1 /* $OpenBSD: kex.c,v 1.88 2013/01/08 18:49:04 markus Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #include <sys/param.h> 30 31 #include <signal.h> 32 #include <stdarg.h> 33 #include <stdio.h> 34 #include <stdlib.h> 35 #include <string.h> 36 37 #include <openssl/crypto.h> 38 39 #include "xmalloc.h" 40 #include "ssh2.h" 41 #include "buffer.h" 42 #include "packet.h" 43 #include "compat.h" 44 #include "cipher.h" 45 #include "key.h" 46 #include "kex.h" 47 #include "log.h" 48 #include "mac.h" 49 #include "match.h" 50 #include "dispatch.h" 51 #include "monitor.h" 52 #include "roaming.h" 53 54 #if OPENSSL_VERSION_NUMBER >= 0x00907000L 55 # if defined(HAVE_EVP_SHA256) 56 # define evp_ssh_sha256 EVP_sha256 57 # else 58 extern const EVP_MD *evp_ssh_sha256(void); 59 # endif 60 #endif 61 62 /* prototype */ 63 static void kex_kexinit_finish(Kex *); 64 static void kex_choose_conf(Kex *); 65 66 /* Validate KEX method name list */ 67 int 68 kex_names_valid(const char *names) 69 { 70 char *s, *cp, *p; 71 72 if (names == NULL || strcmp(names, "") == 0) 73 return 0; 74 s = cp = xstrdup(names); 75 for ((p = strsep(&cp, ",")); p && *p != '\0'; 76 (p = strsep(&cp, ","))) { 77 if (strcmp(p, KEX_DHGEX_SHA256) != 0 && 78 strcmp(p, KEX_DHGEX_SHA1) != 0 && 79 strcmp(p, KEX_DH14) != 0 && 80 strcmp(p, KEX_DH1) != 0 && 81 (strncmp(p, KEX_ECDH_SHA2_STEM, 82 sizeof(KEX_ECDH_SHA2_STEM) - 1) != 0 || 83 kex_ecdh_name_to_nid(p) == -1)) { 84 error("Unsupported KEX algorithm \"%.100s\"", p); 85 xfree(s); 86 return 0; 87 } 88 } 89 debug3("kex names ok: [%s]", names); 90 xfree(s); 91 return 1; 92 } 93 94 /* put algorithm proposal into buffer. */ 95 #ifndef NONE_CIPHER_ENABLED 96 static void 97 #else 98 /* Also used in sshconnect2.c. */ 99 void 100 #endif 101 kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) 102 { 103 u_int i; 104 105 buffer_clear(b); 106 /* 107 * add a dummy cookie, the cookie will be overwritten by 108 * kex_send_kexinit(), each time a kexinit is set 109 */ 110 for (i = 0; i < KEX_COOKIE_LEN; i++) 111 buffer_put_char(b, 0); 112 for (i = 0; i < PROPOSAL_MAX; i++) 113 buffer_put_cstring(b, proposal[i]); 114 buffer_put_char(b, 0); /* first_kex_packet_follows */ 115 buffer_put_int(b, 0); /* uint32 reserved */ 116 } 117 118 /* parse buffer and return algorithm proposal */ 119 static char ** 120 kex_buf2prop(Buffer *raw, int *first_kex_follows) 121 { 122 Buffer b; 123 u_int i; 124 char **proposal; 125 126 proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); 127 128 buffer_init(&b); 129 buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); 130 /* skip cookie */ 131 for (i = 0; i < KEX_COOKIE_LEN; i++) 132 buffer_get_char(&b); 133 /* extract kex init proposal strings */ 134 for (i = 0; i < PROPOSAL_MAX; i++) { 135 proposal[i] = buffer_get_cstring(&b,NULL); 136 debug2("kex_parse_kexinit: %s", proposal[i]); 137 } 138 /* first kex follows / reserved */ 139 i = buffer_get_char(&b); 140 if (first_kex_follows != NULL) 141 *first_kex_follows = i; 142 debug2("kex_parse_kexinit: first_kex_follows %d ", i); 143 i = buffer_get_int(&b); 144 debug2("kex_parse_kexinit: reserved %u ", i); 145 buffer_free(&b); 146 return proposal; 147 } 148 149 static void 150 kex_prop_free(char **proposal) 151 { 152 u_int i; 153 154 for (i = 0; i < PROPOSAL_MAX; i++) 155 xfree(proposal[i]); 156 xfree(proposal); 157 } 158 159 /* ARGSUSED */ 160 static void 161 kex_protocol_error(int type, u_int32_t seq, void *ctxt) 162 { 163 