kex.c revision 1.94
1/* $OpenBSD: kex.c,v 1.94 2014/01/09 23:20:00 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 <sys/param.h> 27 28#include <signal.h> 29#include <stdio.h> 30#include <stdlib.h> 31#include <string.h> 32 33#include <openssl/crypto.h> 34 35#include "xmalloc.h" 36#include "ssh2.h" 37#include "buffer.h" 38#include "packet.h" 39#include "compat.h" 40#include "cipher.h" 41#include "key.h" 42#include "kex.h" 43#include "log.h" 44#include "mac.h" 45#include "match.h" 46#include "dispatch.h" 47#include "monitor.h" 48#include "roaming.h" 49#include "digest.h" 50 51/* prototype */ 52static void kex_kexinit_finish(Kex *); 53static void kex_choose_conf(Kex *); 54 55struct kexalg { 56 char *name; 57 int type; 58 int ec_nid; 59 int hash_alg; 60}; 61static const struct kexalg kexalgs[] = { 62 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 63 { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, 64 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, 65 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 }, 66 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, 67 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, 68 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, 69 SSH_DIGEST_SHA384 }, 70 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, 71 SSH_DIGEST_SHA512 }, 72 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, 73 { NULL, -1, -1, -1}, 74}; 75 76char * 77kex_alg_list(char sep) 78{ 79 char *ret = NULL; 80 size_t nlen, rlen = 0; 81 const struct kexalg *k; 82 83 for (k = kexalgs; k->name != NULL; k++) { 84 if (ret != NULL) 85 ret[rlen++] = sep; 86 nlen = strlen(k->name); 87 ret = xrealloc(ret, 1, rlen + nlen + 2); 88 memcpy(ret + rlen, k->name, nlen + 1); 89 rlen += nlen; 90 } 91 return ret; 92} 93 94static const struct kexalg * 95kex_alg_by_name(const char *name) 96{ 97 const struct kexalg *k; 98 99 for (k = kexalgs; k->name != NULL; k++) { 100 if (strcmp(k->name, name) == 0) 101 return k; 102 } 103 return NULL; 104} 105 106/* Validate KEX method name list */ 107int 108kex_names_valid(const char *names) 109{ 110 char *s, *cp, *p; 111 112 if (names == NULL || strcmp(names, "") == 0) 113 return 0; 114 s = cp = xstrdup(names); 115 for ((p = strsep(&cp, ",")); p && *p != '\0'; 116 (p = strsep(&cp, ","))) { 117 if (kex_alg_by_name(p) == NULL) { 118 error("Unsupported KEX algorithm \"%.100s\"", p); 119 free(s); 120 return 0; 121 } 122 } 123 debug3("kex names ok: [%s]", names); 124 free(s); 125 return 1; 126} 127 128/* put algorithm proposal into buffer */ 129static void 130kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) 131{ 132 u_int i; 133 134 buffer_clear(b); 135 /* 136 * add a dummy cookie, the cookie will be overwritten by 137 * kex_send_kexinit(), each time a kexinit is set 138 */ 139 for (i = 0; i < KEX_COOKIE_LEN; i++) 140 buffer_put_char(b, 0); 141 for (i = 0; i < PROPOSAL_MAX; i++) 142 buffer_put_cstring(b, proposal[i]); 143 buffer_put_char(b, 0); /* first_kex_packet_follows */ 144 buffer_put_int(b, 0); /* uint32 reserved */ 145} 146 147/* parse buffer and return algorithm proposal */ 148static char ** 149kex_buf2prop(Buffer *raw, int *first_kex_follows) 150{ 151 Buffer b; 152 u_int i; 153 char **proposal; 154 155 proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); 156 157 buffer_init(&b); 158 buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); 159 /* skip cookie */ 160 for (i = 0; i < KEX_COOKIE_LEN; i++) 161 buffer_get_char(&b); 162 /* extract kex init proposal strings */ 163 