1 /* $OpenBSD: kex.c,v 1.118 2016/05/02 10:26:04 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.
28 #include <sys/param.h> /* MAX roundup */
37 #include <openssl/crypto.h>
38 #include <openssl/dh.h>
58 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
59 # if defined(HAVE_EVP_SHA256)
60 # define evp_ssh_sha256 EVP_sha256
62 extern const EVP_MD *evp_ssh_sha256(void);
67 static int kex_choose_conf(struct ssh *);
68 static int kex_input_newkeys(int, u_int32_t, void *);
70 static const char *proposal_names[PROPOSAL_MAX] = {
72 "host key algorithms",
89 static const struct kexalg kexalgs[] = {
91 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
92 { KEX_DH14_SHA1, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
93 { KEX_DH14_SHA256, KEX_DH_GRP14_SHA256, 0, SSH_DIGEST_SHA256 },
94 { KEX_DH16_SHA512, KEX_DH_GRP16_SHA512, 0, SSH_DIGEST_SHA512 },
95 { KEX_DH18_SHA512, KEX_DH_GRP18_SHA512, 0, SSH_DIGEST_SHA512 },
96 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
97 #ifdef HAVE_EVP_SHA256
98 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
99 #endif /* HAVE_EVP_SHA256 */
100 #ifdef OPENSSL_HAS_ECC
101 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
102 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
103 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
105 # ifdef OPENSSL_HAS_NISTP521
106 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
108 # endif /* OPENSSL_HAS_NISTP521 */
109 #endif /* OPENSSL_HAS_ECC */
110 #endif /* WITH_OPENSSL */
111 #if defined(HAVE_EVP_SHA256) || !defined(WITH_OPENSSL)
112 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
113 #endif /* HAVE_EVP_SHA256 || !WITH_OPENSSL */
118 kex_alg_list(char sep)
120 char *ret = NULL, *tmp;
121 size_t nlen, rlen = 0;
122 const struct kexalg *k;
124 for (k = kexalgs; k->name != NULL; k++) {
127 nlen = strlen(k->name);
128 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
133 memcpy(ret + rlen, k->name, nlen + 1);
139 static const struct kexalg *
140 kex_alg_by_name(const char *name)
142 const struct kexalg *k;
144 for (k = kexalgs; k->name != NULL; k++) {
145 if (strcmp(k->name, name) == 0)
151 /* Validate KEX method name list */
153 kex_names_valid(const char *names)
157 if (names == NULL || strcmp(names, "") == 0)
159 if ((s = cp = strdup(names)) == NULL)
161 for ((p = strsep(&cp, ",")); p && *p != '\0';
162 (p = strsep(&cp, ","))) {
163 if (kex_alg_by_name(p) == NULL) {
164 error("Unsupported KEX algorithm \"%.100s\"", p);
169 debug3("kex names ok: [%s]", names);
175 * Concatenate algorithm names, avoiding duplicates in the process.
176 * Caller must free returned string.
179 kex_names_cat(const char *a, const char *b)
181 char *ret = NULL, *tmp = NULL, *cp, *p;
184 if (a == NULL || *a == '\0')
186 if (b == NULL || *b == '\0')
188 if (strlen(b) > 1024*1024)
190 len = strlen(a) + strlen(b) + 2;
191 if ((tmp = cp = strdup(b)) == NULL ||
192 (ret = calloc(1, len)) == NULL) {
196 strlcpy(ret, a, len);
197 for ((p = strsep(&cp, ",")); p && *p != '\0'; (p = strsep(&cp, ","))) {
198 if (match_list(ret, p, NULL) != NULL)
199 continue; /* Algorithm already present */
200 if (strlcat(ret, ",", len) >= len ||
201 strlcat(ret, p, len) >= len) {
204 return NULL; /* Shouldn't happen */
212 * Assemble a list of algorithms from a default list and a string from a
213 * configuration file. The user-provided string may begin with '+' to
214 * indicate that it should be appended to the default.