error("Hm, kex protocol error: type %d seq %u", type, seq); 164 } 165 166 static void 167 kex_reset_dispatch(void) 168 { 169 dispatch_range(SSH2_MSG_TRANSPORT_MIN, 170 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); 171 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 172 } 173 174 void 175 kex_finish(Kex *kex) 176 { 177 kex_reset_dispatch(); 178 179 packet_start(SSH2_MSG_NEWKEYS); 180 packet_send(); 181 /* packet_write_wait(); */ 182 debug("SSH2_MSG_NEWKEYS sent"); 183 184 debug("expecting SSH2_MSG_NEWKEYS"); 185 packet_read_expect(SSH2_MSG_NEWKEYS); 186 packet_check_eom(); 187 debug("SSH2_MSG_NEWKEYS received"); 188 189 kex->done = 1; 190 buffer_clear(&kex->peer); 191 /* buffer_clear(&kex->my); */ 192 kex->flags &= ~KEX_INIT_SENT; 193 xfree(kex->name); 194 kex->name = NULL; 195 } 196 197 void 198 kex_send_kexinit(Kex *kex) 199 { 200 u_int32_t rnd = 0; 201 u_char *cookie; 202 u_int i; 203 204 if (kex == NULL) { 205 error("kex_send_kexinit: no kex, cannot rekey"); 206 return; 207 } 208 if (kex->flags & KEX_INIT_SENT) { 209 debug("KEX_INIT_SENT"); 210 return; 211 } 212 kex->done = 0; 213 214 /* generate a random cookie */ 215 if (buffer_len(&kex->my) < KEX_COOKIE_LEN) 216 fatal("kex_send_kexinit: kex proposal too short"); 217 cookie = buffer_ptr(&kex->my); 218 for (i = 0; i < KEX_COOKIE_LEN; i++) { 219 if (i % 4 == 0) 220 rnd = arc4random(); 221 cookie[i] = rnd; 222 rnd >>= 8; 223 } 224 packet_start(SSH2_MSG_KEXINIT); 225 packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); 226 packet_send(); 227 debug("SSH2_MSG_KEXINIT sent"); 228 kex->flags |= KEX_INIT_SENT; 229 } 230 231 /* ARGSUSED */ 232 void 233 kex_input_kexinit(int type, u_int32_t seq, void *ctxt) 234 { 235 char *ptr; 236 u_int i, dlen; 237 Kex *kex = (Kex *)ctxt; 238 239 debug("SSH2_MSG_KEXINIT received"); 240 if (kex == NULL) 241 fatal("kex_input_kexinit: no kex, cannot rekey"); 242 243 ptr = packet_get_raw(&dlen); 244 buffer_append(&kex->peer, ptr, dlen); 245 246 /* discard packet */ 247 for (i = 0; i < KEX_COOKIE_LEN; i++) 248 packet_get_char(); 249 for (i = 0; i < PROPOSAL_MAX; i++) 250 xfree(packet_get_string(NULL)); 251 /* 252 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported 253 * KEX method has the server move first, but a server might be using 254 * a custom method or one that we otherwise don't support. We should 255 * be prepared to remember first_kex_follows here so we can eat a 256 * packet later. 257 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means 258 * for cases where the server *doesn't* go first. I guess we should 259 * ignore it when it is set for these cases, which is what we do now. 260 */ 261 (void) packet_get_char(); /* first_kex_follows */ 262 (void) packet_get_int(); /* reserved */ 263 packet_check_eom(); 264 265 kex_kexinit_finish(kex); 266 } 267 268 Kex * 269 kex_setup(char *proposal[PROPOSAL_MAX]) 270 { 271 Kex *kex; 272 273 kex = xcalloc(1, sizeof(*kex)); 274 buffer_init(&kex->peer); 275 buffer_init(&kex->my); 276 kex_prop2buf(&kex->my, proposal); 277 kex->done = 0; 278 279 kex_send_kexinit(kex); /* we start */ 280 kex_reset_dispatch(); 281 282 return kex; 283 } 284 285 static void 286 kex_kexinit_finish(Kex *kex) 287 { 288 if (!