[openssh.git] / kex.c

/*
 * Copyright (c) 2000 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: kex.c,v 1.30 2001/04/04 20:25:37 markus Exp $");

#include <openssl/crypto.h>

#include "ssh2.h"
#include "xmalloc.h"
#include "buffer.h"
#include "bufaux.h"
#include "packet.h"
#include "compat.h"
#include "cipher.h"
#include "kex.h"
#include "key.h"
#include "log.h"
#include "mac.h"
#include "match.h"
#include "dispatch.h"

#define KEX_COOKIE_LEN	16

void	kex_kexinit_finish(Kex *kex);
void	kex_choose_conf(Kex *k);

/* put algorithm proposal into buffer */
void
kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
{
	u_int32_t rand = 0;
	int i;

	buffer_clear(b);
	for (i = 0; i < KEX_COOKIE_LEN; i++) {
		if (i % 4 == 0)
			rand = arc4random();
		buffer_put_char(b, rand & 0xff);
		rand >>= 8;
	}
	for (i = 0; i < PROPOSAL_MAX; i++)
		buffer_put_cstring(b, proposal[i]);
	buffer_put_char(b, 0);			/* first_kex_packet_follows */
	buffer_put_int(b, 0);			/* uint32 reserved */
}

/* parse buffer and return algorithm proposal */
char **
kex_buf2prop(Buffer *raw)
{
	Buffer b;
	int i;
	char **proposal;

	proposal = xmalloc(PROPOSAL_MAX * sizeof(char *));

	buffer_init(&b);
	buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
	/* skip cookie */
	for (i = 0; i < KEX_COOKIE_LEN; i++)
		buffer_get_char(&b);
	/* extract kex init proposal strings */
	for (i = 0; i < PROPOSAL_MAX; i++) {
		proposal[i] = buffer_get_string(&b,NULL);
		debug2("kex_parse_kexinit: %s", proposal[i]);
	}
	/* first kex follows / reserved */
	i = buffer_get_char(&b);
	debug2("kex_parse_kexinit: first_kex_follows %d ", i);
	i = buffer_get_int(&b);
	debug2("kex_parse_kexinit: reserved %d ", i);
	buffer_free(&b);
	return proposal;
}

void
kex_prop_free(char **proposal)
{
	int i;

	for (i = 0; i < PROPOSAL_MAX; i++)
		xfree(proposal[i]);
	xfree(proposal);
}

void
kex_protocol_error(int type, int plen, void *ctxt)
{
        error("Hm, kex protocol error: type %d plen %d", type, plen);
}

void
kex_clear_dispatch(void)
{
	int i;

	/* Numbers 30-49 are used for kex packets */
	for (i = 30; i <= 49; i++)
		dispatch_set(i, &kex_protocol_error);
}

void
kex_finish(Kex *kex)
{
	int plen;

	kex_clear_dispatch();

	packet_start(SSH2_MSG_NEWKEYS);
	packet_send();
	/* packet_write_wait(); */
	debug("SSH2_MSG_NEWKEYS sent");

        debug("waiting for SSH2_MSG_NEWKEYS");
        packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
	debug("SSH2_MSG_NEWKEYS received");
	kex->done = 1;
	buffer_clear(&kex->peer);
	/* buffer_clear(&kex->my); */
	kex->flags &= ~KEX_INIT_SENT;
}

void
kex_send_kexinit(Kex *kex)
{
	if (kex == NULL) {
		error("kex_send_kexinit: no kex, cannot rekey");
		return;
	}
	if (kex->flags & KEX_INIT_SENT) {
		debug("KEX_INIT_SENT");
		return;
	}
	kex->done = 0;
	packet_start(SSH2_MSG_KEXINIT);
	packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
	packet_send();
	debug("SSH2_MSG_KEXINIT sent");
	kex->flags |= KEX_INIT_SENT;
}

void
kex_input_kexinit(int type, int plen, void *ctxt)
{
	char *ptr;
	int dlen;
	Kex *kex = (Kex *)ctxt;

	debug("SSH2_MSG_KEXINIT received");
	if (kex == NULL)
		fatal("kex_input_kexinit: no kex, cannot rekey");

	ptr = packet_get_raw(&dlen);
	buffer_append(&kex->peer, ptr, dlen);

