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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 <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, len;
- 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_compute_key, 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, ECDH_compute_key, ERR_R_MALLOC_FAILURE);
- goto err;
- }
-
- if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv, ctx)) {
- OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ECDH_R_POINT_ARITHMETIC_FAILURE);
- goto err;
- }
-
- if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
- OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ECDH_R_POINT_ARITHMETIC_FAILURE);
- goto err;
- }
-
- buflen = (EC_GROUP_get_degree(group) + 7) / 8;
- len = BN_num_bytes(x);
- if (len > buflen) {
- OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ERR_R_INTERNAL_ERROR);
- goto err;
- }
- buf = OPENSSL_malloc(buflen);
- if (buf == NULL) {
- OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ERR_R_MALLOC_FAILURE);
- goto err;
- }
-
- memset(buf, 0, buflen - len);
- if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) {
- OPENSSL_PUT_ERROR(ECDH, ECDH_compute_key, ERR_R_BN_LIB);
- goto err;
- }
-
- if (KDF != 0) {
- if (KDF(buf, buflen, out, &outlen) == NULL) {
- OPENSSL_PUT_ERROR(ECDH, 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;
- }
-
- /* Key derivation function from X9.62/SECG */
- /* Way more than we will ever need */
- #define ECDH_KDF_MAX (1 << 30)
-
- int ECDH_KDF_X9_62(uint8_t *out, size_t outlen, const uint8_t *Z,
- size_t Zlen, const uint8_t *sinfo, size_t sinfolen,
- const EVP_MD *md) {
- EVP_MD_CTX mctx;
- int rv = 0;
- unsigned int i;
- size_t mdlen;
- uint8_t ctr[4];
-
- if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX || Zlen > ECDH_KDF_MAX) {
- return 0;
- }
- mdlen = EVP_MD_size(md);
- EVP_MD_CTX_init(&mctx);
-
- for (i = 1;; i++) {
- uint8_t mtmp[EVP_MAX_MD_SIZE];
- EVP_DigestInit_ex(&mctx, md, NULL);
- ctr[3] = i & 0xFF;
- ctr[2] = (i >> 8) & 0xFF;
- ctr[1] = (i >> 16) & 0xFF;
- ctr[0] = (i >> 24) & 0xFF;
- if (!EVP_DigestUpdate(&mctx, Z, Zlen) ||
- !EVP_DigestUpdate(&mctx, ctr, sizeof(ctr)) ||
- !EVP_DigestUpdate(&mctx, sinfo, sinfolen)) {
- goto err;
- }
-
- if (outlen >= mdlen) {
- if (!EVP_DigestFinal(&mctx, out, NULL)) {
- goto err;
- }
- outlen -= mdlen;
- if (outlen == 0) {
- break;
- }
- out += mdlen;
- } else {
- if (!EVP_DigestFinal(&mctx, mtmp, NULL)) {
- goto err;
- }
- memcpy(out, mtmp, outlen);
- OPENSSL_cleanse(mtmp, mdlen);
- break;
- }
- }
- rv = 1;
-
- err:
- EVP_MD_CTX_cleanup(&mctx);
- return rv;
- }
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