(kex->flags & KEX_INIT_SENT)) 289 kex_send_kexinit(kex); 290 291 kex_choose_conf(kex); 292 293 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && 294 kex->kex[kex->kex_type] != NULL) { 295 (kex->kex[kex->kex_type])(kex); 296 } else { 297 fatal("Unsupported key exchange %d", kex->kex_type); 298 } 299 } 300 301 static void 302 choose_enc(Enc *enc, char *client, char *server) 303 { 304 char *name = match_list(client, server, NULL); 305 if (name == NULL) 306 fatal("no matching cipher found: client %s server %s", 307 client, server); 308 if ((enc->cipher = cipher_by_name(name)) == NULL) 309 fatal("matching cipher is not supported: %s", name); 310 enc->name = name; 311 enc->enabled = 0; 312 enc->iv = NULL; 313 enc->iv_len = cipher_ivlen(enc->cipher); 314 enc->key = NULL; 315 enc->key_len = cipher_keylen(enc->cipher); 316 enc->block_size = cipher_blocksize(enc->cipher); 317 } 318 319 static void 320 choose_mac(Mac *mac, char *client, char *server) 321 { 322 char *name = match_list(client, server, NULL); 323 if (name == NULL) 324 fatal("no matching mac found: client %s server %s", 325 client, server); 326 if (mac_setup(mac, name) < 0) 327 fatal("unsupported mac %s", name); 328 /* truncate the key */ 329 if (datafellows & SSH_BUG_HMAC) 330 mac->key_len = 16; 331 mac->name = name; 332 mac->key = NULL; 333 mac->enabled = 0; 334 } 335 336 static void 337 choose_comp(Comp *comp, char *client, char *server) 338 { 339 char *name = match_list(client, server, NULL); 340 if (name == NULL) 341 fatal("no matching comp found: client %s server %s", client, server); 342 if (strcmp(name, "zlib@openssh.com") == 0) { 343 comp->type = COMP_DELAYED; 344 } else if (strcmp(name, "zlib") == 0) { 345 comp->type = COMP_ZLIB; 346 } else if (strcmp(name, "none") == 0) { 347 comp->type = COMP_NONE; 348 } else { 349 fatal("unsupported comp %s", name); 350 } 351 comp->name = name; 352 } 353 354 static void 355 choose_kex(Kex *k, char *client, char *server) 356 { 357 k->name = match_list(client, server, NULL); 358 if (k->name == NULL) 359 fatal("Unable to negotiate a key exchange method"); 360 if (strcmp(k->name, KEX_DH1) == 0) { 361 k->kex_type = KEX_DH_GRP1_SHA1; 362 k->evp_md = EVP_sha1(); 363 } else if (strcmp(k->name, KEX_DH14) == 0) { 364 k->kex_type = KEX_DH_GRP14_SHA1; 365 k->evp_md = EVP_sha1(); 366 } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { 367 k->kex_type = KEX_DH_GEX_SHA1; 368 k->evp_md = EVP_sha1(); 369 #if OPENSSL_VERSION_NUMBER >= 0x00907000L 370 } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { 371 k->kex_type = KEX_DH_GEX_SHA256; 372 k->evp_md = evp_ssh_sha256(); 373 } else if (strncmp(k->name, KEX_ECDH_SHA2_STEM, 374 sizeof(KEX_ECDH_SHA2_STEM) - 1) == 0) { 375 k->kex_type = KEX_ECDH_SHA2; 376 k->evp_md = kex_ecdh_name_to_evpmd(k->name); 377 #endif 378 } else 379 fatal("bad kex alg %s", k->name); 380 } 381 382 static void 383 choose_hostkeyalg(Kex *k, char *client, char *server) 384 { 385 char *hostkeyalg = match_list(client, server, NULL); 386 if (hostkeyalg == NULL) 387 fatal("no hostkey alg"); 388 k->hostkey_type = key_type_from_name(hostkeyalg); 389 if (k->hostkey_type == KEY_UNSPEC) 390 fatal("bad hostkey alg '%s'", hostkeyalg); 391 xfree(hostkeyalg); 392 } 393 394 static int 395 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) 396 { 397 static int check[] = { 398 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 399 }; 400 int *idx; 401 char *p; 402 403 for (idx = &check[0]; *idx != -1; idx++) { 404 if ((p = strchr(my[*idx], ',')) != NULL) 405 *p = '\0'; 406 if ((p = strchr(peer[*idx], ',')) != NULL) 407 *p = '\0'; 408 if (strcmp(my[*idx], peer[*idx]) != 0) { 409 debug2("proposal mismatch: my %s peer %s", 