1 /* $OpenBSD: kex.c,v 1.134 2017/06/13 12:13:59 djm Exp $ */
3 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
36 #include <openssl/crypto.h>
37 #include <openssl/dh.h>
58 static int kex_choose_conf(struct ssh *);
59 static int kex_input_newkeys(int, u_int32_t, struct ssh *);
61 static const char *proposal_names[PROPOSAL_MAX] = {
63 "host key algorithms",
80 static const struct kexalg kexalgs[] = {
82 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
83 { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
84 { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
85 { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
86 { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
87 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
88 #ifdef HAVE_EVP_SHA256
89 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
90 #endif /* HAVE_EVP_SHA256 */
91 #ifdef OPENSSL_HAS_ECC
92 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
93 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
94 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
96 # ifdef OPENSSL_HAS_NISTP521
97 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
99 # endif /* OPENSSL_HAS_NISTP521 */
100 #endif /* OPENSSL_HAS_ECC */
101 #endif /* WITH_OPENSSL */
102 #if defined(HAVE_EVP_SHA256) || !defined(WITH_OPENSSL)
103 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
104 { KEX_CURVE25519_SHA256_OLD, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
105 #endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
110 kex_alg_list(char sep)
112 char *ret = NULL, *tmp;
113 size_t nlen, rlen = 0;
114 const struct kexalg *k;
116 for (k = kexalgs; k->name != NULL; k++) {
119 nlen = strlen(k->name);
120 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
125 memcpy(ret + rlen, k->name, nlen + 1);
131 static const struct kexalg *
132 kex_alg_by_name(const char *name)
134 const struct kexalg *k;
136 for (k = kexalgs; k->name != NULL; k++) {
137 if (strcmp(k->name, name) == 0)
143 /* Validate KEX method name list */
145 kex_names_valid(const char *names)
149 if (names == NULL || strcmp(names, "") == 0)
151 if ((s = cp = strdup(names)) == NULL)
153 for ((p = strsep(&cp, ",")); p && *p != '\0';
154 (p = strsep(&cp, ","))) {
155 if (kex_alg_by_name(p) == NULL) {
156 error("Unsupported KEX algorithm \"%.100s\"", p);
161 debug3("kex names ok: [%s]", names);
167 * Concatenate algorithm names, avoiding duplicates in the process.
168 * Caller must free returned string.
171 kex_names_cat(const char *a, const char *b)
173 char *ret = NULL, *tmp = NULL, *cp, *p, *m;
176 if (a == NULL || *a == '\0')
178 if (b == NULL || *b == '\0')
180 if (strlen(b) > 1024*1024)
182 len = strlen(a) + strlen(b) + 2;
183 if ((tmp = cp = strdup(b)) == NULL ||
184 (ret = calloc(1, len)) == NULL) {
188 strlcpy(ret, a, len);
189 for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
190 if ((m = match_list(ret, p, NULL)) != NULL) {
192 continue; /* Algorithm already present */
194 if (strlcat(ret, ",", len) >= len ||
195 strlcat(ret, p, len) >= len) {
198 return NULL; /* Shouldn't happen */
206 * Assemble a list of algorithms from a default list and a string from a
207 * configuration file. The user-provided string may begin with '+' to
208 * indicate that it should be appended to the default or '-' that the
209 * specified names should be removed.