for (i = 0; i < PROPOSAL_MAX; i++) { 164 proposal[i] = buffer_get_cstring(&b,NULL); 165 debug2("kex_parse_kexinit: %s", proposal[i]); 166 } 167 /* first kex follows / reserved */ 168 i = buffer_get_char(&b); 169 if (first_kex_follows != NULL) 170 *first_kex_follows = i; 171 debug2("kex_parse_kexinit: first_kex_follows %d ", i); 172 i = buffer_get_int(&b); 173 debug2("kex_parse_kexinit: reserved %u ", i); 174 buffer_free(&b); 175 return proposal; 176} 177 178static void 179kex_prop_free(char **proposal) 180{ 181 u_int i; 182 183 for (i = 0; i < PROPOSAL_MAX; i++) 184 free(proposal[i]); 185 free(proposal); 186} 187 188/* ARGSUSED */ 189static void 190kex_protocol_error(int type, u_int32_t seq, void *ctxt) 191{ 192 error("Hm, kex protocol error: type %d seq %u", type, seq); 193} 194 195static void 196kex_reset_dispatch(void) 197{ 198 dispatch_range(SSH2_MSG_TRANSPORT_MIN, 199 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); 200 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 201} 202 203void 204kex_finish(Kex *kex) 205{ 206 kex_reset_dispatch(); 207 208 packet_start(SSH2_MSG_NEWKEYS); 209 packet_send(); 210 /* packet_write_wait(); */ 211 debug("SSH2_MSG_NEWKEYS sent"); 212 213 debug("expecting SSH2_MSG_NEWKEYS"); 214 packet_read_expect(SSH2_MSG_NEWKEYS); 215 packet_check_eom(); 216 debug("SSH2_MSG_NEWKEYS received"); 217 218 kex->done = 1; 219 buffer_clear(&kex->peer); 220 /* buffer_clear(&kex->my); */ 221 kex->flags &= ~KEX_INIT_SENT; 222 free(kex->name); 223 kex->name = NULL; 224} 225 226void 227kex_send_kexinit(Kex *kex) 228{ 229 u_int32_t rnd = 0; 230 u_char *cookie; 231 u_int i; 232 233 if (kex == NULL) { 234 error("kex_send_kexinit: no kex, cannot rekey"); 235 return; 236 } 237 if (kex->flags & KEX_INIT_SENT) { 238 debug("KEX_INIT_SENT"); 239 return; 240 } 241 kex->done = 0; 242 243 /* generate a random cookie */ 244 if (buffer_len(&kex->my) < KEX_COOKIE_LEN) 245 fatal("kex_send_kexinit: kex proposal too short"); 246 cookie = buffer_ptr(&kex->my); 247 for (i = 0; i < KEX_COOKIE_LEN; i++) { 248 if (i % 4 == 0) 249 rnd = arc4random(); 250 cookie[i] = rnd; 251 rnd >>= 8; 252 } 253 packet_start(SSH2_MSG_KEXINIT); 254 packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); 255 packet_send(); 256 debug("SSH2_MSG_KEXINIT sent"); 257 kex->flags |= KEX_INIT_SENT; 258} 259 260/* ARGSUSED */ 261void 262kex_input_kexinit(int type, u_int32_t seq, void *ctxt) 263{ 264 char *ptr; 265 u_int i, dlen; 266 Kex *kex = (Kex *)ctxt; 267 268 debug("SSH2_MSG_KEXINIT received"); 269 if (kex == NULL) 270 fatal("kex_input_kexinit: no kex, cannot rekey"); 271 272 ptr = packet_get_raw(&dlen); 273 buffer_append(&kex->peer, ptr, dlen); 274 275 /* discard packet */ 276 for (i = 0; i < KEX_COOKIE_LEN; i++) 277 packet_get_char(); 278 for (i = 0; i < PROPOSAL_MAX; i++) 279 free(packet_get_string(NULL)); 280 /* 281 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported 282 * KEX method has the server move first, but a server might be using 283 * a custom method or one that we otherwise don't support. We should 284 * be prepared to remember first_kex_follows here so we can eat a 285 * packet later. 