410 my[*idx], peer[*idx]); 411 return (0); 412 } 413 } 414 debug2("proposals match"); 415 return (1); 416 } 417 418 static void 419 kex_choose_conf(Kex *kex) 420 { 421 Newkeys *newkeys; 422 char **my, **peer; 423 char **cprop, **sprop; 424 int nenc, nmac, ncomp; 425 u_int mode, ctos, need, authlen; 426 int first_kex_follows, type; 427 #ifdef NONE_CIPHER_ENABLED 428 int auth_flag; 429 #endif 430 431 my = kex_buf2prop(&kex->my, NULL); 432 peer = kex_buf2prop(&kex->peer, &first_kex_follows); 433 434 if (kex->server) { 435 cprop=peer; 436 sprop=my; 437 } else { 438 cprop=my; 439 sprop=peer; 440 } 441 442 /* Check whether server offers roaming */ 443 if (!kex->server) { 444 char *roaming; 445 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); 446 if (roaming) { 447 kex->roaming = 1; 448 xfree(roaming); 449 } 450 } 451 452 /* Algorithm Negotiation */ 453 #ifdef NONE_CIPHER_ENABLED 454 auth_flag = packet_get_authentication_state(); 455 debug ("AUTH STATE is %d", auth_flag); 456 #endif 457 for (mode = 0; mode < MODE_MAX; mode++) { 458 newkeys = xcalloc(1, sizeof(*newkeys)); 459 kex->newkeys[mode] = newkeys; 460 ctos = (!kex->server && mode == MODE_OUT) || 461 (kex->server && mode == MODE_IN); 462 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; 463 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; 464 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; 465 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]); 466 /* ignore mac for authenticated encryption */ 467 authlen = cipher_authlen(newkeys->enc.cipher); 468 if (authlen == 0) 469 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]); 470 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); 471 #ifdef NONE_CIPHER_ENABLED 472 debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name); 473 if (strcmp(newkeys->enc.name, "none") == 0) { 474 debug("Requesting NONE. Authflag is %d", auth_flag); 475 if (auth_flag == 1) 476 debug("None requested post authentication."); 477 else 478 fatal("Pre-authentication none cipher requests " 479 "are not allowed."); 480 } 481 #endif 482 debug("kex: %s %s %s %s", 483 ctos ? "client->server" : "server->client", 484 newkeys->enc.name, 485 authlen == 0 ? newkeys->mac.name : "<implicit>", 486 newkeys->comp.name); 487 } 488 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); 489 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], 490 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); 491 need = 0; 492 for (mode = 0; mode < MODE_MAX; mode++) { 493 newkeys = kex->newkeys[mode]; 494 if (need < newkeys->enc.key_len) 495 need = newkeys->enc.key_len; 496 if (need < newkeys->enc.block_size) 497 need = newkeys->enc.block_size; 498 if (need < newkeys->enc.iv_len) 499 need = newkeys->enc.iv_len; 500 if (need < newkeys->mac.key_len) 501 need = newkeys->mac.key_len; 502 } 503 /* XXX need runden? */ 504 kex->we_need = need; 505 506 /* ignore the next message if the proposals do not match */ 507 if (first_kex_follows && !proposals_match(my, peer) && 508 !(datafellows & SSH_BUG_FIRSTKEX)) { 509 type = packet_read(); 510 debug2("skipping next packet (type %u)", type); 511 } 512 513 kex_prop_free(my); 514 kex_prop_free(peer); 515 } 516 517 static u_char * 518 derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, 519 BIGNUM *shared_secret) 520 { 521 Buffer b; 522 EVP_MD_CTX md; 523 char c = id; 524 u_int have; 525 int mdsz; 526 u_char *digest; 527 528 if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) 529 fatal("bad kex md size %d", mdsz); 530 digest = xmalloc(roundup(need, mdsz)); 531 532 buffer_init(&b); 533 buffer_put_bignum2(&b, shared_secret); 534 535 /* K1 = HASH(K || H || "A" || session_id) */ 536 EVP_DigestInit(&md, kex->evp_md); 537 if (!