[thirdparty/openssh-portable.git] / kexecdh.c

/* $OpenBSD: kexecdh.c,v 1.10 2019/01/21 10:40:11 djm Exp $ */
/*
 * Copyright (c) 2010 Damien Miller.  All rights reserved.
 * Copyright (c) 2019 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"

#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)

#include <sys/types.h>

#include <stdio.h>
#include <string.h>
#include <signal.h>

#include <openssl/ecdh.h>

#include "sshkey.h"
#include "kex.h"
#include "sshbuf.h"
#include "digest.h"
#include "ssherr.h"

static int
kex_ecdh_dec_key_group(struct kex *, const struct sshbuf *, EC_KEY *key,
    const EC_GROUP *, struct sshbuf **);

int
kex_ecdh_keypair(struct kex *kex)
{
	EC_KEY *client_key = NULL;
	const EC_GROUP *group;
	const EC_POINT *public_key;
	struct sshbuf *buf = NULL;
	int r;

	if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
		r = SSH_ERR_ALLOC_FAIL;
		goto out;
	}
	if (EC_KEY_generate_key(client_key) != 1) {
		r = SSH_ERR_LIBCRYPTO_ERROR;
		goto out;
	}
	group = EC_KEY_get0_group(client_key);
	public_key = EC_KEY_get0_public_key(client_key);

	if ((buf = sshbuf_new()) == NULL) {
		r = SSH_ERR_ALLOC_FAIL;
		goto out;
	}
	if ((r = sshbuf_put_ec(buf, public_key, group)) != 0 ||
	    (r = sshbuf_get_u32(buf, NULL)) != 0)
		goto out;
#ifdef DEBUG_KEXECDH
	fputs("client private key:\n", stderr);
	sshkey_dump_ec_key(client_key);
#endif
	kex->ec_client_key = client_key;
	kex->ec_group = group;
	client_key = NULL;	/* owned by the kex */
	kex->client_pub = buf;
	buf = NULL;
 out:
	EC_KEY_free(client_key);
	sshbuf_free(buf);
	return r;
}

int
kex_ecdh_enc(struct kex *kex, const struct sshbuf *client_blob,
    struct sshbuf **server_blobp, struct sshbuf **shared_secretp)
{
	const EC_GROUP *group;
	const EC_POINT *pub_key;
	EC_KEY *server_key = NULL;
	struct sshbuf *server_blob = NULL;
	int r;

	*server_blobp = NULL;
	*shared_secretp = NULL;

	if ((server_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
		r = SSH_ERR_ALLOC_FAIL;
		goto out;
	}
	if (EC_KEY_generate_key(server_key) != 1) {
		r = SSH_ERR_LIBCRYPTO_ERROR;
		goto out;
	}
	group = EC_KEY_get0_group(server_key);

#ifdef DEBUG_KEXECDH
	fputs("server private key:\n", stderr);
	sshkey_dump_ec_key(server_key);
#endif
	pub_key = EC_KEY_get0_public_key(server_key);
	if ((server_blob = sshbuf_new()) == NULL) {
		r = SSH_ERR_ALLOC_FAIL;
		goto out;
	}
	if ((r = sshbuf_put_ec(server_blob, pub_key, group)) != 0 ||
	    (r = sshbuf_get_u32(server_blob, NULL)) != 0)
		goto out;
	if ((r = kex_ecdh_dec_key_group(kex, client_blob, server_key, group,
	    shared_secretp)) != 0)
		goto out;
	*server_blobp = server_blob;
	server_blob = NULL;
 out:
	EC_KEY_free(server_key);
	sshbuf_free(server_blob);
	return r;
}

static int
kex_ecdh_dec_key_group(struct kex *kex, const struct sshbuf *ec_blob,
    EC_KEY *key, const EC_GROUP *group, struct sshbuf **shared_secretp)
{
	struct sshbuf *buf = NULL;
	BIGNUM *shared_secret = NULL;
	EC_POINT *dh_pub = NULL;
	u_char *kbuf = NULL;
	size_t klen = 0;
	int r;

