[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 1.27 2001/04/03 23:32:11 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_send_newkeys(void)
{
	packet_start(SSH2_MSG_NEWKEYS);
	packet_send();
	/* packet_write_wait(); */
	debug("SSH2_MSG_NEWKEYS sent");
}

void
kex_input_newkeys(int type, int plen, void *ctxt)
{
	Kex *kex = ctxt;
	int i;

	debug("SSH2_MSG_NEWKEYS received");
	kex->newkeys = 1;
	for (i = 30; i <= 49; i++)
		dispatch_set(i, &kex_protocol_error);
	buffer_clear(&kex->peer);
	/* buffer_clear(&kex->my); */
	kex->flags &= ~KEX_INIT_SENT;
}

void
kex_send_kexinit(Kex *kex)
{
	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");

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

	kex_kexinit_finish(kex);
}

Kex *
kex_start(char *proposal[PROPOSAL_MAX])
{
	Kex *kex;
	int i;

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

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

	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
	dispatch_set(SSH2_MSG_NEWKEYS, &kex_input_newkeys);
	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;
	}

	for (mode = 0; mode < MODE_MAX; mode++) {
		newkeys = xmalloc(sizeof(*newkeys));
		memset(newkeys, 0, sizeof(*newkeys));
		kex->keys[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->keys[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(((need+mdsz-1)/mdsz)*mdsz);

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

	EVP_DigestInit(&md, evp_md);
	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));	/* shared_secret K */
	EVP_DigestUpdate(&md, hash, mdsz);		/* transport-06 */
	EVP_DigestUpdate(&md, &c, 1);			/* key id */
	EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
	EVP_DigestFinal(&md, digest, NULL);

	/* expand */
	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 *x_newkeys[MODE_MAX];

#define NKEYS	6
void
kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
{
	Newkeys *newkeys;
	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++) {
		newkeys = kex->keys[mode];
		ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
		newkeys->enc.iv  = keys[ctos ? 0 : 1];
		newkeys->enc.key = keys[ctos ? 2 : 3];
		newkeys->mac.key = keys[ctos ? 4 : 5];
		x_newkeys[mode] = newkeys;
	}
}