212 kex_assemble_names(const char *def, char **list)
216 if (list == NULL || *list == NULL || **list == '\0') {
221 if ((ret = kex_names_cat(def, *list + 1)) == NULL)
222 return SSH_ERR_ALLOC_FAIL;
225 } else if (**list == '-') {
226 if ((ret = match_filter_list(def, *list + 1)) == NULL)
227 return SSH_ERR_ALLOC_FAIL;
235 /* put algorithm proposal into buffer */
237 kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
245 * add a dummy cookie, the cookie will be overwritten by
246 * kex_send_kexinit(), each time a kexinit is set
248 for (i = 0; i < KEX_COOKIE_LEN; i++) {
249 if ((r = sshbuf_put_u8(b, 0)) != 0)
252 for (i = 0; i < PROPOSAL_MAX; i++) {
253 if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
256 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
257 (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
262 /* parse buffer and return algorithm proposal */
264 kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
266 struct sshbuf *b = NULL;
269 char **proposal = NULL;
273 if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
274 return SSH_ERR_ALLOC_FAIL;
275 if ((b = sshbuf_fromb(raw)) == NULL) {
276 r = SSH_ERR_ALLOC_FAIL;
279 if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) /* skip cookie */
281 /* extract kex init proposal strings */
282 for (i = 0; i < PROPOSAL_MAX; i++) {
283 if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0)
285 debug2("%s: %s", proposal_names[i], proposal[i]);
287 /* first kex follows / reserved */
288 if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
289 (r = sshbuf_get_u32(b, &i)) != 0) /* reserved */
291 if (first_kex_follows != NULL)
292 *first_kex_follows = v;
293 debug2("first_kex_follows %d ", v);
294 debug2("reserved %u ", i);
298 if (r != 0 && proposal != NULL)
299 kex_prop_free(proposal);
305 kex_prop_free(char **proposal)
309 if (proposal == NULL)
311 for (i = 0; i < PROPOSAL_MAX; i++)
318 kex_protocol_error(int type, u_int32_t seq, struct ssh *ssh)
322 error("kex protocol error: type %d seq %u", type, seq);
323 if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
324 (r = sshpkt_put_u32(ssh, seq)) != 0 ||
325 (r = sshpkt_send(ssh)) != 0)
331 kex_reset_dispatch(struct ssh *ssh)
333 ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
334 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
338 kex_send_ext_info(struct ssh *ssh)
343 if ((algs = sshkey_alg_list(0, 1, 1, ',')) == NULL)
344 return SSH_ERR_ALLOC_FAIL;
345 if ((r = sshpkt_start(ssh, SSH2_MSG_EXT_INFO)) != 0 ||
346 (r = sshpkt_put_u32(ssh, 1)) != 0 ||
347 (r = sshpkt_put_cstring(ssh, "server-sig-algs")) != 0 ||
348 (r = sshpkt_put_cstring(ssh, algs)) != 0 ||
349 (r = sshpkt_send(ssh)) != 0)
359 kex_send_newkeys(struct ssh *ssh)
363 kex_reset_dispatch(ssh);
364 if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
365 (r = sshpkt_send(ssh)) != 0)
367 debug("SSH2_MSG_NEWKEYS sent");
368 debug("expecting SSH2_MSG_NEWKEYS");
369 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
370 if (ssh->kex->ext_info_c)
371 if ((r = kex_send_ext_info(ssh)) != 0)
377 kex_input_ext_info(int type, u_int32_t seq, struct ssh *ssh)
379 struct kex *kex = ssh->kex;
386 debug("SSH2_MSG_EXT_INFO received");
387 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
388 if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
390 for (i = 0; i < ninfo; i++) {
391 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
393 if ((r = sshpkt_get_string(ssh, &val, &vlen)) != 0) {
397 if (strcmp(name, "server-sig-algs") == 0) {
398 /* Ensure no \0 lurking in value */
399 if (memchr(val, '\0', vlen) != NULL) {
400 error("%s: nul byte in %s", __func__, name);
401 return SSH_ERR_INVALID_FORMAT;
403 debug("%s: %s=<%s>", __func__, name, val);
404 found = match_list("rsa-sha2-256", val, NULL);
409 found = match_list("rsa-sha2-512", val, NULL);
415 debug("%s: %s (unrecognised)", __func__, name);
419 return sshpkt_get_end(ssh);
423 kex_input_newkeys(int type, u_int32_t seq, struct ssh *ssh)
425 struct kex *kex = ssh->kex;
428 debug("SSH2_MSG_NEWKEYS received");
429 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
430 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
431 if ((r = sshpkt_get_end(ssh)) != 0)
