); 549 digest = xmalloc(roundup(need, mdsz)); 550 551 buffer_init(&b); 552 buffer_append(&b, shared_secret, slen); 553 554 /* K1 = HASH(K || H || "A" || session_id) */ 555 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 556 fatal("%s: ssh_digest_start failed", __func__); 557 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 558 ssh_digest_update(hashctx, hash, hashlen) != 0 || 559 ssh_digest_update(hashctx, &c, 1) != 0 || 560 ssh_digest_update(hashctx, kex->session_id, 561 kex->session_id_len) != 0) 562 fatal("%s: ssh_digest_update failed", __func__); 563 if (ssh_digest_final(hashctx, digest, mdsz) != 0) 564 fatal("%s: ssh_digest_final failed", __func__); 565 ssh_digest_free(hashctx); 566 567 /* 568 * expand key: 569 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) 570 * Key = K1 || K2 || ... || Kn 571 */ 572 for (have = mdsz; need > have; have += mdsz) { 573 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 574 fatal("%s: ssh_digest_start failed", __func__); 575 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 576 ssh_digest_update(hashctx, hash, hashlen) != 0 || 577 ssh_digest_update(hashctx, digest, have) != 0) 578 fatal("%s: ssh_digest_update failed", __func__); 579 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0) 580 fatal("%s: ssh_digest_final failed", __func__); 581 ssh_digest_free(hashctx); 582 } 583 buffer_free(&b); 584#ifdef DEBUG_KEX 585 fprintf(stderr, "key '%c'== ", c); 586 dump_digest("key", digest, need); 587#endif 588 return digest; 589} 590 591Newkeys *current_keys[MODE_MAX]; 592 593#define NKEYS 6 594void 595kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, 596 const u_char *shared_secret, u_int slen) 597{ 598 u_char *keys[NKEYS]; 599 u_int i, mode, ctos; 600 601 for (i = 0; i < NKEYS; i++) { 602 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, 603 shared_secret, slen); 604 } 605 606 debug2("kex_derive_keys"); 607 for (mode = 0; mode < MODE_MAX; mode++) { 608 current_keys[mode] = kex->newkeys[mode]; 609 kex->newkeys[mode] = NULL; 610 ctos = (!kex->server && mode == MODE_OUT) || 611 (kex->server && mode == MODE_IN); 612 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; 613 current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; 614 current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; 615 } 616} 617 618void 619kex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret) 620{ 621 Buffer shared_secret; 622 623 buffer_init(&shared_secret); 624 buffer_put_bignum2(&shared_secret, secret); 625 kex_derive_keys(kex, hash, hashlen, 626 buffer_ptr(&shared_secret), buffer_len(&shared_secret)); 627 buffer_free(&shared_secret); 628} 629 630Newkeys * 631kex_get_newkeys(int mode) 632{ 633 Newkeys *ret; 634 635 ret = current_keys[mode]; 636 current_keys[mode] = NULL; 637 return ret; 638} 639 640void 641derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, 642 u_int8_t cookie[8], u_int8_t id[16]) 643{ 644 u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH]; 645 int len; 646 struct ssh_digest_ctx *hashctx; 647 648 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) 649 fatal("%s: ssh_digest_start", __func__); 650 651 len = BN_num_bytes(host_modulus); 652 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 653 fatal("%s: bad host modulus (len %d)", __func__, len); 654 BN_bn2bin(host_modulus, nbuf); 655 if (ssh_digest_update(hashctx, nbuf, len) != 0) 656 fatal("%s: ssh_digest_update failed", __func__); 657 658 len = BN_num_bytes(server_modulus); 659 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 660 fatal("%s: bad server modulus (len %d)", __func__, len); 661 BN_bn2bin(server_modulus, nbuf); 662 if (ssh_digest_update(hashctx, nbuf, len) != 0 || 663 ssh_digest_update(hashctx, cookie, 8) != 0) 664 fatal("%s: ssh_digest_update failed", __func__); 665 if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) 666 fatal("%s: ssh_digest_final failed", __func__); 667 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5)); 668 669 explicit_bzero(nbuf, sizeof(nbuf)); 670 explicit_bzero(obuf, sizeof(obuf)); 671} 672 673#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 674void 675dump_digest(char *msg, u_char *digest, int len) 676{ 677 int i; 678 679 fprintf(stderr, "%s\n", msg); 680 for (i = 0; i < len; i++) { 681 fprintf(stderr, "%02x", digest[i]); 682 if (i%32 == 31) 683 fprintf(stderr, "\n"); 684 else if (i%8 == 7) 685 fprintf(stderr, " "); 686 } 687 fprintf(stderr, "\n"); 688} 689#endif 690