286 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means 287 * for cases where the server *doesn't* go first. I guess we should 288 * ignore it when it is set for these cases, which is what we do now. 289 */ 290 (void) packet_get_char(); /* first_kex_follows */ 291 (void) packet_get_int(); /* reserved */ 292 packet_check_eom(); 293 294 kex_kexinit_finish(kex); 295} 296 297Kex * 298kex_setup(char *proposal[PROPOSAL_MAX]) 299{ 300 Kex *kex; 301 302 kex = xcalloc(1, sizeof(*kex)); 303 buffer_init(&kex->peer); 304 buffer_init(&kex->my); 305 kex_prop2buf(&kex->my, proposal); 306 kex->done = 0; 307 308 kex_send_kexinit(kex); /* we start */ 309 kex_reset_dispatch(); 310 311 return kex; 312} 313 314static void 315kex_kexinit_finish(Kex *kex) 316{ 317 if (!(kex->flags & KEX_INIT_SENT)) 318 kex_send_kexinit(kex); 319 320 kex_choose_conf(kex); 321 322 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && 323 kex->kex[kex->kex_type] != NULL) { 324 (kex->kex[kex->kex_type])(kex); 325 } else { 326 fatal("Unsupported key exchange %d", kex->kex_type); 327 } 328} 329 330static void 331choose_enc(Enc *enc, char *client, char *server) 332{ 333 char *name = match_list(client, server, NULL); 334 if (name == NULL) 335 fatal("no matching cipher found: client %s server %s", 336 client, server); 337 if ((enc->cipher = cipher_by_name(name)) == NULL) 338 fatal("matching cipher is not supported: %s", name); 339 enc->name = name; 340 enc->enabled = 0; 341 enc->iv = NULL; 342 enc->iv_len = cipher_ivlen(enc->cipher); 343 enc->key = NULL; 344 enc->key_len = cipher_keylen(enc->cipher); 345 enc->block_size = cipher_blocksize(enc->cipher); 346} 347 348static void 349choose_mac(Mac *mac, char *client, char *server) 350{ 351 char *name = match_list(client, server, NULL); 352 if (name == NULL) 353 fatal("no matching mac found: client %s server %s", 354 client, server); 355 if (mac_setup(mac, name) < 0) 356 fatal("unsupported mac %s", name); 357 /* truncate the key */ 358 if (datafellows & SSH_BUG_HMAC) 359 mac->key_len = 16; 360 mac->name = name; 361 mac->key = NULL; 362 mac->enabled = 0; 363} 364 365static void 366choose_comp(Comp *comp, char *client, char *server) 367{ 368 char *name = match_list(client, server, NULL); 369 if (name == NULL) 370 fatal("no matching comp found: client %s server %s", client, server); 371 if (strcmp(name, "zlib@openssh.com") == 0) { 372 comp->type = COMP_DELAYED; 373 } else if (strcmp(name, "zlib") == 0) { 374 comp->type = COMP_ZLIB; 375 } else if (strcmp(name, "none") == 0) { 376 comp->type = COMP_NONE; 377 } else { 378 fatal("unsupported comp %s", name); 379 } 380 comp->name = name; 381} 382 383static void 384choose_kex(Kex *k, char *client, char *server) 385{ 386 const struct kexalg *kexalg; 387 388 k->name = match_list(client, server, NULL); 389 if (k->name == NULL) 390 fatal("Unable to negotiate a key exchange method"); 391 if ((kexalg = kex_alg_by_name(k->name)) == NULL) 392 fatal("unsupported kex alg %s", k->name); 393 k->kex_type = kexalg->type; 394 k->hash_alg = kexalg->hash_alg; 395 k->ec_nid = kexalg->ec_nid; 396} 397 398static void 399choose_hostkeyalg(Kex *k, char *client, char *server) 400{ 401 char *hostkeyalg = match_list(client, server, NULL); 402 if (hostkeyalg == NULL) 403 fatal("no hostkey alg"); 404 k->hostkey_type = key_type_from_name(hostkeyalg); 405 if (k->hostkey_type == KEY_UNSPEC) 406 fatal("bad hostkey alg '%s'", hostkeyalg); 407 free(hostkeyalg); 408} 409 410static int 411proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) 412{ 413 static int check[] = { 414 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 415 }; 416 int *idx; 417 char *p; 418 419 for (idx = &check[0]; *idx != -1; idx++) { 420 if ((p = strchr(my[*idx], ',')) != NULL) 421 *p = '\0'; 422 if ((p = strchr(peer[*idx], ',')) != NULL) 423 *p = '\0'; 424 if (strcmp(my[*idx], peer[*idx]) != 0) { 425 debug2("proposal