2 ecdh.c -- Diffie-Hellman key exchange handling
3 Copyright (C) 2011 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.
24 #include <openssl/err.h>
25 #include <openssl/ec.h>
26 #include <openssl/obj_mac.h>
31 bool ecdh_generate_public(ecdh_t *ecdh, void *pubkey) {
32 *ecdh = EC_KEY_new_by_curve_name(NID_secp521r1);
33 if(!EC_KEY_generate_key(*ecdh)) {
34 logger(DEBUG_ALWAYS, LOG_ERR, "Generating EC key failed: %s", ERR_error_string(ERR_get_error(), NULL));
38 const EC_POINT *point = EC_KEY_get0_public_key(*ecdh);
40 logger(DEBUG_ALWAYS, LOG_ERR, "Getting public key failed: %s", ERR_error_string(ERR_get_error(), NULL));
44 size_t result = EC_POINT_point2oct(EC_KEY_get0_group(*ecdh), point, POINT_CONVERSION_COMPRESSED, pubkey, ECDH_SIZE, NULL);
46 logger(DEBUG_ALWAYS, LOG_ERR, "Converting EC_POINT to binary failed: %s", ERR_error_string(ERR_get_error(), NULL));
53 bool ecdh_compute_shared(ecdh_t *ecdh, const void *pubkey, void *shared) {
54 EC_POINT *point = EC_POINT_new(EC_KEY_get0_group(*ecdh));
56 logger(DEBUG_ALWAYS, LOG_ERR, "EC_POINT_new() failed: %s", ERR_error_string(ERR_get_error(), NULL));
60 int result = EC_POINT_oct2point(EC_KEY_get0_group(*ecdh), point, pubkey, ECDH_SIZE, NULL);
62 logger(DEBUG_ALWAYS, LOG_ERR, "Converting binary to EC_POINT failed: %s", ERR_error_string(ERR_get_error(), NULL));
66 result = ECDH_compute_key(shared, ECDH_SIZE, point, *ecdh, NULL);
72 logger(DEBUG_ALWAYS, LOG_ERR, "Computing Elliptic Curve Diffie-Hellman shared key failed: %s", ERR_error_string(ERR_get_error(), NULL));
79 void ecdh_free(ecdh_t *ecdh) {