	*shared_secretp = NULL;

	if ((buf = sshbuf_new()) == NULL) {
		r = SSH_ERR_ALLOC_FAIL;
		goto out;
	}
	if ((r = sshbuf_put_stringb(buf, ec_blob)) != 0)
		goto out;
	if ((dh_pub = EC_POINT_new(group)) == NULL) {
		r = SSH_ERR_ALLOC_FAIL;
		goto out;
	}
	if ((r = sshbuf_get_ec(buf, dh_pub, group)) != 0) {
		goto out;
	}
	sshbuf_reset(buf);

#ifdef DEBUG_KEXECDH
	fputs("public key:\n", stderr);
	sshkey_dump_ec_point(group, dh_pub);
#endif
	if (sshkey_ec_validate_public(group, dh_pub) != 0) {
		r = SSH_ERR_MESSAGE_INCOMPLETE;
		goto out;
	}
	klen = (EC_GROUP_get_degree(group) + 7) / 8;
	if ((kbuf = malloc(klen)) == NULL ||
	    (shared_secret = BN_new()) == NULL) {
		r = SSH_ERR_ALLOC_FAIL;
		goto out;
	}
	if (ECDH_compute_key(kbuf, klen, dh_pub, key, NULL) != (int)klen ||
	    BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
		r = SSH_ERR_LIBCRYPTO_ERROR;
		goto out;
	}
#ifdef DEBUG_KEXECDH
	dump_digest("shared secret", kbuf, klen);
#endif
	if ((r = sshbuf_put_bignum2(buf, shared_secret)) != 0)
		goto out;
	*shared_secretp = buf;
	buf = NULL;
 out:
	EC_POINT_clear_free(dh_pub);
	BN_clear_free(shared_secret);
	freezero(kbuf, klen);
	sshbuf_free(buf);
	return r;
}

int
kex_ecdh_dec(struct kex *kex, const struct sshbuf *server_blob,
    struct sshbuf **shared_secretp)
{
	int r;

	r = kex_ecdh_dec_key_group(kex, server_blob, kex->ec_client_key,
	    kex->ec_group, shared_secretp);
	EC_KEY_free(kex->ec_client_key);
	kex->ec_client_key = NULL;
	return r;
}

#else

#include "ssherr.h"

struct kex;
struct sshbuf;
struct sshkey;

int
kex_ecdh_keypair(struct kex *kex)
{
	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
}

int
kex_ecdh_enc(struct kex *kex, const struct sshbuf *client_blob,
    struct sshbuf **server_blobp, struct sshbuf **shared_secretp)
{
	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
}