mismatch: my %s peer %s", 426 my[*idx], peer[*idx]); 427 return (0); 428 } 429 } 430 debug2("proposals match"); 431 return (1); 432} 433 434static void 435kex_choose_conf(Kex *kex) 436{ 437 Newkeys *newkeys; 438 char **my, **peer; 439 char **cprop, **sprop; 440 int nenc, nmac, ncomp; 441 u_int mode, ctos, need, authlen; 442 int first_kex_follows, type; 443 444 my = kex_buf2prop(&kex->my, NULL); 445 peer = kex_buf2prop(&kex->peer, &first_kex_follows); 446 447 if (kex->server) { 448 cprop=peer; 449 sprop=my; 450 } else { 451 cprop=my; 452 sprop=peer; 453 } 454 455 /* Check whether server offers roaming */ 456 if (!kex->server) { 457 char *roaming; 458 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); 459 if (roaming) { 460 kex->roaming = 1; 461 free(roaming); 462 } 463 } 464 465 /* Algorithm Negotiation */ 466 for (mode = 0; mode < MODE_MAX; mode++) { 467 newkeys = xcalloc(1, sizeof(*newkeys)); 468 kex->newkeys[mode] = newkeys; 469 ctos = (!kex->server && mode == MODE_OUT) || 470 (kex->server && mode == MODE_IN); 471 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; 472 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; 473 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; 474 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]); 475 /* ignore mac for authenticated encryption */ 476 authlen = cipher_authlen(newkeys->enc.cipher); 477 if (authlen == 0) 478 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]); 479 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); 480 debug("kex: %s %s %s %s", 481 ctos ? "client->server" : "server->client", 482 newkeys->enc.name, 483 authlen == 0 ? newkeys->mac.name : "<implicit>", 484 newkeys->comp.name); 485 } 486 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); 487 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], 488 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); 489 need = 0; 490 for (mode = 0; mode < MODE_MAX; mode++) { 491 newkeys = kex->newkeys[mode]; 492 if (need < newkeys->enc.key_len) 493 need = newkeys->enc.key_len; 494 if (need < newkeys->enc.block_size) 495 need = newkeys->enc.block_size; 496 if (need < newkeys->enc.iv_len) 497 need = newkeys->enc.iv_len; 498 if (need < newkeys->mac.key_len) 499 need = newkeys->mac.key_len; 500 } 501 /* XXX need runden? */ 502 kex->we_need = need; 503 504 /* ignore the next message if the proposals do not match */ 505 if (first_kex_follows && !proposals_match(my, peer) && 506 !(datafellows & SSH_BUG_FIRSTKEX)) { 507 type = packet_read(); 508 debug2("skipping next packet (type %u)", type); 509 } 510 511 kex_prop_free(my); 512 kex_prop_free(peer); 513} 514 515static u_char * 516derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, 517 BIGNUM *shared_secret) 518{ 519 Buffer b; 520 struct ssh_digest_ctx *hashctx; 521 char c = id; 522 u_int have; 523 size_t mdsz; 524 u_char *digest; 525 526 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0) 527 fatal("bad kex md size %zu", mdsz); 528 digest = xmalloc(roundup(need, mdsz)); 529 530 buffer_init(&b); 531 buffer_put_bignum2(&b, shared_secret); 532 533 /* K1 = HASH(K || H || "A" || session_id) */ 534 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 535 fatal("%s: ssh_digest_start failed", __func__); 536 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 537 ssh_digest_update(hashctx, hash, hashlen) != 0 || 538 ssh_digest_update(hashctx, &c, 1) != 0 || 539 ssh_digest_update(hashctx, kex->session_id, 540 kex->session_id_len) != 0) 541 fatal("%s: ssh_digest_update