[openssh.git] / kexdh.c

/*
 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"
RCSID("$OpenBSD: kexdh.c,v 1.17 2002/02/28 15:46:33 markus Exp $");

#include <openssl/crypto.h>
#include <openssl/bn.h>

#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "key.h"
#include "kex.h"
#include "log.h"
#include "packet.h"
#include "dh.h"
#include "ssh2.h"
#include "monitor.h"
#include "monitor_wrap.h"

/* Imports */
extern int use_privsep;
extern int mm_recvfd;

static u_char *
kex_dh_hash(
    char *client_version_string,
    char *server_version_string,
    char *ckexinit, int ckexinitlen,
    char *skexinit, int skexinitlen,
    u_char *serverhostkeyblob, int sbloblen,
    BIGNUM *client_dh_pub,
    BIGNUM *server_dh_pub,
    BIGNUM *shared_secret)
{
	Buffer b;
	static u_char digest[EVP_MAX_MD_SIZE];
	const EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;

	buffer_init(&b);
	buffer_put_cstring(&b, client_version_string);
	buffer_put_cstring(&b, server_version_string);

	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
	buffer_put_int(&b, ckexinitlen+1);
	buffer_put_char(&b, SSH2_MSG_KEXINIT);
	buffer_append(&b, ckexinit, ckexinitlen);
	buffer_put_int(&b, skexinitlen+1);
	buffer_put_char(&b, SSH2_MSG_KEXINIT);
	buffer_append(&b, skexinit, skexinitlen);

	buffer_put_string(&b, serverhostkeyblob, sbloblen);
	buffer_put_bignum2(&b, client_dh_pub);
	buffer_put_bignum2(&b, server_dh_pub);
	buffer_put_bignum2(&b, shared_secret);

#ifdef DEBUG_KEX
	buffer_dump(&b);
#endif
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	EVP_DigestFinal(&md, digest, NULL);

	buffer_free(&b);

#ifdef DEBUG_KEX
	dump_digest("hash", digest, EVP_MD_size(evp_md));
#endif
	return digest;
}

/* client */

static void
kexdh_client(Kex *kex)
{
	BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
	DH *dh;
	Key *server_host_key;
	u_char *server_host_key_blob = NULL, *signature = NULL;
	u_char *kbuf, *hash;
	u_int klen, kout, slen, sbloblen;

	/* generate and send 'e', client DH public key */
	dh = dh_new_group1();
	dh_gen_key(dh, kex->we_need * 8);
	packet_start(SSH2_MSG_KEXDH_INIT);
	packet_put_bignum2(dh->pub_key);
	packet_send();

	debug("sending SSH2_MSG_KEXDH_INIT");
#ifdef DEBUG_KEXDH
	DHparams_print_fp(stderr, dh);
	fprintf(stderr, "pub= ");
	BN_print_fp(stderr, dh->pub_key);
	fprintf(stderr, "\n");
#endif

	debug("expecting SSH2_MSG_KEXDH_REPLY");
	packet_read_expect(SSH2_MSG_KEXDH_REPLY);

	/* key, cert */
	server_host_key_blob = packet_get_string(&sbloblen);
	server_host_key = key_from_blob(server_host_key_blob, sbloblen);
	if (server_host_key == NULL)
		fatal("cannot decode server_host_key_blob");
	if (server_host_key->type != kex->hostkey_type)
		fatal("type mismatch for decoded server_host_key_blob");
	if (kex->verify_host_key == NULL)
		fatal("cannot verify server_host_key");
	if (kex->verify_host_key(server_host_key) == -1)
		fatal("server_host_key verification failed");

	/* DH paramter f, server public DH key */
	if ((dh_server_pub = BN_new()) == NULL)
		fatal("dh_server_pub == NULL");
	packet_get_bignum2(dh_server_pub);

#ifdef DEBUG_KEXDH
	fprintf(stderr, "dh_server_pub= ");
	BN_print_fp(stderr, dh_server_pub);
	fprintf(stderr, "\n");
	debug("bits %d", BN_num_bits(dh_server_pub));
#endif