217 kex_assemble_names(const char *def, char **list)
221 if (list == NULL || *list == NULL || **list == '\0') {
229 if ((ret = kex_names_cat(def, *list + 1)) == NULL)
230 return SSH_ERR_ALLOC_FAIL;
236 /* put algorithm proposal into buffer */
238 kex_prop2buf(struct sshbuf *b, char *proposal[PROPOSAL_MAX])
246 * add a dummy cookie, the cookie will be overwritten by
247 * kex_send_kexinit(), each time a kexinit is set
249 for (i = 0; i < KEX_COOKIE_LEN; i++) {
250 if ((r = sshbuf_put_u8(b, 0)) != 0)
253 for (i = 0; i < PROPOSAL_MAX; i++) {
254 if ((r = sshbuf_put_cstring(b, proposal[i])) != 0)
257 if ((r = sshbuf_put_u8(b, 0)) != 0 || /* first_kex_packet_follows */
258 (r = sshbuf_put_u32(b, 0)) != 0) /* uint32 reserved */
263 /* parse buffer and return algorithm proposal */
265 kex_buf2prop(struct sshbuf *raw, int *first_kex_follows, char ***propp)
267 struct sshbuf *b = NULL;
270 char **proposal = NULL;
274 if ((proposal = calloc(PROPOSAL_MAX, sizeof(char *))) == NULL)
275 return SSH_ERR_ALLOC_FAIL;
276 if ((b = sshbuf_fromb(raw)) == NULL) {
277 r = SSH_ERR_ALLOC_FAIL;
280 if ((r = sshbuf_consume(b, KEX_COOKIE_LEN)) != 0) /* skip cookie */
282 /* extract kex init proposal strings */
283 for (i = 0; i < PROPOSAL_MAX; i++) {
284 if ((r = sshbuf_get_cstring(b, &(proposal[i]), NULL)) != 0)
286 debug2("%s: %s", proposal_names[i], proposal[i]);
288 /* first kex follows / reserved */
289 if ((r = sshbuf_get_u8(b, &v)) != 0 || /* first_kex_follows */
290 (r = sshbuf_get_u32(b, &i)) != 0) /* reserved */
292 if (first_kex_follows != NULL)
293 *first_kex_follows = v;
294 debug2("first_kex_follows %d ", v);
295 debug2("reserved %u ", i);
299 if (r != 0 && proposal != NULL)
300 kex_prop_free(proposal);
306 kex_prop_free(char **proposal)
310 if (proposal == NULL)
312 for (i = 0; i < PROPOSAL_MAX; i++)
319 kex_protocol_error(int type, u_int32_t seq, void *ctxt)
321 struct ssh *ssh = active_state; /* XXX */
324 error("kex protocol error: type %d seq %u", type, seq);
325 if ((r = sshpkt_start(ssh, SSH2_MSG_UNIMPLEMENTED)) != 0 ||
326 (r = sshpkt_put_u32(ssh, seq)) != 0 ||
327 (r = sshpkt_send(ssh)) != 0)
333 kex_reset_dispatch(struct ssh *ssh)
335 ssh_dispatch_range(ssh, SSH2_MSG_TRANSPORT_MIN,
336 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
337 ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
341 kex_send_ext_info(struct ssh *ssh)
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, "rsa-sha2-256,rsa-sha2-512")) != 0 ||
349 (r = sshpkt_send(ssh)) != 0)
355 kex_send_newkeys(struct ssh *ssh)
359 kex_reset_dispatch(ssh);
360 if ((r = sshpkt_start(ssh, SSH2_MSG_NEWKEYS)) != 0 ||
361 (r = sshpkt_send(ssh)) != 0)
363 debug("SSH2_MSG_NEWKEYS sent");
364 debug("expecting SSH2_MSG_NEWKEYS");
365 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_input_newkeys);
366 if (ssh->kex->ext_info_c)
367 if ((r = kex_send_ext_info(ssh)) != 0)
373 kex_input_ext_info(int type, u_int32_t seq, void *ctxt)
375 struct ssh *ssh = ctxt;
376 struct kex *kex = ssh->kex;
378 char *name, *val, *found;
381 debug("SSH2_MSG_EXT_INFO received");
382 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_protocol_error);
383 if ((r = sshpkt_get_u32(ssh, &ninfo)) != 0)
385 for (i = 0; i < ninfo; i++) {
386 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0)
388 if ((r = sshpkt_get_cstring(ssh, &val, NULL)) != 0) {
392 debug("%s: %s=<%s>", __func__, name, val);
393 if (strcmp(name, "server-sig-algs") == 0) {
