crypto/openssh/kex.c

   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 "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 #ifdef WITH_OPENSSL
  37 #include <openssl/crypto.h>
  38 #endif
  39
  40 #include "xmalloc.h"
  41 #include "ssh2.h"
  42 #include "buffer.h"
  43 #include "packet.h"
  44 #include "compat.h"
  45 #include "cipher.h"
  46 #include "key.h"
  47 #include "kex.h"
  48 #include "log.h"
  49 #include "mac.h"
  50 #include "match.h"
  51 #include "dispatch.h"
  52 #include "monitor.h"
  53 #include "roaming.h"
  54 #include "canohost.h"
  55 #include "digest.h"
  56
  57 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
  58 # if defined(HAVE_EVP_SHA256)
  59 # define evp_ssh_sha256 EVP_sha256
  60 # else
  61 extern const EVP_MD *evp_ssh_sha256(void);
  62 # endif
  63 #endif
  64
  65 /* prototype */
  66 static void kex_kexinit_finish(Kex *);
  67 static void kex_choose_conf(Kex *);
  68
  69 struct kexalg {
  70         char *name;
  71         int type;
  72         int ec_nid;
  73         int hash_alg;
  74 };
  75 static const struct kexalg kexalgs[] = {
  76 #ifdef WITH_OPENSSL
  77         { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
  78         { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
  79         { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
  80 #ifdef HAVE_EVP_SHA256
  81         { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
  82 #endif /* HAVE_EVP_SHA256 */
  83 #ifdef OPENSSL_HAS_ECC
  84         { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
  85             NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
  86         { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
  87             SSH_DIGEST_SHA384 },
  88 # ifdef OPENSSL_HAS_NISTP521
  89         { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
  90             SSH_DIGEST_SHA512 },
  91 # endif /* OPENSSL_HAS_NISTP521 */
  92 #endif /* OPENSSL_HAS_ECC */
  93         { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
  94 #endif /* WITH_OPENSSL */
  95 #ifdef HAVE_EVP_SHA256
  96         { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
  97 #endif /* HAVE_EVP_SHA256 */
  98         { NULL, -1, -1, -1},
  99 };
 100
 101 char *
 102 kex_alg_list(char sep)
 103 {
 104         char *ret = NULL;
 105         size_t nlen, rlen = 0;
 106         const struct kexalg *k;
 107
 108         for (k = kexalgs; k->name != NULL; k++) {
 109                 if (ret != NULL)
 110                         ret[rlen++] = sep;
 111                 nlen = strlen(k->name);
 112                 ret = xrealloc(ret, 1, rlen + nlen + 2);
 113                 memcpy(ret + rlen, k->name, nlen + 1);
 114                 rlen += nlen;
 115         }
 116         return ret;
 117 }
 118
 119 static const struct kexalg *
 120 kex_alg_by_name(const char *name)
 121 {
 122         const struct kexalg *k;
 123
 124         for (k = kexalgs; k->name != NULL; k++) {
 125                 if (strcmp(k->name, name) == 0)
 126                         return k;
 127         }
 128         return NULL;
 129 }
 130
 131 /* Validate KEX method name list */
 132 int
 133 kex_names_valid(const char *names)
 134 {
 135         char *s, *cp, *p;
 136
 137         if (names == NULL || strcmp(names, "") == 0)
 138                 return 0;
 139         s = cp = xstrdup(names);
 140         for ((p = strsep(&cp, ",")); p && *p != '\0';
 141             (p = strsep(&cp, ","))) {
 142                 if (kex_alg_by_name(p) == NULL) {
 143                         error("Unsupported KEX algorithm \"%.100s\"", p);
 144                         free(s);
 145                         return 0;
 146                 }
 147         }
 148         debug3("kex names ok: [%s]", names);
 149         free(s);
 150         return 1;
 151 }
 152
 153 /* put algorithm proposal into buffer */
 154 /* used in sshconnect.c as well as kex.c */
 155 void
 156 kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
 157 {
 158         u_int i;
 159
 160         buffer_clear(b);
 161         /*
 162          * add a dummy cookie, the cookie will be overwritten by
 163          * kex_send_kexinit(), each time a kexinit is set
 164          */
 165         for (i = 0; i < KEX_COOKIE_LEN; i++)
 166                 buffer_put_char(b, 0);
 167         for (i = 0; i < PROPOSAL_MAX; i++)
 168                 buffer_put_cstring(b, proposal[i]);
 169         buffer_put_char(b, 0);                  /* first_kex_packet_follows */
 170         buffer_put_int(b, 0);                   /* uint32 reserved */
 171 }
 172
 173 /* parse buffer and return algorithm proposal */