	/* signed H */
	signature = packet_get_string(&slen);
	packet_check_eom();

	if (!dh_pub_is_valid(dh, dh_server_pub))
		packet_disconnect("bad server public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	kout = DH_compute_key(kbuf, dh_server_pub, dh);
#ifdef DEBUG_KEXDH
	dump_digest("shared secret", kbuf, kout);
#endif
	if ((shared_secret = BN_new()) == NULL)
		fatal("kexdh_client: BN_new failed");
	BN_bin2bn(kbuf, kout, shared_secret);
	memset(kbuf, 0, klen);
	xfree(kbuf);

	/* calc and verify H */
	hash = kex_dh_hash(
	    kex->client_version_string,
	    kex->server_version_string,
	    buffer_ptr(&kex->my), buffer_len(&kex->my),
	    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	    server_host_key_blob, sbloblen,
	    dh->pub_key,
	    dh_server_pub,
	    shared_secret
	);
	xfree(server_host_key_blob);
	BN_clear_free(dh_server_pub);
	DH_free(dh);

	if (key_verify(server_host_key, signature, slen, hash, 20) != 1)
		fatal("key_verify failed for server_host_key");
	key_free(server_host_key);
	xfree(signature);

	/* save session id */
	if (kex->session_id == NULL) {
		kex->session_id_len = 20;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}

	kex_derive_keys(kex, hash, shared_secret);
	BN_clear_free(shared_secret);
	kex_finish(kex);
}

/* server */

static void
kexdh_server(Kex *kex)
{
	BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
	DH *dh;
	Key *server_host_key;
	u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
	u_int sbloblen, klen, kout;
	u_int slen;

	/* generate server DH public key */
	dh = dh_new_group1();
	dh_gen_key(dh, kex->we_need * 8);

	debug("expecting SSH2_MSG_KEXDH_INIT");
	packet_read_expect(SSH2_MSG_KEXDH_INIT);

	if (kex->load_host_key == NULL)
		fatal("Cannot load hostkey");
	server_host_key = kex->load_host_key(kex->hostkey_type);
	if (server_host_key == NULL)
		fatal("Unsupported hostkey type %d", kex->hostkey_type);

	/* key, cert */
	if ((dh_client_pub = BN_new()) == NULL)
		fatal("dh_client_pub == NULL");
	packet_get_bignum2(dh_client_pub);
	packet_check_eom();

#ifdef DEBUG_KEXDH
	fprintf(stderr, "dh_client_pub= ");
	BN_print_fp(stderr, dh_client_pub);
	fprintf(stderr, "\n");
	debug("bits %d", BN_num_bits(dh_client_pub));
#endif

#ifdef DEBUG_KEXDH
	DHparams_print_fp(stderr, dh);
	fprintf(stderr, "pub= ");
	BN_print_fp(stderr, dh->pub_key);
	fprintf(stderr, "\n");
#endif
	if (!dh_pub_is_valid(dh, dh_client_pub))
		packet_disconnect("bad client public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	kout = DH_compute_key(kbuf, dh_client_pub, dh);
#ifdef DEBUG_KEXDH
	dump_digest("shared secret", kbuf, kout);
#endif
	if ((shared_secret = BN_new()) == NULL)
		fatal("kexdh_server: BN_new failed");
	BN_bin2bn(kbuf, kout, shared_secret);
	memset(kbuf, 0, klen);
	xfree(kbuf);

	key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);

	/* calc H */
	hash = kex_dh_hash(
	    kex->client_version_string,
	    kex->server_version_string,
	    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	    buffer_ptr(&kex->my), buffer_len(&kex->my),
	    server_host_key_blob, sbloblen,
	    dh_client_pub,
	    dh->pub_key,
	    shared_secret
	);
	BN_clear_free(dh_client_pub);

	/* save session id := H */
	/* XXX hashlen depends on KEX */
	if (kex->session_id == NULL) {
		kex->session_id_len = 20;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}

	/* sign H */
	/* XXX hashlen depends on KEX */
	if (use_privsep)
		mm_key_sign(mm_recvfd,
		    kex->host_key_index(server_host_key),
		    &signature, &slen, hash, 20);
	else
		key_sign(server_host_key, &signature, &slen, hash, 20);