Newkeys *
kex_get_newkeys(int mode)
{
	return x_newkeys[mode];
}

#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"
d1ac6175	26	RCSID("$OpenBSD: kex.c,v 1.27 2001/04/03 23:32:11 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
a5c9ffdb	114	void
	115	kex_send_newkeys(void)
	116	{
	117	packet_start(SSH2_MSG_NEWKEYS);
	118	packet_send();
	119	/* packet_write_wait(); */
	120	debug("SSH2_MSG_NEWKEYS sent");
	121	}
4f8c6159	122
a5c9ffdb	123	void
	124	kex_input_newkeys(int type, int plen, void *ctxt)
	125	{
	126	Kex *kex = ctxt;
	127	int i;
4f8c6159	128
a5c9ffdb	129	debug("SSH2_MSG_NEWKEYS received");
	130	kex->newkeys = 1;
	131	for (i = 30; i <= 49; i++)
	132	dispatch_set(i, &kex_protocol_error);
	133	buffer_clear(&kex->peer);
d1ac6175	134	/* buffer_clear(&kex->my); */
a5c9ffdb	135	kex->flags &= ~KEX_INIT_SENT;
4f8c6159	136	}
4f8c6159	137
a5c9ffdb	138	void
a5c9ffdb	139	kex_send_kexinit(Kex *kex)
94ec8c6b	140	{
a5c9ffdb	141	packet_start(SSH2_MSG_KEXINIT);
	142	packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
	143	packet_send();
	144	debug("SSH2_MSG_KEXINIT sent");
	145	kex->flags \|= KEX_INIT_SENT;
	146	}
2b87da3b	147
a5c9ffdb	148	void
	149	kex_input_kexinit(int type, int plen, void *ctxt)
	150	{
	151	char *ptr;
	152	int dlen;
	153	Kex kex = (Kex )ctxt;
94ec8c6b	154
a5c9ffdb	155	debug("SSH2_MSG_KEXINIT received");
94ec8c6b	156
a5c9ffdb	157	ptr = packet_get_raw(&dlen);
a5c9ffdb	158	buffer_append(&kex->peer, ptr, dlen);
94ec8c6b	159
a5c9ffdb	160	kex_kexinit_finish(kex);
94ec8c6b	161	}
94ec8c6b	162
a5c9ffdb	163	Kex *
a5c9ffdb	164	kex_start(char *proposal[PROPOSAL_MAX])
4f8c6159	165	{
a5c9ffdb	166	Kex *kex;
a5c9ffdb	167	int i;
4f8c6159	168
a5c9ffdb	169	kex = xmalloc(sizeof(*kex));
	170	memset(kex, 0, sizeof(*kex));
	171	buffer_init(&kex->peer);
	172	buffer_init(&kex->my);
	173	kex_prop2buf(&kex->my, proposal);
	174	kex->newkeys = 0;
	175
	176	kex_send_kexinit(kex); /* we start */
	177	/* Numbers 30-49 are used for kex packets */
	178	for (i = 30; i <= 49; i++)
	179	dispatch_set(i, kex_protocol_error);
	180
	181	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
	182	dispatch_set(SSH2_MSG_NEWKEYS, &kex_input_newkeys);
	183	return kex;
	184	}
4f8c6159	185
a5c9ffdb	186	void
	187	kex_kexinit_finish(Kex *kex)
	188	{
	189	if (!(kex->flags & KEX_INIT_SENT))
	190	kex_send_kexinit(kex);
	191
	192	kex_choose_conf(kex);
	193
	194	switch(kex->kex_type) {
	195	case DH_GRP1_SHA1:
	196	kexdh(kex);
	197	break;
	198	case DH_GEX_SHA1:
	199	kexgex(kex);
	200	break;
	201	default:
	202	fatal("Unsupported key exchange %d", kex->kex_type);
4f8c6159	203	}
4f8c6159	204	}
4f8c6159	205
4f8c6159	206	void
	207	choose_enc(Enc enc, char client, char *server)
	208	{
cab80f75	209	char *name = match_list(client, server, NULL);
4f8c6159	210	if (name == NULL)
4f8c6159	211	fatal("no matching cipher found: client %s server %s", client, server);
94ec8c6b	212	enc->cipher = cipher_by_name(name);
	213	if (enc->cipher == NULL)
	214	fatal("matching cipher is not supported: %s", name);
4f8c6159	215	enc->name = name;
	216	enc->enabled = 0;
	217	enc->iv = NULL;
	218	enc->key = NULL;
	219	}
	220	void
	221	choose_mac(Mac mac, char client, char *server)
	222	{
cab80f75	223	char *name = match_list(client, server, NULL);
4f8c6159	224	if (name == NULL)
4f8c6159	225	fatal("no matching mac found: client %s server %s", client, server);
b2552997	226	if (mac_init(mac, name) < 0)
4f8c6159	227	fatal("unsupported mac %s", name);
b2552997	228	/* truncate the key */
	229	if (datafellows & SSH_BUG_HMAC)
	230	mac->key_len = 16;
4f8c6159	231	mac->name = name;
4f8c6159	232	mac->key = NULL;
	233	mac->enabled = 0;
	234	}
	235	void
	236	choose_comp(Comp comp, char client, char *server)
	237	{
cab80f75	238	char *name = match_list(client, server, NULL);
4f8c6159	239	if (name == NULL)
	240	fatal("no matching comp found: client %s server %s", client, server);
	241	if (strcmp(name, "zlib") == 0) {
	242	comp->type = 1;
	243	} else if (strcmp(name, "none") == 0) {
	244	comp->type = 0;
	245	} else {
	246	fatal("unsupported comp %s", name);
	247	}
	248	comp->name = name;
	249	}
	250	void
	251	choose_kex(Kex k, char client, char *server)
	252	{
cab80f75	253	k->name = match_list(client, server, NULL);
4f8c6159	254	if (k->name == NULL)
4f8c6159	255	fatal("no kex alg");
94ec8c6b	256	if (strcmp(k->name, KEX_DH1) == 0) {
	257	k->kex_type = DH_GRP1_SHA1;
	258	} else if (strcmp(k->name, KEX_DHGEX) == 0) {
	259	k->kex_type = DH_GEX_SHA1;
	260	} else
4f8c6159	261	fatal("bad kex alg %s", k->name);
	262	}
	263	void
	264	choose_hostkeyalg(Kex k, char client, char *server)
	265	{
cab80f75	266	char *hostkeyalg = match_list(client, server, NULL);
fa08c86b	267	if (hostkeyalg == NULL)
4f8c6159	268	fatal("no hostkey alg");
fa08c86b	269	k->hostkey_type = key_type_from_name(hostkeyalg);
	270	if (k->hostkey_type == KEY_UNSPEC)
