[gssapi-openssh.git] / openssh / kex.c

/*
 * Copyright (c) 2000, 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: kex.c,v 1.50 2002/05/15 15:47:49 mouring 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"
#include "monitor.h"

#define KEX_COOKIE_LEN	16

/* Use privilege separation for sshd */
int use_privsep;
struct monitor *pmonitor;


/* prototype */
static void kex_kexinit_finish(Kex *);
static void kex_choose_conf(Kex *);

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

	buffer_clear(b);
	/*
	 * add a dummy cookie, the cookie will be overwritten by
	 * kex_send_kexinit(), each time a kexinit is set
	 */
	for (i = 0; i < KEX_COOKIE_LEN; i++)
		buffer_put_char(b, 0);
	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 */
static 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;
}

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

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

static void
kex_protocol_error(int type, u_int32_t seq, void *ctxt)
{
	error("Hm, kex protocol error: type %d seq %u", type, seq);
}

static void
kex_reset_dispatch(void)
{
	dispatch_range(SSH2_MSG_TRANSPORT_MIN,
	    SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
}

void
kex_finish(Kex *kex)
{
	kex_reset_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(SSH2_MSG_NEWKEYS);
	packet_check_eom();
	debug("SSH2_MSG_NEWKEYS received");

	kex->done = 1;
	buffer_clear(&kex->peer);
	/* buffer_clear(&kex->my); */
	kex->flags &= ~KEX_INIT_SENT;
	xfree(kex->name);
	kex->name = NULL;
}

void
kex_send_kexinit(Kex *kex)
{
	u_int32_t rand = 0;
	u_char *cookie;
	int i;

	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;

	/* generate a random cookie */
	if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
		fatal("kex_send_kexinit: kex proposal too short");
	cookie = buffer_ptr(&kex->my);
	for (i = 0; i < KEX_COOKIE_LEN; i++) {
		if (i % 4 == 0)
			rand = arc4random();
		cookie[i] = rand;
		rand >>= 8;
	}
	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, u_int32_t seq, void *ctxt)
{
	char *ptr;
	int dlen;
	int i;
	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);

	/* discard packet */
	for (i = 0; i < KEX_COOKIE_LEN; i++)
		packet_get_char();
	for (i = 0; i < PROPOSAL_MAX; i++)
		xfree(packet_get_string(NULL));
	packet_get_char();
	packet_get_int();
	packet_check_eom();

	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_reset_dispatch();

	return kex;
}

static 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);
	}
}

static 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);
	if ((enc->cipher = cipher_by_name(name)) == NULL)
		fatal("matching cipher is not supported: %s", name);
	enc->name = name;
	enc->enabled = 0;
	enc->iv = NULL;
	enc->key = NULL;
	enc->key_len = cipher_keylen(enc->cipher);
	enc->block_size = cipher_blocksize(enc->cipher);
}
static 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;
}
static 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;
}
static 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);
}
static 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);
}

static 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.key_len)
			need = newkeys->enc.key_len;
		if (need < newkeys->enc.block_size)
			need = newkeys->enc.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);
}

