1 /* ====================================================================
2 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
4 * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
5 * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
6 * to the OpenSSL project.
8 * The ECC Code is licensed pursuant to the OpenSSL open source
9 * license provided below.
11 * The ECDH software is originally written by Douglas Stebila of
12 * Sun Microsystems Laboratories.
15 /* ====================================================================
16 * Copyright (c) 1998-2003 The OpenSSL Project. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
25 * 2. Redistributions in binary form must reproduce the above copyright
26 * notice, this list of conditions and the following disclaimer in
27 * the documentation and/or other materials provided with the
30 * 3. All advertising materials mentioning features or use of this
31 * software must display the following acknowledgment:
32 * "This product includes software developed by the OpenSSL Project
33 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
35 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
36 * endorse or promote products derived from this software without
37 * prior written permission. For written permission, please contact
38 * openssl-core@OpenSSL.org.
40 * 5. Products derived from this software may not be called "OpenSSL"
41 * nor may "OpenSSL" appear in their names without prior written
42 * permission of the OpenSSL Project.
44 * 6. Redistributions of any form whatsoever must retain the following
46 * "This product includes software developed by the OpenSSL Project
47 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
49 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
50 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
52 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
53 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
54 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
55 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
56 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
58 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
59 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
60 * OF THE POSSIBILITY OF SUCH DAMAGE.
61 * ====================================================================
63 * This product includes cryptographic software written by Eric Young
64 * (eay@cryptsoft.com). This product includes software written by Tim
65 * Hudson (tjh@cryptsoft.com).
72 #include "internal/cryptlib.h"
74 #include <openssl/err.h>
75 #include <openssl/bn.h>
76 #include <openssl/objects.h>
77 #include <openssl/ec.h>
81 * This implementation is based on the following primitives in the IEEE 1363 standard:
84 * Finally an optional KDF is applied.
86 int ossl_ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
88 void *(*KDF) (const void *in, size_t inlen,
89 void *out, size_t *outlen))
93 BIGNUM *x = NULL, *y = NULL;
94 const BIGNUM *priv_key;
95 const EC_GROUP *group;
98 unsigned char *buf = NULL;
100 if (outlen > INT_MAX) {
101 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); /* sort of,
106 if ((ctx = BN_CTX_new()) == NULL)
112 priv_key = EC_KEY_get0_private_key(ecdh);
113 if (priv_key == NULL) {
114 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_NO_PRIVATE_VALUE);
118 group = EC_KEY_get0_group(ecdh);
120 if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) {
121 if (!EC_GROUP_get_cofactor(group, x, ctx) ||
122 !BN_mul(x, x, priv_key, ctx)) {
123 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
129 if ((tmp = EC_POINT_new(group)) == NULL) {
130 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
134 if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) {
135 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
139 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
140 NID_X9_62_prime_field) {
141 if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
142 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
146 #ifndef OPENSSL_NO_EC2M
148 if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) {
149 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
155 buflen = (EC_GROUP_get_degree(group) + 7) / 8;
156 len = BN_num_bytes(x);
158 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, ERR_R_INTERNAL_ERROR);
161 if ((buf = OPENSSL_malloc(buflen)) == NULL) {
162 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
166 memset(buf, 0, buflen - len);
167 if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) {
168 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, ERR_R_BN_LIB);
173 if (KDF(buf, buflen, out, &outlen) == NULL) {
174 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_KDF_FAILED);
179 /* no KDF, just copy as much as we can */
182 memcpy(out, buf, outlen);