failed", __func__); 542 if (ssh_digest_final(hashctx, digest, mdsz) != 0) 543 fatal("%s: ssh_digest_final failed", __func__); 544 ssh_digest_free(hashctx); 545 546 /* 547 * expand key: 548 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) 549 * Key = K1 || K2 || ... || Kn 550 */ 551 for (have = mdsz; need > have; have += mdsz) { 552 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 553 fatal("%s: ssh_digest_start failed", __func__); 554 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 555 ssh_digest_update(hashctx, hash, hashlen) != 0 || 556 ssh_digest_update(hashctx, digest, have) != 0) 557 fatal("%s: ssh_digest_update failed", __func__); 558 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0) 559 fatal("%s: ssh_digest_final failed", __func__); 560 ssh_digest_free(hashctx); 561 } 562 buffer_free(&b); 563#ifdef DEBUG_KEX 564 fprintf(stderr, "key '%c'== ", c); 565 dump_digest("key", digest, need); 566#endif 567 return digest; 568} 569 570Newkeys *current_keys[MODE_MAX]; 571 572#define NKEYS 6 573void 574kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) 575{ 576 u_char *keys[NKEYS]; 577 u_int i, mode, ctos; 578 579 for (i = 0; i < NKEYS; i++) { 580 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, 581 shared_secret); 582 } 583 584 debug2("kex_derive_keys"); 585 for (mode = 0; mode < MODE_MAX; mode++) { 586 current_keys[mode] = kex->newkeys[mode]; 587 kex->newkeys[mode] = NULL; 588 ctos = (!kex->server && mode == MODE_OUT) || 589 (kex->server && mode == MODE_IN); 590 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; 591 current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; 592 current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; 593 } 594} 595 596Newkeys * 597kex_get_newkeys(int mode) 598{ 599 Newkeys *ret; 600 601 ret = current_keys[mode]; 602 current_keys[mode] = NULL; 603 return ret; 604} 605 606void 607derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, 608 u_int8_t cookie[8], u_int8_t id[16]) 609{ 610 u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH]; 611 int len; 612 struct ssh_digest_ctx *hashctx; 613 614 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) 615 fatal("%s: ssh_digest_start", __func__); 616 617 len = BN_num_bytes(host_modulus); 618 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 619 fatal("%s: bad host modulus (len %d)", __func__, len); 620 BN_bn2bin(host_modulus, nbuf); 621 if (ssh_digest_update(hashctx, nbuf, len) != 0) 622 fatal("%s: ssh_digest_update failed", __func__); 623 624 len = BN_num_bytes(server_modulus); 625 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 626 fatal("%s: bad server modulus (len %d)", __func__, len); 627 BN_bn2bin(server_modulus, nbuf); 628 if (ssh_digest_update(hashctx, nbuf, len) != 0 || 629 ssh_digest_update(hashctx, cookie, 8) != 0) 630 fatal("%s: ssh_digest_update failed", __func__); 631 if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) 632 fatal("%s: ssh_digest_final failed", __func__); 633 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5)); 634 635 memset(nbuf, 0, sizeof(nbuf)); 636 memset(obuf, 0, sizeof(obuf)); 637} 638 639#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 640void 641dump_digest(char *msg, u_char *digest, int len) 642{ 643 int i; 644 645 fprintf(stderr, "%s\n", msg); 646 for (i = 0; i < len; i++) { 647 fprintf(stderr, "%02x", digest[i]); 648 if (i%32 == 31) 649 fprintf(stderr, "\n"); 650 else if (i%8 == 7) 651 fprintf(stderr, " "); 652 } 653 fprintf(stderr, "\n"); 654} 655#endif 656