 174 static char **
 175 kex_buf2prop(Buffer *raw, int *first_kex_follows)
 176 {
 177         Buffer b;
 178         u_int i;
 179         char **proposal;
 180
 181         proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
 182
 183         buffer_init(&b);
 184         buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
 185         /* skip cookie */
 186         for (i = 0; i < KEX_COOKIE_LEN; i++)
 187                 buffer_get_char(&b);
 188         /* extract kex init proposal strings */
 189         for (i = 0; i < PROPOSAL_MAX; i++) {
 190                 proposal[i] = buffer_get_cstring(&b,NULL);
 191                 debug2("kex_parse_kexinit: %s", proposal[i]);
 192         }
 193         /* first kex follows / reserved */
 194         i = buffer_get_char(&b);
 195         if (first_kex_follows != NULL)
 196                 *first_kex_follows = i;
 197         debug2("kex_parse_kexinit: first_kex_follows %d ", i);
 198         i = buffer_get_int(&b);
 199         debug2("kex_parse_kexinit: reserved %u ", i);
 200         buffer_free(&b);
 201         return proposal;
 202 }
 203
 204 static void
 205 kex_prop_free(char **proposal)
 206 {
 207         u_int i;
 208
 209         for (i = 0; i < PROPOSAL_MAX; i++)
 210                 free(proposal[i]);
 211         free(proposal);
 212 }
 213
 214 /* ARGSUSED */
 215 static void
 216 kex_protocol_error(int type, u_int32_t seq, void *ctxt)
 217 {
 218         error("Hm, kex protocol error: type %d seq %u", type, seq);
 219 }
 220
 221 static void
 222 kex_reset_dispatch(void)
 223 {
 224         dispatch_range(SSH2_MSG_TRANSPORT_MIN,
 225             SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
 226         dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
 227 }
 228
 229 void
 230 kex_finish(Kex *kex)
 231 {
 232         kex_reset_dispatch();
 233
 234         packet_start(SSH2_MSG_NEWKEYS);
 235         packet_send();
 236         /* packet_write_wait(); */
 237         debug("SSH2_MSG_NEWKEYS sent");
 238
 239         debug("expecting SSH2_MSG_NEWKEYS");
 240         packet_read_expect(SSH2_MSG_NEWKEYS);
 241         packet_check_eom();
 242         debug("SSH2_MSG_NEWKEYS received");
 243
 244         kex->done = 1;
 245         buffer_clear(&kex->peer);
 246         /* buffer_clear(&kex->my); */
 247         kex->flags &= ~KEX_INIT_SENT;
 248         free(kex->name);
 249         kex->name = NULL;
 250 }
 251
 252 void
 253 kex_send_kexinit(Kex *kex)
 254 {
 255         u_int32_t rnd = 0;
 256         u_char *cookie;
 257         u_int i;
 258
 259         if (kex == NULL) {
 260                 error("kex_send_kexinit: no kex, cannot rekey");
 261                 return;
 262         }
 263         if (kex->flags & KEX_INIT_SENT) {
 264                 debug("KEX_INIT_SENT");
 265                 return;
 266         }
 267         kex->done = 0;
 268
 269         /* generate a random cookie */
 270         if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
 271                 fatal("kex_send_kexinit: kex proposal too short");
 272         cookie = buffer_ptr(&kex->my);
 273         for (i = 0; i < KEX_COOKIE_LEN; i++) {
 274                 if (i % 4 == 0)
 275                         rnd = arc4random();
 276                 cookie[i] = rnd;
 277                 rnd >>= 8;
 278         }
 279         packet_start(SSH2_MSG_KEXINIT);
 280         packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
 281         packet_send();
 282         debug("SSH2_MSG_KEXINIT sent");
 283         kex->flags |= KEX_INIT_SENT;
 284 }
 285
 286 /* ARGSUSED */
 287 void
 288 kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
 289 {
 290         char *ptr;
 291         u_int i, dlen;
 292         Kex *kex = (Kex *)ctxt;
 293
 294         debug("SSH2_MSG_KEXINIT received");
 295         if (kex == NULL)
 296                 fatal("kex_input_kexinit: no kex, cannot rekey");
 297
 298         ptr = packet_get_raw(&dlen);
 299         buffer_append(&kex->peer, ptr, dlen);
 300
 301         /* discard packet */
 302         for (i = 0; i < KEX_COOKIE_LEN; i++)
 303                 packet_get_char();
 304         for (i = 0; i < PROPOSAL_MAX; i++)
 305                 free(packet_get_string(NULL));
 306         /*
 307          * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
 308          * KEX method has the server move first, but a server might be using
 309          * a custom method or one that we otherwise don't support. We should
 310          * be prepared to remember first_kex_follows here so we can eat a
 311          * packet later.