	kex_kexinit_finish(kex);
}

Kex *
kex_setup(char *proposal[PROPOSAL_MAX])
{
	Kex *kex;

	kex = xmalloc(sizeof(*kex));
	memset(kex, 0, sizeof(*kex));
	buffer_init(&kex->peer);
	buffer_init(&kex->my);
	kex_prop2buf(&kex->my, proposal);
	kex->done = 0;

	kex_send_kexinit(kex);					/* we start */
	kex_clear_dispatch();
	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);

	return kex;
}

void
kex_kexinit_finish(Kex *kex)
{
	if (!(kex->flags & KEX_INIT_SENT))
		kex_send_kexinit(kex);

	kex_choose_conf(kex);

	switch(kex->kex_type) {
	case DH_GRP1_SHA1:
		kexdh(kex);
		break;
	case DH_GEX_SHA1:
		kexgex(kex);
		break;
	default:
		fatal("Unsupported key exchange %d", kex->kex_type);
	}
}

void
choose_enc(Enc *enc, char *client, char *server)
{
	char *name = match_list(client, server, NULL);
	if (name == NULL)
		fatal("no matching cipher found: client %s server %s", client, server);
	enc->cipher = cipher_by_name(name);
	if (enc->cipher == NULL)
		fatal("matching cipher is not supported: %s", name);
	enc->name = name;
	enc->enabled = 0;
	enc->iv = NULL;
	enc->key = NULL;
}
void
choose_mac(Mac *mac, char *client, char *server)
{
	char *name = match_list(client, server, NULL);
	if (name == NULL)
		fatal("no matching mac found: client %s server %s", client, server);
	if (mac_init(mac, name) < 0)
		fatal("unsupported mac %s", name);
	/* truncate the key */
	if (datafellows & SSH_BUG_HMAC)
		mac->key_len = 16;
	mac->name = name;
	mac->key = NULL;
	mac->enabled = 0;
}
void
choose_comp(Comp *comp, char *client, char *server)
{
	char *name = match_list(client, server, NULL);
	if (name == NULL)
		fatal("no matching comp found: client %s server %s", client, server);
	if (strcmp(name, "zlib") == 0) {
		comp->type = 1;
	} else if (strcmp(name, "none") == 0) {
		comp->type = 0;
	} else {
		fatal("unsupported comp %s", name);
	}
	comp->name = name;
}
void
choose_kex(Kex *k, char *client, char *server)
{
	k->name = match_list(client, server, NULL);
	if (k->name == NULL)
		fatal("no kex alg");
	if (strcmp(k->name, KEX_DH1) == 0) {
		k->kex_type = DH_GRP1_SHA1;
	} else if (strcmp(k->name, KEX_DHGEX) == 0) {
		k->kex_type = DH_GEX_SHA1;
	} else
		fatal("bad kex alg %s", k->name);
}
void
choose_hostkeyalg(Kex *k, char *client, char *server)
{
	char *hostkeyalg = match_list(client, server, NULL);
	if (hostkeyalg == NULL)
		fatal("no hostkey alg");
	k->hostkey_type = key_type_from_name(hostkeyalg);
	if (k->hostkey_type == KEY_UNSPEC)
		fatal("bad hostkey alg '%s'", hostkeyalg);
	xfree(hostkeyalg);
}

void
kex_choose_conf(Kex *kex)
{
	Newkeys *newkeys;
	char **my, **peer;
	char **cprop, **sprop;
	int nenc, nmac, ncomp;
	int mode;
	int ctos;				/* direction: if true client-to-server */
	int need;

	my   = kex_buf2prop(&kex->my);
	peer = kex_buf2prop(&kex->peer);

	if (kex->server) {
		cprop=peer;
		sprop=my;
	} else {
		cprop=my;
		sprop=peer;
	}