433 if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0)
436 sshbuf_reset(kex->peer);
437 /* sshbuf_reset(kex->my); */
438 kex->flags &= ~KEX_INIT_SENT;
445 kex_send_kexinit(struct ssh *ssh)
448 struct kex *kex = ssh->kex;
452 return SSH_ERR_INTERNAL_ERROR;
453 if (kex->flags & KEX_INIT_SENT)
457 /* generate a random cookie */
458 if (sshbuf_len(kex->my) < KEX_COOKIE_LEN)
459 return SSH_ERR_INVALID_FORMAT;
460 if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL)
461 return SSH_ERR_INTERNAL_ERROR;
462 arc4random_buf(cookie, KEX_COOKIE_LEN);
464 if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
465 (r = sshpkt_putb(ssh, kex->my)) != 0 ||
466 (r = sshpkt_send(ssh)) != 0)
468 debug("SSH2_MSG_KEXINIT sent");
469 kex->flags |= KEX_INIT_SENT;
475 kex_input_kexinit(int type, u_int32_t seq, struct ssh *ssh)
477 struct kex *kex = ssh->kex;
483 debug("SSH2_MSG_KEXINIT received");
485 return SSH_ERR_INVALID_ARGUMENT;
487 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, NULL);
488 ptr = sshpkt_ptr(ssh, &dlen);
489 if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
493 for (i = 0; i < KEX_COOKIE_LEN; i++)
494 if ((r = sshpkt_get_u8(ssh, NULL)) != 0)
496 for (i = 0; i < PROPOSAL_MAX; i++)
497 if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0)
500 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
501 * KEX method has the server move first, but a server might be using
502 * a custom method or one that we otherwise don't support. We should
503 * be prepared to remember first_kex_follows here so we can eat a
505 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
506 * for cases where the server *doesn't* go first. I guess we should
507 * ignore it when it is set for these cases, which is what we do now.
509 if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
510 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
511 (r = sshpkt_get_end(ssh)) != 0)
514 if (!(kex->flags & KEX_INIT_SENT))
515 if ((r = kex_send_kexinit(ssh)) != 0)
517 if ((r = kex_choose_conf(ssh)) != 0)
520 if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
521 return (kex->kex[kex->kex_type])(ssh);
523 return SSH_ERR_INTERNAL_ERROR;
527 kex_new(struct ssh *ssh, char *proposal[PROPOSAL_MAX], struct kex **kexp)
533 if ((kex = calloc(1, sizeof(*kex))) == NULL)
534 return SSH_ERR_ALLOC_FAIL;
535 if ((kex->peer = sshbuf_new()) == NULL ||
536 (kex->my = sshbuf_new()) == NULL) {
537 r = SSH_ERR_ALLOC_FAIL;
540 if ((r = kex_prop2buf(kex->my, proposal)) != 0)
543 kex_reset_dispatch(ssh);
544 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
554 kex_free_newkeys(struct newkeys *newkeys)
558 if (newkeys->enc.key) {
559 explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
560 free(newkeys->enc.key);
561 newkeys->enc.key = NULL;
563 if (newkeys->enc.iv) {
564 explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
565 free(newkeys->enc.iv);
566 newkeys->enc.iv = NULL;
568 free(newkeys->enc.name);
569 explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
570 free(newkeys->comp.name);
571 explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
572 mac_clear(&newkeys->mac);
573 if (newkeys->mac.key) {
574 explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
575 free(newkeys->mac.key);
576 newkeys->mac.key = NULL;
578 free(newkeys->mac.name);
579 explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
580 explicit_bzero(newkeys, sizeof(*newkeys));
585 kex_free(struct kex *kex)
592 #ifdef OPENSSL_HAS_ECC
593 if (kex->ec_client_key)
594 EC_KEY_free(kex->ec_client_key);
595 #endif /* OPENSSL_HAS_ECC */
596 #endif /* WITH_OPENSSL */
597 for (mode = 0; mode < MODE_MAX; mode++) {
598 kex_free_newkeys(kex->newkeys[mode]);
599 kex->newkeys[mode] = NULL;
601 sshbuf_free(kex->peer);
602 sshbuf_free(kex->my);
603 free(kex->session_id);
604 free(kex->client_version_string);
605 free(kex->server_version_string);
606 free(kex->failed_choice);
607 free(kex->hostkey_alg);
613 kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
617 if ((r = kex_new(ssh, proposal, &ssh->kex)) != 0)
619 if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
628 * Request key re-exchange, returns 0 on success or a ssherr.h error
629 * code otherwise. Must not be called if KEX is incomplete or in-progress.