(datafellows & SSH_BUG_DERIVEKEY)) 538 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); 539 EVP_DigestUpdate(&md, hash, hashlen); 540 EVP_DigestUpdate(&md, &c, 1); 541 EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); 542 EVP_DigestFinal(&md, digest, NULL); 543 544 /* 545 * expand key: 546 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) 547 * Key = K1 || K2 || ... || Kn 548 */ 549 for (have = mdsz; need > have; have += mdsz) { 550 EVP_DigestInit(&md, kex->evp_md); 551 if (!(datafellows & SSH_BUG_DERIVEKEY)) 552 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); 553 EVP_DigestUpdate(&md, hash, hashlen); 554 EVP_DigestUpdate(&md, digest, have); 555 EVP_DigestFinal(&md, digest + have, NULL); 556 } 557 buffer_free(&b); 558 #ifdef DEBUG_KEX 559 fprintf(stderr, "key '%c'== ", c); 560 dump_digest("key", digest, need); 561 #endif 562 return digest; 563 } 564 565 Newkeys *current_keys[MODE_MAX]; 566 567 #define NKEYS 6 568 void 569 kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) 570 { 571 u_char *keys[NKEYS]; 572 u_int i, mode, ctos; 573 574 for (i = 0; i < NKEYS; i++) { 575 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, 576 shared_secret); 577 } 578 579 debug2("kex_derive_keys"); 580 for (mode = 0; mode < MODE_MAX; mode++) { 581 current_keys[mode] = kex->newkeys[mode]; 582 kex->newkeys[mode] = NULL; 583 ctos = (!kex->server && mode == MODE_OUT) || 584 (kex->server && mode == MODE_IN); 585 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; 586 current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; 587 current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; 588 } 589 } 590 591 Newkeys * 592 kex_get_newkeys(int mode) 593 { 594 Newkeys *ret; 595 596 ret = current_keys[mode]; 597 current_keys[mode] = NULL; 598 return ret; 599 } 600 601 void 602 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, 603 u_int8_t cookie[8], u_int8_t id[16]) 604 { 605 const EVP_MD *evp_md = EVP_md5(); 606 EVP_MD_CTX md; 607 u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; 608 int len; 609 610 EVP_DigestInit(&md, evp_md); 611 612 len = BN_num_bytes(host_modulus); 613 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 614 fatal("%s: bad host modulus (len %d)", __func__, len); 615 BN_bn2bin(host_modulus, nbuf); 616 EVP_DigestUpdate(&md, nbuf, len); 617 618 len = BN_num_bytes(server_modulus); 619 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 620 fatal("%s: bad server modulus (len %d)", __func__, len); 621 BN_bn2bin(server_modulus, nbuf); 622 EVP_DigestUpdate(&md, nbuf, len); 623 624 EVP_DigestUpdate(&md, cookie, 8); 625 626 EVP_DigestFinal(&md, obuf, NULL); 627 memcpy(id, obuf, 16); 628 629 memset(nbuf, 0, sizeof(nbuf)); 630 memset(obuf, 0, sizeof(obuf)); 631 memset(&md, 0, sizeof(md)); 632 } 633 634 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 635 void 636 dump_digest(char *msg, u_char *digest, int len) 637 { 638 int i; 639 640 fprintf(stderr, "%s\n", msg); 641 for (i = 0; i < len; i++) { 642 fprintf(stderr, "%02x", digest[i]); 643 if (i%32 == 31) 644 fprintf(stderr, "\n"); 645 else if (i%8 == 7) 646 fprintf(stderr, " "); 647 } 648 fprintf(stderr, "\n"); 649 } 650 #endif 651