	/* Algorithm Negotiation */
	for (mode = 0; mode < MODE_MAX; mode++) {
		newkeys = xmalloc(sizeof(*newkeys));
		memset(newkeys, 0, sizeof(*newkeys));
		kex->newkeys[mode] = newkeys;
		ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
		nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
		nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
		ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
		choose_enc (&newkeys->enc,  cprop[nenc],  sprop[nenc]);
		choose_mac (&newkeys->mac,  cprop[nmac],  sprop[nmac]);
		choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
		debug("kex: %s %s %s %s",
		    ctos ? "client->server" : "server->client",
		    newkeys->enc.name,
		    newkeys->mac.name,
		    newkeys->comp.name);
	}
	choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
	choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
	    sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
	need = 0;
	for (mode = 0; mode < MODE_MAX; mode++) {
		newkeys = kex->newkeys[mode];
		if (need < newkeys->enc.cipher->key_len)
			need = newkeys->enc.cipher->key_len;
		if (need < newkeys->enc.cipher->block_size)
			need = newkeys->enc.cipher->block_size;
		if (need < newkeys->mac.key_len)
			need = newkeys->mac.key_len;
	}
	/* XXX need runden? */
	kex->we_need = need;

	kex_prop_free(my);
	kex_prop_free(peer);
}

u_char *
derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
{
	Buffer b;
	EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	char c = id;
	int have;
	int mdsz = evp_md->md_size;
	u_char *digest = xmalloc(roundup(need, mdsz));

	buffer_init(&b);
	buffer_put_bignum2(&b, shared_secret);

	/* K1 = HASH(K || H || "A" || session_id) */
	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	EVP_DigestUpdate(&md, hash, mdsz);
	EVP_DigestUpdate(&md, &c, 1);
	EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
	EVP_DigestFinal(&md, digest, NULL);

	/*
	 * expand key:
	 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
	 * Key = K1 || K2 || ... || Kn
	 */
	for (have = mdsz; need > have; have += mdsz) {
		EVP_DigestInit(&md, evp_md);
		EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
		EVP_DigestUpdate(&md, hash, mdsz);
		EVP_DigestUpdate(&md, digest, have);
		EVP_DigestFinal(&md, digest + have, NULL);
	}
	buffer_free(&b);
#ifdef DEBUG_KEX
	fprintf(stderr, "key '%c'== ", c);
	dump_digest("key", digest, need);
#endif
	return digest;
}

Newkeys *current_keys[MODE_MAX];

#define NKEYS	6
void
kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
{
	u_char *keys[NKEYS];
	int i, mode, ctos;

	for (i = 0; i < NKEYS; i++)
		keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);

	debug("kex_derive_keys");
	for (mode = 0; mode < MODE_MAX; mode++) {
		current_keys[mode] = kex->newkeys[mode];
		kex->newkeys[mode] = NULL;
		ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
		current_keys[mode]->enc.iv  = keys[ctos ? 0 : 1];
		current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
		current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
	}
}

Newkeys *
kex_get_newkeys(int mode)
{
	Newkeys *ret;

	ret = current_keys[mode];
	current_keys[mode] = NULL;
	return ret;
}

#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
void
dump_digest(char *msg, u_char *digest, int len)
{
	int i;