 312          * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
 313          * for cases where the server *doesn't* go first. I guess we should
 314          * ignore it when it is set for these cases, which is what we do now.
 315          */
 316         (void) packet_get_char();       /* first_kex_follows */
 317         (void) packet_get_int();        /* reserved */
 318         packet_check_eom();
 319
 320         kex_kexinit_finish(kex);
 321 }
 322
 323 Kex *
 324 kex_setup(char *proposal[PROPOSAL_MAX])
 325 {
 326         Kex *kex;
 327
 328         kex = xcalloc(1, sizeof(*kex));
 329         buffer_init(&kex->peer);
 330         buffer_init(&kex->my);
 331         kex_prop2buf(&kex->my, proposal);
 332         kex->done = 0;
 333
 334         kex_send_kexinit(kex);                                  /* we start */
 335         kex_reset_dispatch();
 336
 337         return kex;
 338 }
 339
 340 static void
 341 kex_kexinit_finish(Kex *kex)
 342 {
 343         if (!(kex->flags & KEX_INIT_SENT))
 344                 kex_send_kexinit(kex);
 345
 346         kex_choose_conf(kex);
 347
 348         if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
 349             kex->kex[kex->kex_type] != NULL) {
 350                 (kex->kex[kex->kex_type])(kex);
 351         } else {
 352                 fatal("Unsupported key exchange %d", kex->kex_type);
 353         }
 354 }
 355
 356 static void
 357 choose_enc(Enc *enc, char *client, char *server)
 358 {
 359         char *name = match_list(client, server, NULL);
 360         if (name == NULL)
 361                 fatal("no matching cipher found: client %s server %s",
 362                     client, server);
 363         if ((enc->cipher = cipher_by_name(name)) == NULL)
 364                 fatal("matching cipher is not supported: %s", name);
 365         enc->name = name;
 366         enc->enabled = 0;
 367         enc->iv = NULL;
 368         enc->iv_len = cipher_ivlen(enc->cipher);
 369         enc->key = NULL;
 370         enc->key_len = cipher_keylen(enc->cipher);
 371         enc->block_size = cipher_blocksize(enc->cipher);
 372 }
 373
 374 static void
 375 choose_mac(Mac *mac, char *client, char *server)
 376 {
 377         char *name = match_list(client, server, NULL);
 378         if (name == NULL)
 379                 fatal("no matching mac found: client %s server %s",
 380                     client, server);
 381         if (mac_setup(mac, name) < 0)
 382                 fatal("unsupported mac %s", name);
 383         /* truncate the key */
 384         if (datafellows & SSH_BUG_HMAC)
 385                 mac->key_len = 16;
 386         mac->name = name;
 387         mac->key = NULL;
 388         mac->enabled = 0;
 389 }
 390
 391 static void
 392 choose_comp(Comp *comp, char *client, char *server)
 393 {
 394         char *name = match_list(client, server, NULL);
 395         if (name == NULL)
 396                 fatal("no matching comp found: client %s server %s", client, server);
 397         if (strcmp(name, "zlib@openssh.com") == 0) {
 398                 comp->type = COMP_DELAYED;
 399         } else if (strcmp(name, "zlib") == 0) {
 400                 comp->type = COMP_ZLIB;
 401         } else if (strcmp(name, "none") == 0) {
 402                 comp->type = COMP_NONE;
 403         } else {
 404                 fatal("unsupported comp %s", name);
 405         }
 406         comp->name = name;
 407 }
 408
 409 static void
 410 choose_kex(Kex *k, char *client, char *server)
 411 {
 412         const struct kexalg *kexalg;
 413
 414         k->name = match_list(client, server, NULL);
 415         if (k->name == NULL)
 416                 fatal("Unable to negotiate a key exchange method");
 417         if ((kexalg = kex_alg_by_name(k->name)) == NULL)
 418                 fatal("unsupported kex alg %s", k->name);
 419         k->kex_type = kexalg->type;
 420         k->hash_alg = kexalg->hash_alg;
 421         k->ec_nid = kexalg->ec_nid;
 422 }
 423
 424 static void
 425 choose_hostkeyalg(Kex *k, char *client, char *server)
 426 {
 427         char *hostkeyalg = match_list(client, server, NULL);
 428         if (hostkeyalg == NULL)