	/* destroy_sensitive_data(); */

	/* send server hostkey, DH pubkey 'f' and singed H */
	packet_start(SSH2_MSG_KEXDH_REPLY);
	packet_put_string(server_host_key_blob, sbloblen);
	packet_put_bignum2(dh->pub_key);	/* f */
	packet_put_string(signature, slen);
	packet_send();

	xfree(signature);
	xfree(server_host_key_blob);
	/* have keys, free DH */
	DH_free(dh);

	kex_derive_keys(kex, hash, shared_secret);
	BN_clear_free(shared_secret);
	kex_finish(kex);
}

void
kexdh(Kex *kex)
{
	if (kex->server)
		kexdh_server(kex);
	else
		kexdh_client(kex);
}
Commit	Line	Data
0bc35151	1	/*
	2	* Copyright (c) 2001 Markus Friedl. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
714954dc	26	RCSID("$OpenBSD: kexdh.c,v 1.17 2002/02/28 15:46:33 markus Exp $");
0bc35151	27
	28	#include <openssl/crypto.h>
	29	#include <openssl/bn.h>
	30
	31	#include "xmalloc.h"
	32	#include "buffer.h"
	33	#include "bufaux.h"
	34	#include "key.h"
	35	#include "kex.h"
	36	#include "log.h"
	37	#include "packet.h"
	38	#include "dh.h"
	39	#include "ssh2.h"
91885a4d	40	#include "monitor.h"
	41	#include "monitor_wrap.h"
	42
	43	/* Imports */
	44	extern int use_privsep;
	45	extern int mm_recvfd;
0bc35151	46
396c147e	47	static u_char *
0bc35151	48	kex_dh_hash(
	49	char *client_version_string,
	50	char *server_version_string,
	51	char *ckexinit, int ckexinitlen,
	52	char *skexinit, int skexinitlen,
cf54363d	53	u_char *serverhostkeyblob, int sbloblen,
0bc35151	54	BIGNUM *client_dh_pub,
	55	BIGNUM *server_dh_pub,
	56	BIGNUM *shared_secret)
	57	{
	58	Buffer b;
	59	static u_char digest[EVP_MAX_MD_SIZE];
714954dc	60	const EVP_MD *evp_md = EVP_sha1();
0bc35151	61	EVP_MD_CTX md;
	62
	63	buffer_init(&b);
449c5ba5	64	buffer_put_cstring(&b, client_version_string);
449c5ba5	65	buffer_put_cstring(&b, server_version_string);
0bc35151	66
	67	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
	68	buffer_put_int(&b, ckexinitlen+1);
	69	buffer_put_char(&b, SSH2_MSG_KEXINIT);
	70	buffer_append(&b, ckexinit, ckexinitlen);
	71	buffer_put_int(&b, skexinitlen+1);
	72	buffer_put_char(&b, SSH2_MSG_KEXINIT);
	73	buffer_append(&b, skexinit, skexinitlen);
	74
	75	buffer_put_string(&b, serverhostkeyblob, sbloblen);
	76	buffer_put_bignum2(&b, client_dh_pub);
	77	buffer_put_bignum2(&b, server_dh_pub);
	78	buffer_put_bignum2(&b, shared_secret);
	79
	80	#ifdef DEBUG_KEX
	81	buffer_dump(&b);
	82	#endif
	83	EVP_DigestInit(&md, evp_md);
	84	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	85	EVP_DigestFinal(&md, digest, NULL);
	86
	87	buffer_free(&b);
	88
	89	#ifdef DEBUG_KEX
a209a158	90	dump_digest("hash", digest, EVP_MD_size(evp_md));
0bc35151	91	#endif
	92	return digest;
	93	}
	94
	95	/* client */
	96
396c147e	97	static void
0bc35151	98	kexdh_client(Kex *kex)
	99	{
	100	BIGNUM dh_server_pub = NULL, shared_secret = NULL;
	101	DH *dh;
	102	Key *server_host_key;
cf54363d	103	u_char server_host_key_blob = NULL, signature = NULL;
0bc35151	104	u_char kbuf, hash;
0bc35151	105	u_int klen, kout, slen, sbloblen;
0bc35151	106
	107	/* generate and send 'e', client DH public key */
	108	dh = dh_new_group1();
	109	dh_gen_key(dh, kex->we_need * 8);
	110	packet_start(SSH2_MSG_KEXDH_INIT);
	111	packet_put_bignum2(dh->pub_key);
	112	packet_send();
	113
	114	debug("sending SSH2_MSG_KEXDH_INIT");