	fprintf(stderr, "%s\n", msg);
	for (i = 0; i< len; i++){
		fprintf(stderr, "%02x", digest[i]);
		if (i%32 == 31)
			fprintf(stderr, "\n");
		else if (i%8 == 7)
			fprintf(stderr, " ");
	}
	fprintf(stderr, "\n");
}
#endif
Commit	Line	Data
4f8c6159	1	/*
	2	* Copyright (c) 2000 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.
4f8c6159	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"
c422989b	26	RCSID("$OpenBSD: kex.c,v 1.30 2001/04/04 20:25:37 markus Exp $");
4f8c6159	27
4f8c6159	28	#include <openssl/crypto.h>
4f8c6159	29
42f11eb2	30	#include "ssh2.h"
	31	#include "xmalloc.h"
	32	#include "buffer.h"
	33	#include "bufaux.h"
	34	#include "packet.h"
	35	#include "compat.h"
	36	#include "cipher.h"
4f8c6159	37	#include "kex.h"
fa08c86b	38	#include "key.h"
42f11eb2	39	#include "log.h"
b2552997	40	#include "mac.h"
cab80f75	41	#include "match.h"
a5c9ffdb	42	#include "dispatch.h"
4f8c6159	43
71276795	44	#define KEX_COOKIE_LEN 16
71276795	45
a5c9ffdb	46	void kex_kexinit_finish(Kex *kex);
	47	void kex_choose_conf(Kex *k);
	48
	49	/* put algorithm proposal into buffer */
	50	void
	51	kex_prop2buf(Buffer b, char proposal[PROPOSAL_MAX])
4f8c6159	52	{
4f8c6159	53	u_int32_t rand = 0;
4f8c6159	54	int i;
a5c9ffdb	55
a5c9ffdb	56	buffer_clear(b);
71276795	57	for (i = 0; i < KEX_COOKIE_LEN; i++) {
4f8c6159	58	if (i % 4 == 0)
4f8c6159	59	rand = arc4random();
a5c9ffdb	60	buffer_put_char(b, rand & 0xff);
4f8c6159	61	rand >>= 8;
4f8c6159	62	}
4f8c6159	63	for (i = 0; i < PROPOSAL_MAX; i++)
a5c9ffdb	64	buffer_put_cstring(b, proposal[i]);
	65	buffer_put_char(b, 0); /* first_kex_packet_follows */
	66	buffer_put_int(b, 0); /* uint32 reserved */
4f8c6159	67	}
4f8c6159	68
a5c9ffdb	69	/* parse buffer and return algorithm proposal */
	70	char **
	71	kex_buf2prop(Buffer *raw)
71276795	72	{
a5c9ffdb	73	Buffer b;
71276795	74	int i;
a5c9ffdb	75	char **proposal;
71276795	76
a5c9ffdb	77	proposal = xmalloc(PROPOSAL_MAX * sizeof(char *));
	78
	79	buffer_init(&b);
	80	buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
71276795	81	/* skip cookie */
71276795	82	for (i = 0; i < KEX_COOKIE_LEN; i++)
a5c9ffdb	83	buffer_get_char(&b);
71276795	84	/* extract kex init proposal strings */
71276795	85	for (i = 0; i < PROPOSAL_MAX; i++) {
a5c9ffdb	86	proposal[i] = buffer_get_string(&b,NULL);
a5c9ffdb	87	debug2("kex_parse_kexinit: %s", proposal[i]);
71276795	88	}
a5c9ffdb	89	/* first kex follows / reserved */
	90	i = buffer_get_char(&b);
	91	debug2("kex_parse_kexinit: first_kex_follows %d ", i);
	92	i = buffer_get_int(&b);
	93	debug2("kex_parse_kexinit: reserved %d ", i);
	94	buffer_free(&b);
	95	return proposal;
71276795	96	}
71276795	97
4f8c6159	98	void
a5c9ffdb	99	kex_prop_free(char **proposal)
4f8c6159	100	{
4f8c6159	101	int i;
a5c9ffdb	102
	103	for (i = 0; i < PROPOSAL_MAX; i++)
	104	xfree(proposal[i]);
	105	xfree(proposal);
4f8c6159	106	}
4f8c6159	107
a5c9ffdb	108	void
a5c9ffdb	109	kex_protocol_error(int type, int plen, void *ctxt)
4f8c6159	110	{
a5c9ffdb	111	error("Hm, kex protocol error: type %d plen %d", type, plen);
a5c9ffdb	112	}
4f8c6159	113
7a37c112	114	void
	115	kex_clear_dispatch(void)
	116	{
	117	int i;
	118
	119	/* Numbers 30-49 are used for kex packets */
	120	for (i = 30; i <= 49; i++)
	121	dispatch_set(i, &kex_protocol_error);
	122	}
	123
a5c9ffdb	124	void
d8ee838b	125	kex_finish(Kex *kex)