static u_char *
derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
{
	Buffer b;
	const EVP_MD *evp_md = EVP_sha1();
	EVP_MD_CTX md;
	char c = id;
	int have;
	int mdsz = EVP_MD_size(evp_md);
	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);
	if (!(datafellows & SSH_BUG_DERIVEKEY))
		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);
		if (!(datafellows & SSH_BUG_DERIVEKEY))
			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
3c0ef626	1	/*
	2	* Copyright (c) 2000, 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"
700318f3	26	RCSID("$OpenBSD: kex.c,v 1.50 2002/05/15 15:47:49 mouring Exp $");
3c0ef626	27
	28	#include <openssl/crypto.h>
	29
	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"
	37	#include "kex.h"
	38	#include "key.h"
	39	#include "log.h"
	40	#include "mac.h"
	41	#include "match.h"
	42	#include "dispatch.h"
700318f3	43	#include "monitor.h"
3c0ef626	44
	45	#define KEX_COOKIE_LEN 16
	46
700318f3	47	/* Use privilege separation for sshd */
	48	int use_privsep;
	49	struct monitor *pmonitor;
	50
	51
3c0ef626	52	/* prototype */
	53	static void kex_kexinit_finish(Kex *);
	54	static void kex_choose_conf(Kex *);
	55
	56	/* put algorithm proposal into buffer */
	57	static void
	58	kex_prop2buf(Buffer b, char proposal[PROPOSAL_MAX])
	59	{
3c0ef626	60	int i;
	61
	62	buffer_clear(b);
700318f3	63	/*
	64	* add a dummy cookie, the cookie will be overwritten by
	65	* kex_send_kexinit(), each time a kexinit is set
	66	*/
	67	for (i = 0; i < KEX_COOKIE_LEN; i++)
	68	buffer_put_char(b, 0);
3c0ef626	69	for (i = 0; i < PROPOSAL_MAX; i++)
	70	buffer_put_cstring(b, proposal[i]);
	71	buffer_put_char(b, 0); /* first_kex_packet_follows */
	72	buffer_put_int(b, 0); /* uint32 reserved */
	73	}
	74
	75	/* parse buffer and return algorithm proposal */
	76	static char **
	77	kex_buf2prop(Buffer *raw)
	78	{
	79	Buffer b;
	80	int i;
	81	char **proposal;
	82
	83	proposal = xmalloc(PROPOSAL_MAX * sizeof(char *));
	84
	85	buffer_init(&b);
	86	buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
	87	/* skip cookie */
	88	for (i = 0; i < KEX_COOKIE_LEN; i++)
	89	buffer_get_char(&b);
	90	/* extract kex init proposal strings */
	91	for (i = 0; i < PROPOSAL_MAX; i++) {
	92	proposal[i] = buffer_get_string(&b,NULL);
	93	debug2("kex_parse_kexinit: %s", proposal[i]);
	94	}
	95	/* first kex follows / reserved */
	96	i = buffer_get_char(&b);
	97	debug2("kex_parse_kexinit: first_kex_follows %d ", i);
	98	i = buffer_get_int(&b);
	99	debug2("kex_parse_kexinit: reserved %d ", i);
	100	buffer_free(&b);
	101	return proposal;
	102	}
	103
	104	static void
	105	kex_prop_free(char **proposal)
	106	{
	107	int i;
	108
	109	for (i = 0; i < PROPOSAL_MAX; i++)
	110	xfree(proposal[i]);
	111	xfree(proposal);
	112	}
	113
	114	static void
e9a17296	115	kex_protocol_error(int type, u_int32_t seq, void *ctxt)
3c0ef626	116	{
e9a17296	117	error("Hm, kex protocol error: type %d seq %u", type, seq);
3c0ef626	118	}
	119
	120	static void
e9a17296	121	kex_reset_dispatch(void)
3c0ef626	122	{
e9a17296	123	dispatch_range(SSH2_MSG_TRANSPORT_MIN,
	124	SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
	125	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
3c0ef626	126	}
	127
	128	void
	129	kex_finish(Kex *kex)
	130	{