	115	#ifdef DEBUG_KEXDH
	116	DHparams_print_fp(stderr, dh);
	117	fprintf(stderr, "pub= ");
	118	BN_print_fp(stderr, dh->pub_key);
	119	fprintf(stderr, "\n");
	120	#endif
	121
	122	debug("expecting SSH2_MSG_KEXDH_REPLY");
54a5250f	123	packet_read_expect(SSH2_MSG_KEXDH_REPLY);
0bc35151	124
	125	/* key, cert */
	126	server_host_key_blob = packet_get_string(&sbloblen);
	127	server_host_key = key_from_blob(server_host_key_blob, sbloblen);
	128	if (server_host_key == NULL)
	129	fatal("cannot decode server_host_key_blob");
215ced77	130	if (server_host_key->type != kex->hostkey_type)
215ced77	131	fatal("type mismatch for decoded server_host_key_blob");
f49bc4f7	132	if (kex->verify_host_key == NULL)
	133	fatal("cannot verify server_host_key");
	134	if (kex->verify_host_key(server_host_key) == -1)
	135	fatal("server_host_key verification failed");
0bc35151	136
0bc35151	137	/* DH paramter f, server public DH key */
b775c6f2	138	if ((dh_server_pub = BN_new()) == NULL)
0bc35151	139	fatal("dh_server_pub == NULL");
20b279e6	140	packet_get_bignum2(dh_server_pub);
0bc35151	141
	142	#ifdef DEBUG_KEXDH
	143	fprintf(stderr, "dh_server_pub= ");
	144	BN_print_fp(stderr, dh_server_pub);
	145	fprintf(stderr, "\n");
	146	debug("bits %d", BN_num_bits(dh_server_pub));
	147	#endif
	148
	149	/* signed H */
	150	signature = packet_get_string(&slen);
95500969	151	packet_check_eom();
0bc35151	152
	153	if (!dh_pub_is_valid(dh, dh_server_pub))
	154	packet_disconnect("bad server public DH value");
	155
	156	klen = DH_size(dh);
	157	kbuf = xmalloc(klen);
	158	kout = DH_compute_key(kbuf, dh_server_pub, dh);
	159	#ifdef DEBUG_KEXDH
	160	dump_digest("shared secret", kbuf, kout);
	161	#endif
b775c6f2	162	if ((shared_secret = BN_new()) == NULL)
b775c6f2	163	fatal("kexdh_client: BN_new failed");
0bc35151	164	BN_bin2bn(kbuf, kout, shared_secret);
	165	memset(kbuf, 0, klen);
	166	xfree(kbuf);
	167
	168	/* calc and verify H */
	169	hash = kex_dh_hash(
	170	kex->client_version_string,
	171	kex->server_version_string,
	172	buffer_ptr(&kex->my), buffer_len(&kex->my),
	173	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	174	server_host_key_blob, sbloblen,
	175	dh->pub_key,
	176	dh_server_pub,
	177	shared_secret
	178	);
	179	xfree(server_host_key_blob);
108d362e	180	BN_clear_free(dh_server_pub);
d8ee838b	181	DH_free(dh);
0bc35151	182
cf54363d	183	if (key_verify(server_host_key, signature, slen, hash, 20) != 1)
0bc35151	184	fatal("key_verify failed for server_host_key");
	185	key_free(server_host_key);
	186	xfree(signature);
	187
	188	/* save session id */
	189	if (kex->session_id == NULL) {
	190	kex->session_id_len = 20;
	191	kex->session_id = xmalloc(kex->session_id_len);
	192	memcpy(kex->session_id, hash, kex->session_id_len);
	193	}
	194
	195	kex_derive_keys(kex, hash, shared_secret);
	196	BN_clear_free(shared_secret);
d8ee838b	197	kex_finish(kex);
0bc35151	198	}
	199
	200	/* server */
	201
396c147e	202	static void
0bc35151	203	kexdh_server(Kex *kex)
	204	{
	205	BIGNUM shared_secret = NULL, dh_client_pub = NULL;
	206	DH *dh;
	207	Key *server_host_key;
	208	u_char kbuf, hash, signature = NULL, server_host_key_blob = NULL;
	209	u_int sbloblen, klen, kout;
c66f9d0e	210	u_int slen;
0bc35151	211
	212	/* generate server DH public key */