a5c9ffdb	126	{
7a37c112	127	int plen;
	128
	129	kex_clear_dispatch();
d8ee838b	130
a5c9ffdb	131	packet_start(SSH2_MSG_NEWKEYS);
	132	packet_send();
	133	/* packet_write_wait(); */
	134	debug("SSH2_MSG_NEWKEYS sent");
4f8c6159	135
d8ee838b	136	debug("waiting for SSH2_MSG_NEWKEYS");
d8ee838b	137	packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
a5c9ffdb	138	debug("SSH2_MSG_NEWKEYS received");
c422989b	139	kex->done = 1;
a5c9ffdb	140	buffer_clear(&kex->peer);
d1ac6175	141	/* buffer_clear(&kex->my); */
a5c9ffdb	142	kex->flags &= ~KEX_INIT_SENT;
4f8c6159	143	}
4f8c6159	144
a5c9ffdb	145	void
a5c9ffdb	146	kex_send_kexinit(Kex *kex)
94ec8c6b	147	{
7a37c112	148	if (kex == NULL) {
	149	error("kex_send_kexinit: no kex, cannot rekey");
	150	return;
	151	}
d8ee838b	152	if (kex->flags & KEX_INIT_SENT) {
	153	debug("KEX_INIT_SENT");
	154	return;
	155	}
c422989b	156	kex->done = 0;
a5c9ffdb	157	packet_start(SSH2_MSG_KEXINIT);
	158	packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
	159	packet_send();
	160	debug("SSH2_MSG_KEXINIT sent");
	161	kex->flags \|= KEX_INIT_SENT;
	162	}
2b87da3b	163
a5c9ffdb	164	void
	165	kex_input_kexinit(int type, int plen, void *ctxt)
	166	{
	167	char *ptr;
	168	int dlen;
	169	Kex kex = (Kex )ctxt;
94ec8c6b	170
a5c9ffdb	171	debug("SSH2_MSG_KEXINIT received");
7a37c112	172	if (kex == NULL)
7a37c112	173	fatal("kex_input_kexinit: no kex, cannot rekey");
94ec8c6b	174
a5c9ffdb	175	ptr = packet_get_raw(&dlen);
a5c9ffdb	176	buffer_append(&kex->peer, ptr, dlen);
94ec8c6b	177
a5c9ffdb	178	kex_kexinit_finish(kex);
94ec8c6b	179	}
94ec8c6b	180
a5c9ffdb	181	Kex *
d8ee838b	182	kex_setup(char *proposal[PROPOSAL_MAX])
4f8c6159	183	{
a5c9ffdb	184	Kex *kex;
4f8c6159	185
a5c9ffdb	186	kex = xmalloc(sizeof(*kex));
	187	memset(kex, 0, sizeof(*kex));
	188	buffer_init(&kex->peer);
	189	buffer_init(&kex->my);
	190	kex_prop2buf(&kex->my, proposal);
c422989b	191	kex->done = 0;
a5c9ffdb	192
a5c9ffdb	193	kex_send_kexinit(kex); /* we start */
7a37c112	194	kex_clear_dispatch();
a5c9ffdb	195	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
7a37c112	196
a5c9ffdb	197	return kex;
a5c9ffdb	198	}
4f8c6159	199
a5c9ffdb	200	void
	201	kex_kexinit_finish(Kex *kex)
	202	{
	203	if (!(kex->flags & KEX_INIT_SENT))
	204	kex_send_kexinit(kex);
	205
	206	kex_choose_conf(kex);
	207
	208	switch(kex->kex_type) {
	209	case DH_GRP1_SHA1:
	210	kexdh(kex);
	211	break;
	212	case DH_GEX_SHA1:
	213	kexgex(kex);
	214	break;
	215	default:
	216	fatal("Unsupported key exchange %d", kex->kex_type);
4f8c6159	217	}
4f8c6159	218	}
4f8c6159	219
4f8c6159	220	void
	221	choose_enc(Enc enc, char client, char *server)
	222	{
cab80f75	223	char *name = match_list(client, server, NULL);
4f8c6159	224	if (name == NULL)
4f8c6159	225	fatal("no matching cipher found: client %s server %s", client, server);
94ec8c6b	226	enc->cipher = cipher_by_name(name);
	227	if (enc->cipher == NULL)
	228	fatal("matching cipher is not supported: %s", name);
4f8c6159	229	enc->name = name;
	230	enc->enabled = 0;
	231	enc->iv = NULL;
	232	enc->key = NULL;
	233	}
	234	void
	235	choose_mac(Mac mac, char client, char *server)
	236	{
cab80f75	237	char *name = match_list(client, server, NULL);
4f8c6159	238	if (name == NULL)
4f8c6159	239	fatal("no matching mac found: client %s server %s", client, server);
b2552997	240	if (mac_init(mac, name) < 0)