int
kex_ecdh_dec(struct kex *kex, const struct sshbuf *server_blob,
    struct sshbuf **shared_secretp)
{
	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
}
#endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */
Commit	Line	Data
aaca72d6	1	/* $OpenBSD: kexecdh.c,v 1.10 2019/01/21 10:40:11 djm Exp $ */
eb8b60e3	2	/*
eb8b60e3	3	* Copyright (c) 2010 Damien Miller. All rights reserved.
92dda34e	4	* Copyright (c) 2019 Markus Friedl. All rights reserved.
eb8b60e3 DM	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions
	8	* are met:
	9	* 1. Redistributions of source code must retain the above copyright
	10	* notice, this list of conditions and the following disclaimer.
	11	* 2. Redistributions in binary form must reproduce the above copyright
	12	* notice, this list of conditions and the following disclaimer in the
	13	* documentation and/or other materials provided with the distribution.
	14	*
	15	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	16	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	17	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	18	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	19	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	20	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	21	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	22	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	23	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	24	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	25	*/
	26
c79ff077 DM	27	#include "includes.h"
c79ff077 DM	28
72ef7c14	29	#if defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC)
6af914a1	30
eb8b60e3 DM	31	#include <sys/types.h>
eb8b60e3 DM	32
92dda34e	33	#include <stdio.h>
eb8b60e3	34	#include <string.h>
92dda34e	35	#include <signal.h>
eb8b60e3	36
eb8b60e3 DM	37	#include <openssl/ecdh.h>
eb8b60e3 DM	38
57d10cbe	39	#include "sshkey.h"
eb8b60e3	40	#include "kex.h"
57d10cbe	41	#include "sshbuf.h"
b3051d01	42	#include "digest.h"
57d10cbe	43	#include "ssherr.h"
eb8b60e3	44
92dda34e	45	static int
71e67fff	46	kex_ecdh_dec_key_group(struct kex , const struct sshbuf , EC_KEY *key,
92dda34e	47	const EC_GROUP , struct sshbuf *);
92dda34e	48
57d10cbe	49	int
92dda34e	50	kex_ecdh_keypair(struct kex *kex)
	51	{
	52	EC_KEY *client_key = NULL;
	53	const EC_GROUP *group;
	54	const EC_POINT *public_key;
	55	struct sshbuf *buf = NULL;
	56	int r;
	57
	58	if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
	59	r = SSH_ERR_ALLOC_FAIL;
	60	goto out;
	61	}
	62	if (EC_KEY_generate_key(client_key) != 1) {
	63	r = SSH_ERR_LIBCRYPTO_ERROR;
	64	goto out;
	65	}
	66	group = EC_KEY_get0_group(client_key);
	67	public_key = EC_KEY_get0_public_key(client_key);
	68
	69	if ((buf = sshbuf_new()) == NULL) {
	70	r = SSH_ERR_ALLOC_FAIL;
	71	goto out;
	72	}
	73	if ((r = sshbuf_put_ec(buf, public_key, group)) != 0 \|\|
	74	(r = sshbuf_get_u32(buf, NULL)) != 0)
	75	goto out;
	76	#ifdef DEBUG_KEXECDH
	77	fputs("client private key:\n", stderr);
	78	sshkey_dump_ec_key(client_key);
	79	#endif
	80	kex->ec_client_key = client_key;
	81	kex->ec_group = group;
	82	client_key = NULL; /* owned by the kex */
aaca72d6	83	kex->client_pub = buf;
92dda34e	84	buf = NULL;
	85	out:
	86	EC_KEY_free(client_key);
	87	sshbuf_free(buf);
	88	return r;
	89	}
	90
	91	int
71e67fff	92	kex_ecdh_enc(struct kex kex, const struct sshbuf client_blob,
92dda34e	93	struct sshbuf server_blobp, struct sshbuf shared_secretp)
	94	{
	95	const EC_GROUP *group;
	96	const EC_POINT *pub_key;
	97	EC_KEY *server_key = NULL;
	98	struct sshbuf *server_blob = NULL;
	99	int r;
	100
	101	*server_blobp = NULL;
	102	*shared_secretp = NULL;
	103
	104	if ((server_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL) {
	105	r = SSH_ERR_ALLOC_FAIL;
	106	goto out;
	107	}
	108	if (EC_KEY_generate_key(server_key) != 1) {