	213	dh = dh_new_group1();
	214	dh_gen_key(dh, kex->we_need * 8);
	215
	216	debug("expecting SSH2_MSG_KEXDH_INIT");
54a5250f	217	packet_read_expect(SSH2_MSG_KEXDH_INIT);
0bc35151	218
	219	if (kex->load_host_key == NULL)
	220	fatal("Cannot load hostkey");
	221	server_host_key = kex->load_host_key(kex->hostkey_type);
	222	if (server_host_key == NULL)
	223	fatal("Unsupported hostkey type %d", kex->hostkey_type);
	224
	225	/* key, cert */
b775c6f2	226	if ((dh_client_pub = BN_new()) == NULL)
0bc35151	227	fatal("dh_client_pub == NULL");
20b279e6	228	packet_get_bignum2(dh_client_pub);
b967d870	229	packet_check_eom();
0bc35151	230
	231	#ifdef DEBUG_KEXDH
	232	fprintf(stderr, "dh_client_pub= ");
	233	BN_print_fp(stderr, dh_client_pub);
	234	fprintf(stderr, "\n");
	235	debug("bits %d", BN_num_bits(dh_client_pub));
	236	#endif
	237
	238	#ifdef DEBUG_KEXDH
	239	DHparams_print_fp(stderr, dh);
	240	fprintf(stderr, "pub= ");
	241	BN_print_fp(stderr, dh->pub_key);
	242	fprintf(stderr, "\n");
	243	#endif
	244	if (!dh_pub_is_valid(dh, dh_client_pub))
	245	packet_disconnect("bad client public DH value");
	246
	247	klen = DH_size(dh);
	248	kbuf = xmalloc(klen);
	249	kout = DH_compute_key(kbuf, dh_client_pub, dh);
	250	#ifdef DEBUG_KEXDH
	251	dump_digest("shared secret", kbuf, kout);
	252	#endif
b775c6f2	253	if ((shared_secret = BN_new()) == NULL)
b775c6f2	254	fatal("kexdh_server: BN_new failed");
0bc35151	255	BN_bin2bn(kbuf, kout, shared_secret);
	256	memset(kbuf, 0, klen);
	257	xfree(kbuf);
	258
	259	key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);
	260
	261	/* calc H */
	262	hash = kex_dh_hash(
	263	kex->client_version_string,
	264	kex->server_version_string,
	265	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	266	buffer_ptr(&kex->my), buffer_len(&kex->my),
cf54363d	267	server_host_key_blob, sbloblen,
0bc35151	268	dh_client_pub,
	269	dh->pub_key,
	270	shared_secret
	271	);
108d362e	272	BN_clear_free(dh_client_pub);
0bc35151	273
	274	/* save session id := H */
	275	/* XXX hashlen depends on KEX */
	276	if (kex->session_id == NULL) {
	277	kex->session_id_len = 20;
	278	kex->session_id = xmalloc(kex->session_id_len);
	279	memcpy(kex->session_id, hash, kex->session_id_len);
	280	}
	281
	282	/* sign H */
	283	/* XXX hashlen depends on KEX */
91885a4d	284	if (use_privsep)
	285	mm_key_sign(mm_recvfd,
	286	kex->host_key_index(server_host_key),
	287	&signature, &slen, hash, 20);
	288	else
	289	key_sign(server_host_key, &signature, &slen, hash, 20);
0bc35151	290
	291	/* destroy_sensitive_data(); */
	292
	293	/* send server hostkey, DH pubkey 'f' and singed H */
	294	packet_start(SSH2_MSG_KEXDH_REPLY);
cf54363d	295	packet_put_string(server_host_key_blob, sbloblen);
0bc35151	296	packet_put_bignum2(dh->pub_key); /* f */
cf54363d	297	packet_put_string(signature, slen);
0bc35151	298	packet_send();
d8ee838b	299
0bc35151	300	xfree(signature);
0bc35151	301	xfree(server_host_key_blob);
d8ee838b	302	/* have keys, free DH */
d8ee838b	303	DH_free(dh);
0bc35151	304
	305	kex_derive_keys(kex, hash, shared_secret);
	306	BN_clear_free(shared_secret);
d8ee838b	307	kex_finish(kex);
0bc35151	308	}
	309
	310	void
	311	kexdh(Kex *kex)
	312	{
	313	if (kex->server)
	314	kexdh_server(kex);
	315	else
	316	kexdh_client(kex);
	317	}