4f8c6159	241	fatal("unsupported mac %s", name);
b2552997	242	/* truncate the key */
	243	if (datafellows & SSH_BUG_HMAC)
	244	mac->key_len = 16;
4f8c6159	245	mac->name = name;
4f8c6159	246	mac->key = NULL;
	247	mac->enabled = 0;
	248	}
	249	void
	250	choose_comp(Comp comp, char client, char *server)
	251	{
cab80f75	252	char *name = match_list(client, server, NULL);
4f8c6159	253	if (name == NULL)
	254	fatal("no matching comp found: client %s server %s", client, server);
	255	if (strcmp(name, "zlib") == 0) {
	256	comp->type = 1;
	257	} else if (strcmp(name, "none") == 0) {
	258	comp->type = 0;
	259	} else {
	260	fatal("unsupported comp %s", name);
	261	}
	262	comp->name = name;
	263	}
	264	void
	265	choose_kex(Kex k, char client, char *server)
	266	{
cab80f75	267	k->name = match_list(client, server, NULL);
4f8c6159	268	if (k->name == NULL)
4f8c6159	269	fatal("no kex alg");
94ec8c6b	270	if (strcmp(k->name, KEX_DH1) == 0) {
	271	k->kex_type = DH_GRP1_SHA1;
	272	} else if (strcmp(k->name, KEX_DHGEX) == 0) {
	273	k->kex_type = DH_GEX_SHA1;
	274	} else
4f8c6159	275	fatal("bad kex alg %s", k->name);
	276	}
	277	void
	278	choose_hostkeyalg(Kex k, char client, char *server)
	279	{
cab80f75	280	char *hostkeyalg = match_list(client, server, NULL);
fa08c86b	281	if (hostkeyalg == NULL)
4f8c6159	282	fatal("no hostkey alg");
fa08c86b	283	k->hostkey_type = key_type_from_name(hostkeyalg);
	284	if (k->hostkey_type == KEY_UNSPEC)
	285	fatal("bad hostkey alg '%s'", hostkeyalg);
eea39c02	286	xfree(hostkeyalg);
4f8c6159	287	}
4f8c6159	288
a5c9ffdb	289	void
d1ac6175	290	kex_choose_conf(Kex *kex)
4f8c6159	291	{
d1ac6175	292	Newkeys *newkeys;
a5c9ffdb	293	char my, peer;
a5c9ffdb	294	char cprop, sprop;
d1ac6175	295	int nenc, nmac, ncomp;
4f8c6159	296	int mode;
	297	int ctos; /* direction: if true client-to-server */
	298	int need;
4f8c6159	299
d1ac6175	300	my = kex_buf2prop(&kex->my);
d1ac6175	301	peer = kex_buf2prop(&kex->peer);
a5c9ffdb	302
d1ac6175	303	if (kex->server) {
a5c9ffdb	304	cprop=peer;
	305	sprop=my;
	306	} else {
	307	cprop=my;
	308	sprop=peer;
	309	}
4f8c6159	310
c422989b	311	/* Algorithm Negotiation */
4f8c6159	312	for (mode = 0; mode < MODE_MAX; mode++) {
d1ac6175	313	newkeys = xmalloc(sizeof(*newkeys));
d1ac6175	314	memset(newkeys, 0, sizeof(*newkeys));
c422989b	315	kex->newkeys[mode] = newkeys;
d1ac6175	316	ctos = (!kex->server && mode == MODE_OUT) \|\| (kex->server && mode == MODE_IN);
4f8c6159	317	nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
	318	nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
	319	ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
d1ac6175	320	choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]);
	321	choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]);
	322	choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
4f8c6159	323	debug("kex: %s %s %s %s",
4f8c6159	324	ctos ? "client->server" : "server->client",
d1ac6175	325	newkeys->enc.name,
	326	newkeys->mac.name,
	327	newkeys->comp.name);
4f8c6159	328	}
d1ac6175	329	choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
d1ac6175	330	choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
4f8c6159	331	sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
4f8c6159	332	need = 0;
4f8c6159	333	for (mode = 0; mode < MODE_MAX; mode++) {
c422989b	334	newkeys = kex->newkeys[mode];