	271	fatal("bad hostkey alg '%s'", hostkeyalg);
eea39c02	272	xfree(hostkeyalg);
4f8c6159	273	}
4f8c6159	274
a5c9ffdb	275	void
d1ac6175	276	kex_choose_conf(Kex *kex)
4f8c6159	277	{
d1ac6175	278	Newkeys *newkeys;
a5c9ffdb	279	char my, peer;
a5c9ffdb	280	char cprop, sprop;
d1ac6175	281	int nenc, nmac, ncomp;
4f8c6159	282	int mode;
	283	int ctos; /* direction: if true client-to-server */
	284	int need;
4f8c6159	285
d1ac6175	286	my = kex_buf2prop(&kex->my);
d1ac6175	287	peer = kex_buf2prop(&kex->peer);
a5c9ffdb	288
d1ac6175	289	if (kex->server) {
a5c9ffdb	290	cprop=peer;
	291	sprop=my;
	292	} else {
	293	cprop=my;
	294	sprop=peer;
	295	}
4f8c6159	296
4f8c6159	297	for (mode = 0; mode < MODE_MAX; mode++) {
d1ac6175	298	newkeys = xmalloc(sizeof(*newkeys));
	299	memset(newkeys, 0, sizeof(*newkeys));
	300	kex->keys[mode] = newkeys;
	301	ctos = (!kex->server && mode == MODE_OUT) \|\| (kex->server && mode == MODE_IN);
4f8c6159	302	nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
	303	nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
	304	ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
d1ac6175	305	choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]);
	306	choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]);
	307	choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
4f8c6159	308	debug("kex: %s %s %s %s",
4f8c6159	309	ctos ? "client->server" : "server->client",
d1ac6175	310	newkeys->enc.name,
	311	newkeys->mac.name,
	312	newkeys->comp.name);
4f8c6159	313	}
d1ac6175	314	choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
d1ac6175	315	choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
4f8c6159	316	sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
4f8c6159	317	need = 0;
4f8c6159	318	for (mode = 0; mode < MODE_MAX; mode++) {
d1ac6175	319	newkeys = kex->keys[mode];
	320	if (need < newkeys->enc.cipher->key_len)
	321	need = newkeys->enc.cipher->key_len;
	322	if (need < newkeys->enc.cipher->block_size)
	323	need = newkeys->enc.cipher->block_size;
	324	if (need < newkeys->mac.key_len)
	325	need = newkeys->mac.key_len;
4f8c6159	326	}
71276795	327	/* XXX need runden? */
d1ac6175	328	kex->we_need = need;
a5c9ffdb	329
	330	kex_prop_free(my);
	331	kex_prop_free(peer);
a5c9ffdb	332	}
	333
	334	u_char *
d1ac6175	335	derive_key(Kex kex, int id, int need, u_char hash, BIGNUM *shared_secret)
a5c9ffdb	336	{
	337	Buffer b;
	338	EVP_MD *evp_md = EVP_sha1();
	339	EVP_MD_CTX md;
	340	char c = id;
	341	int have;
	342	int mdsz = evp_md->md_size;
	343	u_char digest = xmalloc(((need+mdsz-1)/mdsz)mdsz);
	344
	345	buffer_init(&b);
	346	buffer_put_bignum2(&b, shared_secret);
	347
	348	EVP_DigestInit(&md, evp_md);
	349	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); /* shared_secret K */
	350	EVP_DigestUpdate(&md, hash, mdsz); /* transport-06 */
	351	EVP_DigestUpdate(&md, &c, 1); /* key id */
d1ac6175	352	EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
a5c9ffdb	353	EVP_DigestFinal(&md, digest, NULL);
	354
	355	/* expand */
	356	for (have = mdsz; need > have; have += mdsz) {
	357	EVP_DigestInit(&md, evp_md);
	358	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
	359	EVP_DigestUpdate(&md, hash, mdsz);
	360	EVP_DigestUpdate(&md, digest, have);
	361	EVP_DigestFinal(&md, digest + have, NULL);
	362	}
	363	buffer_free(&b);
	364	#ifdef DEBUG_KEX
	365	fprintf(stderr, "key '%c'== ", c);
	366	dump_digest("key", digest, need);
	367	#endif
	368	return digest;
4f8c6159	369	}
4f8c6159	370
d1ac6175	371	Newkeys *x_newkeys[MODE_MAX];
d1ac6175	372
cab80f75	373	#define NKEYS 6
a5c9ffdb	374	void
d1ac6175	375	kex_derive_keys(Kex kex, u_char hash, BIGNUM *shared_secret)
4f8c6159	376	{
d1ac6175	377	Newkeys *newkeys;
1e3b8b07	378	u_char *keys[NKEYS];
d1ac6175	379	int i, mode, ctos;
4f8c6159	380
4f8c6159	381	for (i = 0; i < NKEYS; i++)
d1ac6175	382	keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
4f8c6159	383
d1ac6175	384	debug("kex_derive_keys");
4f8c6159	385	for (mode = 0; mode < MODE_MAX; mode++) {
d1ac6175	386	newkeys = kex->keys[mode];
	387	ctos = (!kex->server && mode == MODE_OUT) \|\| (kex->server && mode == MODE_IN);
	388	newkeys->enc.iv = keys[ctos ? 0 : 1];
	389	newkeys->enc.key = keys[ctos ? 2 : 3];
	390	newkeys->mac.key = keys[ctos ? 4 : 5];
	391	x_newkeys[mode] = newkeys;
4f8c6159	392	}
4f8c6159	393	}
a5c9ffdb	394
d1ac6175	395	Newkeys *
	396	kex_get_newkeys(int mode)
	397	{
	398	return x_newkeys[mode];
	399	}
	400
a5c9ffdb	401	#if defined(DEBUG_KEX) \|\| defined(DEBUG_KEXDH)
	402	void
	403	dump_digest(char msg, u_char digest, int len)
	404	{
	405	int i;
	406
	407	fprintf(stderr, "%s\n", msg);
	408	for (i = 0; i< len; i++){
	409	fprintf(stderr, "%02x", digest[i]);
	410	if (i%32 == 31)
	411	fprintf(stderr, "\n");
	412	else if (i%8 == 7)
	413	fprintf(stderr, " ");
	414	}
	415	fprintf(stderr, "\n");
	416	}
	417	#endif