2 * Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 /* ====================================================================
11 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
13 * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
14 * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
15 * to the OpenSSL project.
17 * The ECC Code is licensed pursuant to the OpenSSL open source
18 * license provided below.
20 * The ECDH software is originally written by Douglas Stebila of
21 * Sun Microsystems Laboratories.
28 #include "internal/cryptlib.h"
30 #include <openssl/err.h>
31 #include <openssl/bn.h>
32 #include <openssl/objects.h>
33 #include <openssl/ec.h>
36 int ossl_ecdh_compute_key(unsigned char **psec, size_t *pseclen,
37 const EC_POINT *pub_key, const EC_KEY *ecdh)
39 if (ecdh->group->meth->ecdh_compute_key == NULL) {
40 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_CURVE_DOES_NOT_SUPPORT_ECDH);
44 return ecdh->group->meth->ecdh_compute_key(psec, pseclen, pub_key, ecdh);
48 * This implementation is based on the following primitives in the IEEE 1363 standard:
52 int ecdh_simple_compute_key(unsigned char **pout, size_t *poutlen,
53 const EC_POINT *pub_key, const EC_KEY *ecdh)
57 BIGNUM *x = NULL, *y = NULL;
58 const BIGNUM *priv_key;
59 const EC_GROUP *group;
62 unsigned char *buf = NULL;
64 if ((ctx = BN_CTX_new()) == NULL)
70 priv_key = EC_KEY_get0_private_key(ecdh);
71 if (priv_key == NULL) {
72 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_NO_PRIVATE_VALUE);
76 group = EC_KEY_get0_group(ecdh);
78 if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) {
79 if (!EC_GROUP_get_cofactor(group, x, NULL) ||
80 !BN_mul(x, x, priv_key, ctx)) {
81 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
87 if ((tmp = EC_POINT_new(group)) == NULL) {
88 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
92 if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) {
93 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
97 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
98 NID_X9_62_prime_field) {
99 if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
100 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
104 #ifndef OPENSSL_NO_EC2M
106 if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) {
107 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
113 buflen = (EC_GROUP_get_degree(group) + 7) / 8;
114 len = BN_num_bytes(x);
116 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_INTERNAL_ERROR);
119 if ((buf = OPENSSL_malloc(buflen)) == NULL) {
120 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
124 memset(buf, 0, buflen - len);
125 if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) {
126 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_BN_LIB);