 429                 fatal("no hostkey alg");
 430         k->hostkey_type = key_type_from_name(hostkeyalg);
 431         if (k->hostkey_type == KEY_UNSPEC)
 432                 fatal("bad hostkey alg '%s'", hostkeyalg);
 433         free(hostkeyalg);
 434 }
 435
 436 static int
 437 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
 438 {
 439         static int check[] = {
 440                 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
 441         };
 442         int *idx;
 443         char *p;
 444
 445         for (idx = &check[0]; *idx != -1; idx++) {
 446                 if ((p = strchr(my[*idx], ',')) != NULL)
 447                         *p = '\0';
 448                 if ((p = strchr(peer[*idx], ',')) != NULL)
 449                         *p = '\0';
 450                 if (strcmp(my[*idx], peer[*idx]) != 0) {
 451                         debug2("proposal mismatch: my %s peer %s",
 452                             my[*idx], peer[*idx]);
 453                         return (0);
 454                 }
 455         }
 456         debug2("proposals match");
 457         return (1);
 458 }
 459
 460 static void
 461 kex_choose_conf(Kex *kex)
 462 {
 463         Newkeys *newkeys;
 464         char **my, **peer;
 465         char **cprop, **sprop;
 466         int nenc, nmac, ncomp;
 467         u_int mode, ctos, need, dh_need, authlen;
 468         int first_kex_follows, type;
 469         int log_flag = 0;
 470         int auth_flag;
 471
 472         auth_flag = packet_authentication_state();
 473         debug ("AUTH STATE IS %d", auth_flag);
 474
 475         my   = kex_buf2prop(&kex->my, NULL);
 476         peer = kex_buf2prop(&kex->peer, &first_kex_follows);
 477
 478         if (kex->server) {
 479                 cprop=peer;
 480                 sprop=my;
 481         } else {
 482                 cprop=my;
 483                 sprop=peer;
 484         }
 485
 486         /* Check whether server offers roaming */
 487         if (!kex->server) {
 488                 char *roaming;
 489                 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
 490                 if (roaming) {
 491                         kex->roaming = 1;
 492                         free(roaming);
 493                 }
 494         }
 495
 496         /* Algorithm Negotiation */
 497         for (mode = 0; mode < MODE_MAX; mode++) {
 498                 newkeys = xcalloc(1, sizeof(*newkeys));
 499                 kex->newkeys[mode] = newkeys;
 500                 ctos = (!kex->server && mode == MODE_OUT) ||
 501                     (kex->server && mode == MODE_IN);
 502                 nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
 503                 nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
 504                 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
 505                 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
 506                 /* ignore mac for authenticated encryption */
 507                 authlen = cipher_authlen(newkeys->enc.cipher);
 508                 if (authlen == 0)
 509                         choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
 510                 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
 511                 debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name);
 512                 if (strcmp(newkeys->enc.name, "none") == 0) {
 513                         debug("Requesting NONE. Authflag is %d", auth_flag);
 514                         if (auth_flag == 1) {
 515                                 debug("None requested post authentication.");
 516                         } else {
 517                                 fatal("Pre-authentication none cipher requests are not allowed.");
 518                         }
 519                 }
 520                 debug("kex: %s %s %s %s",
 521                     ctos ? "client->server" : "server->client",
 522                     newkeys->enc.name,
 523                     authlen == 0 ? newkeys->mac.name : "<implicit>",
 524                     newkeys->comp.name);
 525                 /* client starts withctos = 0 && log flag = 0 and no log*/