394 found = match_list("rsa-sha2-256", val, NULL);
399 found = match_list("rsa-sha2-512", val, NULL);
408 return sshpkt_get_end(ssh);
412 kex_input_newkeys(int type, u_int32_t seq, void *ctxt)
414 struct ssh *ssh = ctxt;
415 struct kex *kex = ssh->kex;
418 debug("SSH2_MSG_NEWKEYS received");
419 ssh_dispatch_set(ssh, SSH2_MSG_NEWKEYS, &kex_protocol_error);
420 if ((r = sshpkt_get_end(ssh)) != 0)
423 sshbuf_reset(kex->peer);
424 /* sshbuf_reset(kex->my); */
425 kex->flags &= ~KEX_INIT_SENT;
432 kex_send_kexinit(struct ssh *ssh)
435 struct kex *kex = ssh->kex;
439 return SSH_ERR_INTERNAL_ERROR;
440 if (kex->flags & KEX_INIT_SENT)
444 /* generate a random cookie */
445 if (sshbuf_len(kex->my) < KEX_COOKIE_LEN)
446 return SSH_ERR_INVALID_FORMAT;
447 if ((cookie = sshbuf_mutable_ptr(kex->my)) == NULL)
448 return SSH_ERR_INTERNAL_ERROR;
449 arc4random_buf(cookie, KEX_COOKIE_LEN);
451 if ((r = sshpkt_start(ssh, SSH2_MSG_KEXINIT)) != 0 ||
452 (r = sshpkt_putb(ssh, kex->my)) != 0 ||
453 (r = sshpkt_send(ssh)) != 0)
455 debug("SSH2_MSG_KEXINIT sent");
456 kex->flags |= KEX_INIT_SENT;
462 kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
464 struct ssh *ssh = ctxt;
465 struct kex *kex = ssh->kex;
471 debug("SSH2_MSG_KEXINIT received");
473 return SSH_ERR_INVALID_ARGUMENT;
475 ptr = sshpkt_ptr(ssh, &dlen);
476 if ((r = sshbuf_put(kex->peer, ptr, dlen)) != 0)
480 for (i = 0; i < KEX_COOKIE_LEN; i++)
481 if ((r = sshpkt_get_u8(ssh, NULL)) != 0)
483 for (i = 0; i < PROPOSAL_MAX; i++)
484 if ((r = sshpkt_get_string(ssh, NULL, NULL)) != 0)
487 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
488 * KEX method has the server move first, but a server might be using
489 * a custom method or one that we otherwise don't support. We should
490 * be prepared to remember first_kex_follows here so we can eat a
492 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
493 * for cases where the server *doesn't* go first. I guess we should
494 * ignore it when it is set for these cases, which is what we do now.
496 if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || /* first_kex_follows */
497 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* reserved */
498 (r = sshpkt_get_end(ssh)) != 0)
501 if (!(kex->flags & KEX_INIT_SENT))
502 if ((r = kex_send_kexinit(ssh)) != 0)
504 if ((r = kex_choose_conf(ssh)) != 0)
507 if (kex->kex_type < KEX_MAX && kex->kex[kex->kex_type] != NULL)
508 return (kex->kex[kex->kex_type])(ssh);
510 return SSH_ERR_INTERNAL_ERROR;
514 kex_new(struct ssh *ssh, char *proposal[PROPOSAL_MAX], struct kex **kexp)
520 if ((kex = calloc(1, sizeof(*kex))) == NULL)
521 return SSH_ERR_ALLOC_FAIL;
522 if ((kex->peer = sshbuf_new()) == NULL ||
523 (kex->my = sshbuf_new()) == NULL) {
524 r = SSH_ERR_ALLOC_FAIL;
527 if ((r = kex_prop2buf(kex->my, proposal)) != 0)
530 kex_reset_dispatch(ssh);
540 kex_free_newkeys(struct newkeys *newkeys)
544 if (newkeys->enc.key) {
545 explicit_bzero(newkeys->enc.key, newkeys->enc.key_len);
546 free(newkeys->enc.key);
547 newkeys->enc.key = NULL;
549 if (newkeys->enc.iv) {
550 explicit_bzero(newkeys->enc.iv, newkeys->enc.iv_len);
551 free(newkeys->enc.iv);
552 newkeys->enc.iv = NULL;
554 free(newkeys->enc.name);
555 explicit_bzero(&newkeys->enc, sizeof(newkeys->enc));
556 free(newkeys->comp.name);
557 explicit_bzero(&newkeys->comp, sizeof(newkeys->comp));
558 mac_clear(&newkeys->mac);
559 if (newkeys->mac.key) {
560 explicit_bzero(newkeys->mac.key, newkeys->mac.key_len);
561 free(newkeys->mac.key);