e9a17296	131	kex_reset_dispatch();
3c0ef626	132
	133	packet_start(SSH2_MSG_NEWKEYS);
	134	packet_send();
	135	/* packet_write_wait(); */
	136	debug("SSH2_MSG_NEWKEYS sent");
	137
	138	debug("waiting for SSH2_MSG_NEWKEYS");
e9a17296	139	packet_read_expect(SSH2_MSG_NEWKEYS);
e9a17296	140	packet_check_eom();
3c0ef626	141	debug("SSH2_MSG_NEWKEYS received");
	142
	143	kex->done = 1;
	144	buffer_clear(&kex->peer);
	145	/* buffer_clear(&kex->my); */
	146	kex->flags &= ~KEX_INIT_SENT;
	147	xfree(kex->name);
	148	kex->name = NULL;
	149	}
	150
	151	void
	152	kex_send_kexinit(Kex *kex)
	153	{
700318f3	154	u_int32_t rand = 0;
	155	u_char *cookie;
	156	int i;
	157
3c0ef626	158	if (kex == NULL) {
	159	error("kex_send_kexinit: no kex, cannot rekey");
	160	return;
	161	}
	162	if (kex->flags & KEX_INIT_SENT) {
	163	debug("KEX_INIT_SENT");
	164	return;
	165	}
	166	kex->done = 0;
700318f3	167
	168	/* generate a random cookie */
	169	if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
	170	fatal("kex_send_kexinit: kex proposal too short");
	171	cookie = buffer_ptr(&kex->my);
	172	for (i = 0; i < KEX_COOKIE_LEN; i++) {
	173	if (i % 4 == 0)
	174	rand = arc4random();
	175	cookie[i] = rand;
	176	rand >>= 8;
	177	}
3c0ef626	178	packet_start(SSH2_MSG_KEXINIT);
	179	packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
	180	packet_send();
	181	debug("SSH2_MSG_KEXINIT sent");
	182	kex->flags \|= KEX_INIT_SENT;
	183	}
	184
	185	void
e9a17296	186	kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
3c0ef626	187	{
	188	char *ptr;
	189	int dlen;
	190	int i;
	191	Kex kex = (Kex )ctxt;
	192
	193	debug("SSH2_MSG_KEXINIT received");
	194	if (kex == NULL)
	195	fatal("kex_input_kexinit: no kex, cannot rekey");
	196
	197	ptr = packet_get_raw(&dlen);
	198	buffer_append(&kex->peer, ptr, dlen);
	199
	200	/* discard packet */
	201	for (i = 0; i < KEX_COOKIE_LEN; i++)
	202	packet_get_char();
	203	for (i = 0; i < PROPOSAL_MAX; i++)
	204	xfree(packet_get_string(NULL));
	205	packet_get_char();
	206	packet_get_int();
e9a17296	207	packet_check_eom();
3c0ef626	208
	209	kex_kexinit_finish(kex);
	210	}
	211
	212	Kex *
	213	kex_setup(char *proposal[PROPOSAL_MAX])
	214	{
	215	Kex *kex;
	216
	217	kex = xmalloc(sizeof(*kex));
	218	memset(kex, 0, sizeof(*kex));
	219	buffer_init(&kex->peer);
	220	buffer_init(&kex->my);
	221	kex_prop2buf(&kex->my, proposal);
	222	kex->done = 0;
	223
	224	kex_send_kexinit(kex); /* we start */
e9a17296	225	kex_reset_dispatch();
3c0ef626	226
	227	return kex;
	228	}
	229
	230	static void
	231	kex_kexinit_finish(Kex *kex)
	232	{
	233	if (!(kex->flags & KEX_INIT_SENT))
	234	kex_send_kexinit(kex);
	235
	236	kex_choose_conf(kex);
	237
e9a17296	238	switch (kex->kex_type) {
3c0ef626	239	case DH_GRP1_SHA1:
	240	kexdh(kex);
	241	break;
	242	case DH_GEX_SHA1:
	243	kexgex(kex);
	244	break;
	245	default:
	246	fatal("Unsupported key exchange %d", kex->kex_type);
	247	}
	248	}
	249
	250	static void
	251	choose_enc(Enc enc, char client, char *server)
	252	{
	253	char *name = match_list(client, server, NULL);
	254	if (name == NULL)
	255	fatal("no matching cipher found: client %s server %s", client, server);
e9a17296	256	if ((enc->cipher = cipher_by_name(name)) == NULL)
3c0ef626	257	fatal("matching cipher is not supported: %s", name);