 526                 /* 2nd client pass ctos=1 and flag = 1 so no log*/
 527                 /* server starts with ctos =1 && log_flag = 0 so log */
 528                 /* 2nd sever pass ctos = 1 && log flag = 1 so no log*/
 529                 /* -cjr*/
 530                 if (ctos && !log_flag) {
 531                         logit("SSH: Server;Ltype: Kex;Remote: %s-%d;Enc: %s;MAC: %s;Comp: %s",
 532                               get_remote_ipaddr(),
 533                               get_remote_port(),
 534                               newkeys->enc.name,
 535                               newkeys->mac.name,
 536                               newkeys->comp.name);
 537                 }
 538                 log_flag = 1;
 539         }
 540         choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
 541         choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
 542             sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
 543         need = dh_need = 0;
 544         for (mode = 0; mode < MODE_MAX; mode++) {
 545                 newkeys = kex->newkeys[mode];
 546                 need = MAX(need, newkeys->enc.key_len);
 547                 need = MAX(need, newkeys->enc.block_size);
 548                 need = MAX(need, newkeys->enc.iv_len);
 549                 need = MAX(need, newkeys->mac.key_len);
 550                 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher));
 551                 dh_need = MAX(dh_need, newkeys->enc.block_size);
 552                 dh_need = MAX(dh_need, newkeys->enc.iv_len);
 553                 dh_need = MAX(dh_need, newkeys->mac.key_len);
 554         }
 555         /* XXX need runden? */
 556         kex->we_need = need;
 557         kex->dh_need = dh_need;
 558
 559         /* ignore the next message if the proposals do not match */
 560         if (first_kex_follows && !proposals_match(my, peer) &&
 561             !(datafellows & SSH_BUG_FIRSTKEX)) {
 562                 type = packet_read();
 563                 debug2("skipping next packet (type %u)", type);
 564         }
 565
 566         kex_prop_free(my);
 567         kex_prop_free(peer);
 568 }
 569
 570 static u_char *
 571 derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
 572     const u_char *shared_secret, u_int slen)
 573 {
 574         Buffer b;
 575         struct ssh_digest_ctx *hashctx;
 576         char c = id;
 577         u_int have;
 578         size_t mdsz;
 579         u_char *digest;
 580
 581         if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
 582                 fatal("bad kex md size %zu", mdsz);
 583         digest = xmalloc(roundup(need, mdsz));
 584
 585         buffer_init(&b);
 586         buffer_append(&b, shared_secret, slen);
 587
 588         /* K1 = HASH(K || H || "A" || session_id) */
 589         if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
 590                 fatal("%s: ssh_digest_start failed", __func__);
 591         if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
 592             ssh_digest_update(hashctx, hash, hashlen) != 0 ||
 593             ssh_digest_update(hashctx, &c, 1) != 0 ||
 594             ssh_digest_update(hashctx, kex->session_id,
 595             kex->session_id_len) != 0)
 596                 fatal("%s: ssh_digest_update failed", __func__);
 597         if (ssh_digest_final(hashctx, digest, mdsz) != 0)
 598                 fatal("%s: ssh_digest_final failed", __func__);
 599         ssh_digest_free(hashctx);
 600
 601         /*
 602          * expand key:
 603          * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
 604          * Key = K1 || K2 || ... || Kn
 605          */
 606         for (have = mdsz; need > have; have += mdsz) {
 607                 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
 608                         fatal("%s: ssh_digest_start failed", __func__);
 609                 if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
 610                     ssh_digest_update(hashctx, hash, hashlen) != 0 ||
 611                     ssh_digest_update(hashctx, digest, have) != 0)
 612                         fatal("%s: ssh_digest_update failed", __func__);