632 kex_start_rekex(struct ssh *ssh)
634 if (ssh->kex == NULL) {
635 error("%s: no kex", __func__);
636 return SSH_ERR_INTERNAL_ERROR;
638 if (ssh->kex->done == 0) {
639 error("%s: requested twice", __func__);
640 return SSH_ERR_INTERNAL_ERROR;
643 return kex_send_kexinit(ssh);
647 choose_enc(struct sshenc *enc, char *client, char *server)
649 char *name = match_list(client, server, NULL);
652 return SSH_ERR_NO_CIPHER_ALG_MATCH;
653 if ((enc->cipher = cipher_by_name(name)) == NULL) {
655 return SSH_ERR_INTERNAL_ERROR;
660 enc->iv_len = cipher_ivlen(enc->cipher);
662 enc->key_len = cipher_keylen(enc->cipher);
663 enc->block_size = cipher_blocksize(enc->cipher);
668 choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
670 char *name = match_list(client, server, NULL);
673 return SSH_ERR_NO_MAC_ALG_MATCH;
674 if (mac_setup(mac, name) < 0) {
676 return SSH_ERR_INTERNAL_ERROR;
678 /* truncate the key */
679 if (ssh->compat & SSH_BUG_HMAC)
688 choose_comp(struct sshcomp *comp, char *client, char *server)
690 char *name = match_list(client, server, NULL);
693 return SSH_ERR_NO_COMPRESS_ALG_MATCH;
694 if (strcmp(name, "zlib@openssh.com") == 0) {
695 comp->type = COMP_DELAYED;
696 } else if (strcmp(name, "zlib") == 0) {
697 comp->type = COMP_ZLIB;
698 } else if (strcmp(name, "none") == 0) {
699 comp->type = COMP_NONE;
702 return SSH_ERR_INTERNAL_ERROR;
709 choose_kex(struct kex *k, char *client, char *server)
711 const struct kexalg *kexalg;
713 k->name = match_list(client, server, NULL);
715 debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
717 return SSH_ERR_NO_KEX_ALG_MATCH;
718 if ((kexalg = kex_alg_by_name(k->name)) == NULL)
719 return SSH_ERR_INTERNAL_ERROR;
720 k->kex_type = kexalg->type;
721 k->hash_alg = kexalg->hash_alg;
722 k->ec_nid = kexalg->ec_nid;
727 choose_hostkeyalg(struct kex *k, char *client, char *server)
729 k->hostkey_alg = match_list(client, server, NULL);
731 debug("kex: host key algorithm: %s",
732 k->hostkey_alg ? k->hostkey_alg : "(no match)");
733 if (k->hostkey_alg == NULL)
734 return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
735 k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
736 if (k->hostkey_type == KEY_UNSPEC)
737 return SSH_ERR_INTERNAL_ERROR;
738 k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
743 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
745 static int check[] = {
746 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
751 for (idx = &check[0]; *idx != -1; idx++) {
752 if ((p = strchr(my[*idx], ',')) != NULL)
754 if ((p = strchr(peer[*idx], ',')) != NULL)
756 if (strcmp(my[*idx], peer[*idx]) != 0) {
757 debug2("proposal mismatch: my %s peer %s",
758 my[*idx], peer[*idx]);
762 debug2("proposals match");
767 kex_choose_conf(struct ssh *ssh)
769 struct kex *kex = ssh->kex;
770 struct newkeys *newkeys;
771 char **my = NULL, **peer = NULL;
772 char **cprop, **sprop;
773 int nenc, nmac, ncomp;
774 u_int mode, ctos, need, dh_need, authlen;
775 int r, first_kex_follows;
777 debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
778 if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
780 debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
781 if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
792 /* Check whether client supports ext_info_c */
796 ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
797 kex->ext_info_c = (ext != NULL);
801 /* Algorithm Negotiation */
802 if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
803 sprop[PROPOSAL_KEX_ALGS])) != 0) {
804 kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
805 peer[PROPOSAL_KEX_ALGS] = NULL;
808 if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
809 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
810 kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
811 peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
814 for (mode = 0; mode < MODE_MAX; mode++) {
815 if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
816 r = SSH_ERR_ALLOC_FAIL;
819 kex->newkeys[mode] = newkeys;
820 ctos = (!kex->server && mode == MODE_OUT) ||
821 (kex->server && mode == MODE_IN);
822 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