	258	enc->name = name;
	259	enc->enabled = 0;
	260	enc->iv = NULL;
	261	enc->key = NULL;
e9a17296	262	enc->key_len = cipher_keylen(enc->cipher);
e9a17296	263	enc->block_size = cipher_blocksize(enc->cipher);
3c0ef626	264	}
	265	static void
	266	choose_mac(Mac mac, char client, char *server)
	267	{
	268	char *name = match_list(client, server, NULL);
	269	if (name == NULL)
	270	fatal("no matching mac found: client %s server %s", client, server);
	271	if (mac_init(mac, name) < 0)
	272	fatal("unsupported mac %s", name);
	273	/* truncate the key */
	274	if (datafellows & SSH_BUG_HMAC)
	275	mac->key_len = 16;
	276	mac->name = name;
	277	mac->key = NULL;
	278	mac->enabled = 0;
	279	}
	280	static void
	281	choose_comp(Comp comp, char client, char *server)
	282	{
	283	char *name = match_list(client, server, NULL);
	284	if (name == NULL)
	285	fatal("no matching comp found: client %s server %s", client, server);
	286	if (strcmp(name, "zlib") == 0) {
	287	comp->type = 1;
	288	} else if (strcmp(name, "none") == 0) {
	289	comp->type = 0;
	290	} else {
	291	fatal("unsupported comp %s", name);
	292	}
	293	comp->name = name;
	294	}
	295	static void
	296	choose_kex(Kex k, char client, char *server)
	297	{
	298	k->name = match_list(client, server, NULL);
	299	if (k->name == NULL)
	300	fatal("no kex alg");
	301	if (strcmp(k->name, KEX_DH1) == 0) {
	302	k->kex_type = DH_GRP1_SHA1;
	303	} else if (strcmp(k->name, KEX_DHGEX) == 0) {
	304	k->kex_type = DH_GEX_SHA1;
	305	} else
	306	fatal("bad kex alg %s", k->name);
	307	}
	308	static void
	309	choose_hostkeyalg(Kex k, char client, char *server)
	310	{
	311	char *hostkeyalg = match_list(client, server, NULL);
	312	if (hostkeyalg == NULL)
	313	fatal("no hostkey alg");
	314	k->hostkey_type = key_type_from_name(hostkeyalg);
	315	if (k->hostkey_type == KEY_UNSPEC)
	316	fatal("bad hostkey alg '%s'", hostkeyalg);
	317	xfree(hostkeyalg);
	318	}
	319
	320	static void
	321	kex_choose_conf(Kex *kex)
	322	{
	323	Newkeys *newkeys;
	324	char my, peer;
	325	char cprop, sprop;
	326	int nenc, nmac, ncomp;
	327	int mode;
328	int ctos; /* direction: if true client-to-server */
329	int need;
330
331	my = kex_buf2prop(&kex->my);
332	peer = kex_buf2prop(&kex->peer);
333
334	if (kex->server) {
335	cprop=peer;
336	sprop=my;
337	} else {
338	cprop=my;
339	sprop=peer;
340	}
341
342	/* Algorithm Negotiation */
343	for (mode = 0; mode < MODE_MAX; mode++) {
344	newkeys = xmalloc(sizeof(*newkeys));
345	memset(newkeys, 0, sizeof(*newkeys));
346	kex->newkeys[mode] = newkeys;
347	ctos = (!kex->server && mode == MODE_OUT) \|\| (kex->server && mode == MODE_IN);
348	nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
349	nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
350	ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
351	choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]);
352	choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]);
353	choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
354	debug("kex: %s %s %s %s",
355	ctos ? "client->server" : "server->client",
356	newkeys->enc.name,
357	newkeys->mac.name,
358	newkeys->comp.name);
359	}
360	choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
361	choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