 613                 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0)
 614                         fatal("%s: ssh_digest_final failed", __func__);
 615                 ssh_digest_free(hashctx);
 616         }
 617         buffer_free(&b);
 618 #ifdef DEBUG_KEX
 619         fprintf(stderr, "key '%c'== ", c);
 620         dump_digest("key", digest, need);
 621 #endif
 622         return digest;
 623 }
 624
 625 Newkeys *current_keys[MODE_MAX];
 626
 627 #define NKEYS   6
 628 void
 629 kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen,
 630     const u_char *shared_secret, u_int slen)
 631 {
 632         u_char *keys[NKEYS];
 633         u_int i, mode, ctos;
 634
 635         for (i = 0; i < NKEYS; i++) {
 636                 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
 637                     shared_secret, slen);
 638         }
 639
 640         debug2("kex_derive_keys");
 641         for (mode = 0; mode < MODE_MAX; mode++) {
 642                 current_keys[mode] = kex->newkeys[mode];
 643                 kex->newkeys[mode] = NULL;
 644                 ctos = (!kex->server && mode == MODE_OUT) ||
 645                     (kex->server && mode == MODE_IN);
 646                 current_keys[mode]->enc.iv  = keys[ctos ? 0 : 1];
 647                 current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
 648                 current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
 649         }
 650 }
 651
 652 #ifdef WITH_OPENSSL
 653 void
 654 kex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret)
 655 {
 656         Buffer shared_secret;
 657
 658         buffer_init(&shared_secret);
 659         buffer_put_bignum2(&shared_secret, secret);
 660         kex_derive_keys(kex, hash, hashlen,
 661             buffer_ptr(&shared_secret), buffer_len(&shared_secret));
 662         buffer_free(&shared_secret);
 663 }
 664 #endif
 665
 666 Newkeys *
 667 kex_get_newkeys(int mode)
 668 {
 669         Newkeys *ret;
 670
 671         ret = current_keys[mode];
 672         current_keys[mode] = NULL;
 673         return ret;
 674 }
 675
 676 #ifdef WITH_SSH1
 677 void
 678 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
 679     u_int8_t cookie[8], u_int8_t id[16])
 680 {
 681         u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH];
 682         int len;
 683         struct ssh_digest_ctx *hashctx;
 684
 685         if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL)
 686                 fatal("%s: ssh_digest_start", __func__);
 687
 688         len = BN_num_bytes(host_modulus);
 689         if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
 690                 fatal("%s: bad host modulus (len %d)", __func__, len);
 691         BN_bn2bin(host_modulus, nbuf);
 692         if (ssh_digest_update(hashctx, nbuf, len) != 0)
 693                 fatal("%s: ssh_digest_update failed", __func__);
 694
 695         len = BN_num_bytes(server_modulus);
 696         if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
 697                 fatal("%s: bad server modulus (len %d)", __func__, len);
 698         BN_bn2bin(server_modulus, nbuf);
 699         if (ssh_digest_update(hashctx, nbuf, len) != 0 ||
 700             ssh_digest_update(hashctx, cookie, 8) != 0)
 701                 fatal("%s: ssh_digest_update failed", __func__);
 702         if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0)
 703                 fatal("%s: ssh_digest_final failed", __func__);
 704         memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5));
 705
 706         explicit_bzero(nbuf, sizeof(nbuf));
 707         explicit_bzero(obuf, sizeof(obuf));
 708 }
 709 #endif
 710
 711 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
 712 void
 713 dump_digest(char *msg, u_char *digest, int len)
 714 {
 715         int i;
 716
 717         fprintf(stderr, "%s\n", msg);
 718         for (i = 0; i < len; i++) {
 719                 fprintf(stderr, "%02x", digest[i]);
 720                 if (i%32 == 31)
 721                         fprintf(stderr, "\n");
 722                 else if (i%8 == 7)
 723                         fprintf(stderr, " ");
 724         }
 725         fprintf(stderr, "\n");
 726 }
 727 #endif