2 ecdh.c -- Diffie-Hellman key exchange handling
3 Copyright (C) 2011-2013 Guus Sliepen <guus@tinc-vpn.org>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License along
16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 #include "../system.h"
22 #include <openssl/err.h>
23 #include <openssl/ec.h>
24 #include <openssl/ecdh.h>
25 #include <openssl/obj_mac.h>
27 #define __TINC_ECDH_INTERNAL__
28 typedef EC_KEY ecdh_t;
31 #include "../logger.h"
33 #include "../xalloc.h"
35 ecdh_t *ecdh_generate_public(void *pubkey) {
36 ecdh_t *ecdh = EC_KEY_new_by_curve_name(NID_secp521r1);
38 logger(DEBUG_ALWAYS, LOG_ERR, "Generating EC key_by_curve_name failed: %s", ERR_error_string(ERR_get_error(), NULL));
42 if(!EC_KEY_generate_key(ecdh)) {
44 logger(DEBUG_ALWAYS, LOG_ERR, "Generating EC key failed: %s", ERR_error_string(ERR_get_error(), NULL));
48 const EC_POINT *point = EC_KEY_get0_public_key(ecdh);
51 logger(DEBUG_ALWAYS, LOG_ERR, "Getting public key failed: %s", ERR_error_string(ERR_get_error(), NULL));
55 size_t result = EC_POINT_point2oct(EC_KEY_get0_group(ecdh), point, POINT_CONVERSION_COMPRESSED, pubkey, ECDH_SIZE, NULL);
58 logger(DEBUG_ALWAYS, LOG_ERR, "Converting EC_POINT to binary failed: %s", ERR_error_string(ERR_get_error(), NULL));
65 bool ecdh_compute_shared(ecdh_t *ecdh, const void *pubkey, void *shared) {
66 EC_POINT *point = EC_POINT_new(EC_KEY_get0_group(ecdh));
68 logger(DEBUG_ALWAYS, LOG_ERR, "EC_POINT_new() failed: %s", ERR_error_string(ERR_get_error(), NULL));
73 int result = EC_POINT_oct2point(EC_KEY_get0_group(ecdh), point, pubkey, ECDH_SIZE, NULL);
77 logger(DEBUG_ALWAYS, LOG_ERR, "Converting binary to EC_POINT failed: %s", ERR_error_string(ERR_get_error(), NULL));
81 result = ECDH_compute_key(shared, ECDH_SIZE, point, ecdh, NULL);
86 logger(DEBUG_ALWAYS, LOG_ERR, "Computing Elliptic Curve Diffie-Hellman shared key failed: %s", ERR_error_string(ERR_get_error(), NULL));
93 void ecdh_free(ecdh_t *ecdh) {