562 newkeys->mac.key = NULL;
564 free(newkeys->mac.name);
565 explicit_bzero(&newkeys->mac, sizeof(newkeys->mac));
566 explicit_bzero(newkeys, sizeof(*newkeys));
571 kex_free(struct kex *kex)
578 #ifdef OPENSSL_HAS_ECC
579 if (kex->ec_client_key)
580 EC_KEY_free(kex->ec_client_key);
581 #endif /* OPENSSL_HAS_ECC */
582 #endif /* WITH_OPENSSL */
583 for (mode = 0; mode < MODE_MAX; mode++) {
584 kex_free_newkeys(kex->newkeys[mode]);
585 kex->newkeys[mode] = NULL;
587 sshbuf_free(kex->peer);
588 sshbuf_free(kex->my);
589 free(kex->session_id);
590 free(kex->client_version_string);
591 free(kex->server_version_string);
592 free(kex->failed_choice);
593 free(kex->hostkey_alg);
599 kex_setup(struct ssh *ssh, char *proposal[PROPOSAL_MAX])
603 if ((r = kex_new(ssh, proposal, &ssh->kex)) != 0)
605 if ((r = kex_send_kexinit(ssh)) != 0) { /* we start */
614 * Request key re-exchange, returns 0 on success or a ssherr.h error
615 * code otherwise. Must not be called if KEX is incomplete or in-progress.
618 kex_start_rekex(struct ssh *ssh)
620 if (ssh->kex == NULL) {
621 error("%s: no kex", __func__);
622 return SSH_ERR_INTERNAL_ERROR;
624 if (ssh->kex->done == 0) {
625 error("%s: requested twice", __func__);
626 return SSH_ERR_INTERNAL_ERROR;
629 return kex_send_kexinit(ssh);
633 choose_enc(struct sshenc *enc, char *client, char *server)
635 char *name = match_list(client, server, NULL);
638 return SSH_ERR_NO_CIPHER_ALG_MATCH;
639 if ((enc->cipher = cipher_by_name(name)) == NULL)
640 return SSH_ERR_INTERNAL_ERROR;
644 enc->iv_len = cipher_ivlen(enc->cipher);
646 enc->key_len = cipher_keylen(enc->cipher);
647 enc->block_size = cipher_blocksize(enc->cipher);
652 choose_mac(struct ssh *ssh, struct sshmac *mac, char *client, char *server)
654 char *name = match_list(client, server, NULL);
657 return SSH_ERR_NO_MAC_ALG_MATCH;
658 if (mac_setup(mac, name) < 0)
659 return SSH_ERR_INTERNAL_ERROR;
660 /* truncate the key */
661 if (ssh->compat & SSH_BUG_HMAC)
670 choose_comp(struct sshcomp *comp, char *client, char *server)
672 char *name = match_list(client, server, NULL);
675 return SSH_ERR_NO_COMPRESS_ALG_MATCH;
676 if (strcmp(name, "zlib@openssh.com") == 0) {
677 comp->type = COMP_DELAYED;
678 } else if (strcmp(name, "zlib") == 0) {
679 comp->type = COMP_ZLIB;
680 } else if (strcmp(name, "none") == 0) {
681 comp->type = COMP_NONE;
683 return SSH_ERR_INTERNAL_ERROR;
690 choose_kex(struct kex *k, char *client, char *server)
692 const struct kexalg *kexalg;
694 k->name = match_list(client, server, NULL);
696 debug("kex: algorithm: %s", k->name ? k->name : "(no match)");
698 return SSH_ERR_NO_KEX_ALG_MATCH;
699 if ((kexalg = kex_alg_by_name(k->name)) == NULL)
700 return SSH_ERR_INTERNAL_ERROR;
701 k->kex_type = kexalg->type;
702 k->hash_alg = kexalg->hash_alg;
703 k->ec_nid = kexalg->ec_nid;
708 choose_hostkeyalg(struct kex *k, char *client, char *server)
710 k->hostkey_alg = match_list(client, server, NULL);
712 debug("kex: host key algorithm: %s",
713 k->hostkey_alg ? k->hostkey_alg : "(no match)");
714 if (k->hostkey_alg == NULL)
715 return SSH_ERR_NO_HOSTKEY_ALG_MATCH;
716 k->hostkey_type = sshkey_type_from_name(k->hostkey_alg);
717 if (k->hostkey_type == KEY_UNSPEC)
718 return SSH_ERR_INTERNAL_ERROR;
719 k->hostkey_nid = sshkey_ecdsa_nid_from_name(k->hostkey_alg);
724 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
726 static int check[] = {
727 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
