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/* crypto/ecdh/ech_ossl.c */
/* ====================================================================
* Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
*
* The Elliptic Curve Public-Key Crypto Library (ECC Code) included
* herein is developed by SUN MICROSYSTEMS, INC., and is contributed
* to the OpenSSL project.
*
* The ECC Code is licensed pursuant to the OpenSSL open source
* license provided below.
*
* The ECDH software is originally written by Douglas Stebila of
* Sun Microsystems Laboratories.
*
*/
/* ====================================================================
* Copyright (c) 1998-2003 The OpenSSL Project. 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.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@OpenSSL.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED 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 OpenSSL PROJECT OR
* ITS CONTRIBUTORS 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.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com).
*
*/
#include <string.h>
#include <limits.h>
#include "cryptlib.h"
#include "ech_locl.h"
#include <openssl/err.h>
#include <openssl/sha.h>
#include <openssl/obj_mac.h>
#include <openssl/bn.h>
static int ecdh_compute_key(void *out, size_t len, const EC_POINT *pub_key,
EC_KEY *ecdh,
void *(*KDF) (const void *in, size_t inlen,
void *out, size_t *outlen));
static ECDH_METHOD openssl_ecdh_meth = {
"OpenSSL ECDH method",
ecdh_compute_key,
#if 0
NULL, /* init */
NULL, /* finish */
#endif
0, /* flags */
NULL /* app_data */
};
const ECDH_METHOD *ECDH_OpenSSL(void)
{
return &openssl_ecdh_meth;
}
/*-
* This implementation is based on the following primitives in the IEEE 1363 standard:
* - ECKAS-DH1
* - ECSVDP-DH
* Finally an optional KDF is applied.
*/
static int ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
EC_KEY *ecdh,
void *(*KDF) (const void *in, size_t inlen,
void *out, size_t *outlen))
{
BN_CTX *ctx;
EC_POINT *tmp = NULL;
BIGNUM *x = NULL, *y = NULL;
const BIGNUM *priv_key;
const EC_GROUP *group;
int ret = -1;
size_t buflen, len;
unsigned char *buf = NULL;
if (outlen > INT_MAX) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); /* sort of,
* anyway */
return -1;
}
if ((ctx = BN_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
priv_key = EC_KEY_get0_private_key(ecdh);
if (priv_key == NULL) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_NO_PRIVATE_VALUE);
goto err;
}
group = EC_KEY_get0_group(ecdh);
if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) {
if (!EC_GROUP_get_cofactor(group, x, ctx) ||
!BN_mul(x, x, priv_key, ctx)) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
goto err;
}
priv_key = x;
}
if ((tmp = EC_POINT_new(group)) == NULL) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
NID_X9_62_prime_field) {
if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
}
#ifndef OPENSSL_NO_EC2M
else {
if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
}
#endif
buflen = (EC_GROUP_get_degree(group) + 7) / 8;
len = BN_num_bytes(x);
if (len > buflen) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_INTERNAL_ERROR);
goto err;
}
if ((buf = OPENSSL_malloc(buflen)) == NULL) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
goto err;
}
memset(buf, 0, buflen - len);
if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_BN_LIB);
goto err;
}
if (KDF != 0) {
if (KDF(buf, buflen, out, &outlen) == NULL) {
ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_KDF_FAILED);
goto err;
}
ret = outlen;
} else {
/* no KDF, just copy as much as we can */
if (outlen > buflen)
outlen = buflen;
memcpy(out, buf, outlen);
ret = outlen;
}
err:
if (tmp)
EC_POINT_free(tmp);
if (ctx)
BN_CTX_end(ctx);
if (ctx)
BN_CTX_free(ctx);
if (buf)
OPENSSL_free(buf);
return (ret);
}
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