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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 <limits.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)) {
- const BIGNUM *const priv = EC_KEY_get0_private_key(priv_key);
- if (priv == NULL) {
- OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE);
- return -1;
- }
-
- BN_CTX *ctx = BN_CTX_new();
- if (ctx == NULL) {
- return -1;
- }
- BN_CTX_start(ctx);
-
- int ret = -1;
- size_t buflen = 0;
- uint8_t *buf = NULL;
-
- const EC_GROUP *const group = EC_KEY_get0_group(priv_key);
- EC_POINT *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;
- }
-
- BIGNUM *x = BN_CTX_get(ctx);
- if (!x) {
- OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
- goto err;
- }
-
- if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, NULL, 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 != NULL) {
- if (kdf(buf, buflen, out, &outlen) == NULL) {
- OPENSSL_PUT_ERROR(ECDH, ECDH_R_KDF_FAILED);
- goto err;
- }
- } else {
- /* no KDF, just copy as much as we can */
- if (buflen < outlen) {
- outlen = buflen;
- }
- memcpy(out, buf, outlen);
- }
-
- if (outlen > INT_MAX) {
- OPENSSL_PUT_ERROR(ECDH, ERR_R_OVERFLOW);
- goto err;
- }
-
- ret = (int)outlen;
-
- err:
- OPENSSL_free(buf);
- EC_POINT_free(tmp);
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- return ret;
- }
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