732 for (idx = &check[0]; *idx != -1; idx++) {
733 if ((p = strchr(my[*idx], ',')) != NULL)
735 if ((p = strchr(peer[*idx], ',')) != NULL)
737 if (strcmp(my[*idx], peer[*idx]) != 0) {
738 debug2("proposal mismatch: my %s peer %s",
739 my[*idx], peer[*idx]);
743 debug2("proposals match");
748 kex_choose_conf(struct ssh *ssh)
750 struct kex *kex = ssh->kex;
751 struct newkeys *newkeys;
752 char **my = NULL, **peer = NULL;
753 char **cprop, **sprop;
754 int nenc, nmac, ncomp;
755 u_int mode, ctos, need, dh_need, authlen;
756 int r, first_kex_follows;
758 debug2("local %s KEXINIT proposal", kex->server ? "server" : "client");
759 if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
761 debug2("peer %s KEXINIT proposal", kex->server ? "client" : "server");
762 if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
773 /* Check whether client supports ext_info_c */
777 ext = match_list("ext-info-c", peer[PROPOSAL_KEX_ALGS], NULL);
784 /* Algorithm Negotiation */
785 if ((r = choose_kex(kex, cprop[PROPOSAL_KEX_ALGS],
786 sprop[PROPOSAL_KEX_ALGS])) != 0) {
787 kex->failed_choice = peer[PROPOSAL_KEX_ALGS];
788 peer[PROPOSAL_KEX_ALGS] = NULL;
791 if ((r = choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
792 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS])) != 0) {
793 kex->failed_choice = peer[PROPOSAL_SERVER_HOST_KEY_ALGS];
794 peer[PROPOSAL_SERVER_HOST_KEY_ALGS] = NULL;
797 for (mode = 0; mode < MODE_MAX; mode++) {
798 if ((newkeys = calloc(1, sizeof(*newkeys))) == NULL) {
799 r = SSH_ERR_ALLOC_FAIL;
802 kex->newkeys[mode] = newkeys;
803 ctos = (!kex->server && mode == MODE_OUT) ||
804 (kex->server && mode == MODE_IN);
805 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
806 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
807 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
808 if ((r = choose_enc(&newkeys->enc, cprop[nenc],
809 sprop[nenc])) != 0) {
810 kex->failed_choice = peer[nenc];
814 authlen = cipher_authlen(newkeys->enc.cipher);
815 /* ignore mac for authenticated encryption */
817 (r = choose_mac(ssh, &newkeys->mac, cprop[nmac],
818 sprop[nmac])) != 0) {
819 kex->failed_choice = peer[nmac];
823 if ((r = choose_comp(&newkeys->comp, cprop[ncomp],
824 sprop[ncomp])) != 0) {
825 kex->failed_choice = peer[ncomp];
829 debug("kex: %s cipher: %s MAC: %s compression: %s",
830 ctos ? "client->server" : "server->client",
832 authlen == 0 ? newkeys->mac.name : "<implicit>",
836 for (mode = 0; mode < MODE_MAX; mode++) {
837 newkeys = kex->newkeys[mode];
838 need = MAX(need, newkeys->enc.key_len);
839 need = MAX(need, newkeys->enc.block_size);
840 need = MAX(need, newkeys->enc.iv_len);
841 need = MAX(need, newkeys->mac.key_len);
842 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher));
843 dh_need = MAX(dh_need, newkeys->enc.block_size);
844 dh_need = MAX(dh_need, newkeys->enc.iv_len);
845 dh_need = MAX(dh_need, newkeys->mac.key_len);
847 /* XXX need runden? */
849 kex->dh_need = dh_need;
851 /* ignore the next message if the proposals do not match */
852 if (first_kex_follows && !proposals_match(my, peer) &&
853 !(ssh->compat & SSH_BUG_FIRSTKEX))
854 ssh->dispatch_skip_packets = 1;
863 derive_key(struct ssh *ssh, int id, u_int need, u_char *hash, u_int hashlen,
864 const struct sshbuf *shared_secret, u_char **keyp)
866 struct kex *kex = ssh->kex;
867 struct ssh_digest_ctx *hashctx = NULL;
874 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
875 return SSH_ERR_INVALID_ARGUMENT;