362	sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
363	need = 0;
364	for (mode = 0; mode < MODE_MAX; mode++) {
365	newkeys = kex->newkeys[mode];
e9a17296	366	if (need < newkeys->enc.key_len)
	367	need = newkeys->enc.key_len;
	368	if (need < newkeys->enc.block_size)
	369	need = newkeys->enc.block_size;
3c0ef626	370	if (need < newkeys->mac.key_len)
	371	need = newkeys->mac.key_len;
	372	}
	373	/* XXX need runden? */
	374	kex->we_need = need;
	375
	376	kex_prop_free(my);
	377	kex_prop_free(peer);
	378	}
	379
	380	static u_char *
	381	derive_key(Kex kex, int id, int need, u_char hash, BIGNUM *shared_secret)
	382	{
	383	Buffer b;
e9a17296	384	const EVP_MD *evp_md = EVP_sha1();
3c0ef626	385	EVP_MD_CTX md;
	386	char c = id;
	387	int have;
e9a17296	388	int mdsz = EVP_MD_size(evp_md);
3c0ef626	389	u_char *digest = xmalloc(roundup(need, mdsz));
	390
	391	buffer_init(&b);
	392	buffer_put_bignum2(&b, shared_secret);
	393
	394	/* K1 = HASH(K \|\| H \|\| "A" \|\| session_id) */
	395	EVP_DigestInit(&md, evp_md);
	396	if (!(datafellows & SSH_BUG_DERIVEKEY))
	397	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	398	EVP_DigestUpdate(&md, hash, mdsz);
	399	EVP_DigestUpdate(&md, &c, 1);
	400	EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
	401	EVP_DigestFinal(&md, digest, NULL);
	402
	403	/*
	404	* expand key:
	405	* Kn = HASH(K \|\| H \|\| K1 \|\| K2 \|\| ... \|\| Kn-1)
	406	* Key = K1 \|\| K2 \|\| ... \|\| Kn
	407	*/
	408	for (have = mdsz; need > have; have += mdsz) {
	409	EVP_DigestInit(&md, evp_md);
	410	if (!(datafellows & SSH_BUG_DERIVEKEY))
	411	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	412	EVP_DigestUpdate(&md, hash, mdsz);
	413	EVP_DigestUpdate(&md, digest, have);
	414	EVP_DigestFinal(&md, digest + have, NULL);
	415	}
	416	buffer_free(&b);
	417	#ifdef DEBUG_KEX
	418	fprintf(stderr, "key '%c'== ", c);
	419	dump_digest("key", digest, need);
	420	#endif
	421	return digest;
	422	}
	423
	424	Newkeys *current_keys[MODE_MAX];
	425
	426	#define NKEYS 6
	427	void
	428	kex_derive_keys(Kex kex, u_char hash, BIGNUM *shared_secret)
	429	{
	430	u_char *keys[NKEYS];
	431	int i, mode, ctos;
	432
	433	for (i = 0; i < NKEYS; i++)
	434	keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
	435
	436	debug("kex_derive_keys");
	437	for (mode = 0; mode < MODE_MAX; mode++) {
	438	current_keys[mode] = kex->newkeys[mode];
	439	kex->newkeys[mode] = NULL;
	440	ctos = (!kex->server && mode == MODE_OUT) \|\| (kex->server && mode == MODE_IN);
	441	current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
	442	current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
	443	current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
	444	}
	445	}
	446
	447	Newkeys *
	448	kex_get_newkeys(int mode)
	449	{
	450	Newkeys *ret;
	451
	452	ret = current_keys[mode];
453	current_keys[mode] = NULL;
454	return ret;
455	}
456
457	#if defined(DEBUG_KEX) \|\| defined(DEBUG_KEXDH)
458	void
459	dump_digest(char msg, u_char digest, int len)
460	{
461	int i;
462
463	fprintf(stderr, "%s\n", msg);
e9a17296	464	for (i = 0; i< len; i++) {
3c0ef626	465	fprintf(stderr, "%02x", digest[i]);
	466	if (i%32 == 31)
	467	fprintf(stderr, "\n");
	468	else if (i%8 == 7)
	469	fprintf(stderr, " ");
	470	}
	471	fprintf(stderr, "\n");
	472	}
	473	#endif