	109	r = SSH_ERR_LIBCRYPTO_ERROR;
	110	goto out;
	111	}
	112	group = EC_KEY_get0_group(server_key);
	113
	114	#ifdef DEBUG_KEXECDH
	115	fputs("server private key:\n", stderr);
	116	sshkey_dump_ec_key(server_key);
	117	#endif
	118	pub_key = EC_KEY_get0_public_key(server_key);
	119	if ((server_blob = sshbuf_new()) == NULL) {
	120	r = SSH_ERR_ALLOC_FAIL;
	121	goto out;
	122	}
	123	if ((r = sshbuf_put_ec(server_blob, pub_key, group)) != 0 \|\|
	124	(r = sshbuf_get_u32(server_blob, NULL)) != 0)
	125	goto out;
71e67fff	126	if ((r = kex_ecdh_dec_key_group(kex, client_blob, server_key, group,
92dda34e	127	shared_secretp)) != 0)
	128	goto out;
	129	*server_blobp = server_blob;
	130	server_blob = NULL;
	131	out:
	132	EC_KEY_free(server_key);
	133	sshbuf_free(server_blob);
	134	return r;
	135	}
	136
	137	static int
71e67fff	138	kex_ecdh_dec_key_group(struct kex kex, const struct sshbuf ec_blob,
92dda34e	139	EC_KEY key, const EC_GROUP group, struct sshbuf **shared_secretp)
eb8b60e3	140	{
92dda34e	141	struct sshbuf *buf = NULL;
	142	BIGNUM *shared_secret = NULL;
	143	EC_POINT *dh_pub = NULL;
	144	u_char *kbuf = NULL;
	145	size_t klen = 0;
57d10cbe	146	int r;
eb8b60e3	147
92dda34e	148	*shared_secretp = NULL;
	149
	150	if ((buf = sshbuf_new()) == NULL) {
	151	r = SSH_ERR_ALLOC_FAIL;
	152	goto out;
	153	}
71e67fff	154	if ((r = sshbuf_put_stringb(buf, ec_blob)) != 0)
92dda34e	155	goto out;
92dda34e	156	if ((dh_pub = EC_POINT_new(group)) == NULL) {
	157	r = SSH_ERR_ALLOC_FAIL;
	158	goto out;
	159	}
	160	if ((r = sshbuf_get_ec(buf, dh_pub, group)) != 0) {
	161	goto out;
57d10cbe	162	}
92dda34e	163	sshbuf_reset(buf);
	164
	165	#ifdef DEBUG_KEXECDH
	166	fputs("public key:\n", stderr);
	167	sshkey_dump_ec_point(group, dh_pub);
eb8b60e3	168	#endif
92dda34e	169	if (sshkey_ec_validate_public(group, dh_pub) != 0) {
	170	r = SSH_ERR_MESSAGE_INCOMPLETE;
	171	goto out;
	172	}
	173	klen = (EC_GROUP_get_degree(group) + 7) / 8;
	174	if ((kbuf = malloc(klen)) == NULL \|\|
	175	(shared_secret = BN_new()) == NULL) {
	176	r = SSH_ERR_ALLOC_FAIL;
	177	goto out;
	178	}
	179	if (ECDH_compute_key(kbuf, klen, dh_pub, key, NULL) != (int)klen \|\|
	180	BN_bin2bn(kbuf, klen, shared_secret) == NULL) {
	181	r = SSH_ERR_LIBCRYPTO_ERROR;
	182	goto out;
57d10cbe	183	}
92dda34e	184	#ifdef DEBUG_KEXECDH
92dda34e	185	dump_digest("shared secret", kbuf, klen);
eb8b60e3	186	#endif
92dda34e	187	if ((r = sshbuf_put_bignum2(buf, shared_secret)) != 0)
	188	goto out;
	189	*shared_secretp = buf;
	190	buf = NULL;
	191	out:
	192	EC_POINT_clear_free(dh_pub);
	193	BN_clear_free(shared_secret);
	194	freezero(kbuf, klen);
	195	sshbuf_free(buf);
	196	return r;
	197	}
	198
	199	int
71e67fff	200	kex_ecdh_dec(struct kex kex, const struct sshbuf server_blob,
92dda34e	201	struct sshbuf **shared_secretp)
	202	{
	203	int r;
	204
71e67fff	205	r = kex_ecdh_dec_key_group(kex, server_blob, kex->ec_client_key,
92dda34e	206	kex->ec_group, shared_secretp);
	207	EC_KEY_free(kex->ec_client_key);
	208	kex->ec_client_key = NULL;
	209	return r;
eb8b60e3	210	}
97370f6c DT	211
	212	#else
	213
fa5bd810 DT	214	#include "ssherr.h"
fa5bd810 DT	215
edd1d3a6 DM	216	struct kex;
	217	struct sshbuf;
	218	struct sshkey;
97370f6c DT	219
	220	int
	221	kex_ecdh_keypair(struct kex *kex)
	222	{
	223	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
	224	}
	225
	226	int
	227	kex_ecdh_enc(struct kex kex, const struct sshbuf client_blob,
	228	struct sshbuf server_blobp, struct sshbuf shared_secretp)
	229	{
	230	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
	231	}
	232
	233	int
	234	kex_ecdh_dec(struct kex kex, const struct sshbuf server_blob,
	235	struct sshbuf **shared_secretp)
	236	{
	237	return SSH_ERR_SIGN_ALG_UNSUPPORTED;
	238	}
72ef7c14	239	#endif /* defined(WITH_OPENSSL) && defined(OPENSSL_HAS_ECC) */