876 if ((digest = calloc(1, roundup(need, mdsz))) == NULL) {
877 r = SSH_ERR_ALLOC_FAIL;
881 /* K1 = HASH(K || H || "A" || session_id) */
882 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
883 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
884 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
885 ssh_digest_update(hashctx, &c, 1) != 0 ||
886 ssh_digest_update(hashctx, kex->session_id,
887 kex->session_id_len) != 0 ||
888 ssh_digest_final(hashctx, digest, mdsz) != 0) {
889 r = SSH_ERR_LIBCRYPTO_ERROR;
892 ssh_digest_free(hashctx);
897 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
898 * Key = K1 || K2 || ... || Kn
900 for (have = mdsz; need > have; have += mdsz) {
901 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL ||
902 ssh_digest_update_buffer(hashctx, shared_secret) != 0 ||
903 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
904 ssh_digest_update(hashctx, digest, have) != 0 ||
905 ssh_digest_final(hashctx, digest + have, mdsz) != 0) {
906 r = SSH_ERR_LIBCRYPTO_ERROR;
909 ssh_digest_free(hashctx);
913 fprintf(stderr, "key '%c'== ", c);
914 dump_digest("key", digest, need);
921 ssh_digest_free(hashctx);
927 kex_derive_keys(struct ssh *ssh, u_char *hash, u_int hashlen,
928 const struct sshbuf *shared_secret)
930 struct kex *kex = ssh->kex;
932 u_int i, j, mode, ctos;
935 for (i = 0; i < NKEYS; i++) {
936 if ((r = derive_key(ssh, 'A'+i, kex->we_need, hash, hashlen,
937 shared_secret, &keys[i])) != 0) {
938 for (j = 0; j < i; j++)
943 for (mode = 0; mode < MODE_MAX; mode++) {
944 ctos = (!kex->server && mode == MODE_OUT) ||
945 (kex->server && mode == MODE_IN);
946 kex->newkeys[mode]->enc.iv = keys[ctos ? 0 : 1];
947 kex->newkeys[mode]->enc.key = keys[ctos ? 2 : 3];
948 kex->newkeys[mode]->mac.key = keys[ctos ? 4 : 5];
955 kex_derive_keys_bn(struct ssh *ssh, u_char *hash, u_int hashlen,
956 const BIGNUM *secret)
958 struct sshbuf *shared_secret;
961 if ((shared_secret = sshbuf_new()) == NULL)
962 return SSH_ERR_ALLOC_FAIL;
963 if ((r = sshbuf_put_bignum2(shared_secret, secret)) == 0)
964 r = kex_derive_keys(ssh, hash, hashlen, shared_secret);
965 sshbuf_free(shared_secret);
972 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
973 u_int8_t cookie[8], u_int8_t id[16])
975 u_int8_t hbuf[2048], sbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH];
976 struct ssh_digest_ctx *hashctx = NULL;
980 hlen = BN_num_bytes(host_modulus);
981 slen = BN_num_bytes(server_modulus);
982 if (hlen < (512 / 8) || (u_int)hlen > sizeof(hbuf) ||
983 slen < (512 / 8) || (u_int)slen > sizeof(sbuf))
984 return SSH_ERR_KEY_BITS_MISMATCH;
985 if (BN_bn2bin(host_modulus, hbuf) <= 0 ||
986 BN_bn2bin(server_modulus, sbuf) <= 0) {
987 r = SSH_ERR_LIBCRYPTO_ERROR;
990 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) {
991 r = SSH_ERR_ALLOC_FAIL;
994 if (ssh_digest_update(hashctx, hbuf, hlen) != 0 ||
995 ssh_digest_update(hashctx, sbuf, slen) != 0 ||
996 ssh_digest_update(hashctx, cookie, 8) != 0 ||
997 ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) {
998 r = SSH_ERR_LIBCRYPTO_ERROR;
1001 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5));
1004 ssh_digest_free(hashctx);
1005 explicit_bzero(hbuf, sizeof(hbuf));
1006 explicit_bzero(sbuf, sizeof(sbuf));
1007 explicit_bzero(obuf, sizeof(obuf));
1012 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1014 dump_digest(char *msg, u_char *digest, int len)
1016 fprintf(stderr, "%s\n", msg);
1017 sshbuf_dump_data(digest, len, stderr);