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/* ====================================================================
* 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) 2000-2002 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
* licensing@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 <openssl/ecdh.h>
#include <string.h>
#include <openssl/bn.h>
#include <openssl/digest.h>
#include <openssl/err.h>
#include <openssl/mem.h>
int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
EC_KEY *priv_key, 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;
const EC_GROUP *group;
int ret = -1;
size_t buflen;
uint8_t *buf = NULL;
if ((ctx = BN_CTX_new()) == NULL) {
goto err;
}
BN_CTX_start(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
priv = EC_KEY_get0_private_key(priv_key);
if (priv == NULL) {
OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE);
goto err;
}
group = EC_KEY_get0_group(priv_key);
tmp = EC_POINT_new(group);
if (tmp == NULL) {
OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv, ctx)) {
OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE);
goto err;
}
buflen = (EC_GROUP_get_degree(group) + 7) / 8;
buf = OPENSSL_malloc(buflen);
if (buf == NULL) {
OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
goto err;
}
if (!BN_bn2bin_padded(buf, buflen, x)) {
OPENSSL_PUT_ERROR(ECDH, ERR_R_INTERNAL_ERROR);
goto err;
}
if (KDF != 0) {
if (KDF(buf, buflen, out, &outlen) == NULL) {
OPENSSL_PUT_ERROR(ECDH, 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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