d1ac6175	335	if (need < newkeys->enc.cipher->key_len)
	336	need = newkeys->enc.cipher->key_len;
	337	if (need < newkeys->enc.cipher->block_size)
	338	need = newkeys->enc.cipher->block_size;
	339	if (need < newkeys->mac.key_len)
	340	need = newkeys->mac.key_len;
4f8c6159	341	}
71276795	342	/* XXX need runden? */
d1ac6175	343	kex->we_need = need;
a5c9ffdb	344
	345	kex_prop_free(my);
	346	kex_prop_free(peer);
a5c9ffdb	347	}
	348
	349	u_char *
d1ac6175	350	derive_key(Kex kex, int id, int need, u_char hash, BIGNUM *shared_secret)
a5c9ffdb	351	{
	352	Buffer b;
	353	EVP_MD *evp_md = EVP_sha1();
	354	EVP_MD_CTX md;
	355	char c = id;
	356	int have;
	357	int mdsz = evp_md->md_size;
c422989b	358	u_char *digest = xmalloc(roundup(need, mdsz));
a5c9ffdb	359
	360	buffer_init(&b);
	361	buffer_put_bignum2(&b, shared_secret);
	362
c422989b	363	/* K1 = HASH(K \|\| H \|\| "A" \|\| session_id) */
a5c9ffdb	364	EVP_DigestInit(&md, evp_md);
c422989b	365	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	366	EVP_DigestUpdate(&md, hash, mdsz);
	367	EVP_DigestUpdate(&md, &c, 1);
d1ac6175	368	EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
a5c9ffdb	369	EVP_DigestFinal(&md, digest, NULL);
a5c9ffdb	370
c422989b	371	/*
	372	* expand key:
	373	* Kn = HASH(K \|\| H \|\| K1 \|\| K2 \|\| ... \|\| Kn-1)
	374	* Key = K1 \|\| K2 \|\| ... \|\| Kn
	375	*/
a5c9ffdb	376	for (have = mdsz; need > have; have += mdsz) {
	377	EVP_DigestInit(&md, evp_md);
	378	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	379	EVP_DigestUpdate(&md, hash, mdsz);
	380	EVP_DigestUpdate(&md, digest, have);
	381	EVP_DigestFinal(&md, digest + have, NULL);
	382	}
	383	buffer_free(&b);
	384	#ifdef DEBUG_KEX
	385	fprintf(stderr, "key '%c'== ", c);
	386	dump_digest("key", digest, need);
	387	#endif
	388	return digest;
4f8c6159	389	}
4f8c6159	390
c422989b	391	Newkeys *current_keys[MODE_MAX];
d1ac6175	392
cab80f75	393	#define NKEYS 6
a5c9ffdb	394	void
d1ac6175	395	kex_derive_keys(Kex kex, u_char hash, BIGNUM *shared_secret)
4f8c6159	396	{
1e3b8b07	397	u_char *keys[NKEYS];
d1ac6175	398	int i, mode, ctos;
4f8c6159	399
4f8c6159	400	for (i = 0; i < NKEYS; i++)
d1ac6175	401	keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
4f8c6159	402
d1ac6175	403	debug("kex_derive_keys");
4f8c6159	404	for (mode = 0; mode < MODE_MAX; mode++) {
c422989b	405	current_keys[mode] = kex->newkeys[mode];
c422989b	406	kex->newkeys[mode] = NULL;
d1ac6175	407	ctos = (!kex->server && mode == MODE_OUT) \|\| (kex->server && mode == MODE_IN);
c422989b	408	current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
	409	current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
	410	current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
4f8c6159	411	}
4f8c6159	412	}
a5c9ffdb	413
d1ac6175	414	Newkeys *
	415	kex_get_newkeys(int mode)
	416	{
c422989b	417	Newkeys *ret;
	418
	419	ret = current_keys[mode];
	420	current_keys[mode] = NULL;
	421	return ret;
d1ac6175	422	}
d1ac6175	423
a5c9ffdb	424	#if defined(DEBUG_KEX) \|\| defined(DEBUG_KEXDH)
	425	void
	426	dump_digest(char msg, u_char digest, int len)
	427	{
	428	int i;
	429
	430	fprintf(stderr, "%s\n", msg);
	431	for (i = 0; i< len; i++){
	432	fprintf(stderr, "%02x", digest[i]);
	433	if (i%32 == 31)
	434	fprintf(stderr, "\n");
	435	else if (i%8 == 7)
	436	fprintf(stderr, " ");
	437	}
	438	fprintf(stderr, "\n");
	439	}
	440	#endif