823 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
824 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
825 if ((r = choose_enc(&newkeys->enc, cprop[nenc],
826 sprop[nenc])) != 0) {
827 kex->failed_choice = peer[nenc];
831 authlen = cipher_authlen(newkeys->enc.cipher);
832 /* ignore mac for authenticated encryption */
834 (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
835 sprop[nmac])) != 0) {
836 kex->failed_choice = peer[nmac];
840 if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
841 sprop[ncomp])) != 0) {
842 kex->failed_choice = peer[ncomp];
846 debug("kex: %s cipher: %s MAC: %s compression: %s",
847 ctos ? "client->server" : "server->client",
849 authlen == 0 ? newkeys->mac.name : "<implicit>",
853 for (mode = 0; mode < MODE_MAX; mode++) {
854 newkeys = kex->newkeys[mode];
855 need = MAXIMUM(need, newkeys->enc.key_len);
856 need = MAXIMUM(need, newkeys->enc.block_size);
857 need = MAXIMUM(need, newkeys->enc.iv_len);
858 need = MAXIMUM(need, newkeys->mac.key_len);
859 dh_need = MAXIMUM(dh_need, cipher_seclen(newkeys->enc.cipher));
860 dh_need = MAXIMUM(dh_need, newkeys->enc.block_size);
861 dh_need = MAXIMUM(dh_need, newkeys->enc.iv_len);
862 dh_need = MAXIMUM(dh_need, newkeys->mac.key_len);
864 /* XXX need runden? */
866 kex->dh_need = dh_need;
868 /* ignore the next message if the proposals do not match */
869 if (first_kex_follows && !proposals_match(my, peer) &&
870 !(ssh->compat & SSH_BUG_FIRSTKEX))
871 ssh->dispatch_skip_packets = 1;
880 derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
881 const struct sshbuf *shared_secret, u_char **keyp)
883 struct kex *kex = ssh->kex;
884 struct ssh_digest_ctx *hashctx = NULL;
891 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
892 return SSH_ERR_INVALID_ARGUMENT;
893 if ((digest = calloc(1, ROUNDUP(need, mdsz))) == NULL) {
894 r = SSH_ERR_ALLOC_FAIL;
898 /* K1 = HASH(K || H || "A" || session_id) */
899 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
900 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
901 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
902 ssh_digest_update(hashctx, &c, 1) != 0 ||
903 ssh_digest_update(hashctx, kex->session_id,
904 kex->session_id_len) != 0 ||
905 ssh_digest_final(hashctx, digest, mdsz) != 0) {
906 r = SSH_ERR_LIBCRYPTO_ERROR;
909 ssh_digest_free(hashctx);
914 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
915 * Key = K1 || K2 || ... || Kn
917 for (have = mdsz; need > have; have += mdsz) {
918 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
919 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
920 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
921 ssh_digest_update(hashctx, digest, have) != 0 ||
922 ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
923 r = SSH_ERR_LIBCRYPTO_ERROR;
926 ssh_digest_free(hashctx);
930 fprintf(stderr, "key '%c'== ", c);
931 dump_digest("key", digest, need);
938 ssh_digest_free(hashctx);
944 kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
945 const struct sshbuf *shared_secret)
947 struct kex *kex = ssh->kex;
949 u_int i, j, mode, ctos;
952 for (i = 0; i < NKEYS; i++) {
953 if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
954 shared_secret, &keys[i])) != 0) {
955 for (j = 0; j < i; j++)
960 for (mode = 0; mode < MODE_MAX; mode++) {
961 ctos = (!kex->server && mode == MODE_OUT) ||
962 (kex->server && mode == MODE_IN);
963 kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
964 kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
965 kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
972 kex_derive_keys_bn(struct ssh *ssh, u_char *hash, u_int hashlen,
973 const BIGNUM *secret)
975 struct sshbuf *shared_secret;
978 if ((shared_secret = sshbuf_new()) == NULL)
979 return SSH_ERR_ALLOC_FAIL;
980 if ((r = sshbuf_put_bignum2(shared_secret, secret)) == 0)
981 r = kex_derive_keys(ssh, hash, hashlen, shared_secret);
982 sshbuf_free(shared_secret);
988 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
990 dump_digest(char *msg, u_char *digest, int len)
992 fprintf(stderr, "%s\n", msg);
993 sshbuf_dump_data(digest, len, stderr);