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120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
/*
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* Copyright 2002-2019 The OpenSSL Project Authors. All Rights Reserved.
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* Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#include <string.h>
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#include <limits.h>
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#include "internal/cryptlib.h"
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#include <openssl/err.h>
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#include <openssl/bn.h>
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#include <openssl/objects.h>
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#include <openssl/ec.h>
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#include "ec_local.h"
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int ossl_ecdh_compute_key(unsigned char **psec, size_t *pseclen,
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const EC_POINT *pub_key, const EC_KEY *ecdh)
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{
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if (ecdh->group->meth->ecdh_compute_key == NULL) {
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ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_CURVE_DOES_NOT_SUPPORT_ECDH);
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return 0;
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}
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return ecdh->group->meth->ecdh_compute_key(psec, pseclen, pub_key, ecdh);
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}
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/*-
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* This implementation is based on the following primitives in the IEEE 1363 standard:
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* - ECKAS-DH1
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* - ECSVDP-DH
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*/
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int ecdh_simple_compute_key(unsigned char **pout, size_t *poutlen,
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const EC_POINT *pub_key, const EC_KEY *ecdh)
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{
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BN_CTX *ctx;
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EC_POINT *tmp = NULL;
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BIGNUM *x = NULL;
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const BIGNUM *priv_key;
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const EC_GROUP *group;
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int ret = 0;
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size_t buflen, len;
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unsigned char *buf = NULL;
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if ((ctx = BN_CTX_new()) == NULL)
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goto err;
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BN_CTX_start(ctx);
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x = BN_CTX_get(ctx);
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if (x == NULL) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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priv_key = EC_KEY_get0_private_key(ecdh);
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if (priv_key == NULL) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_MISSING_PRIVATE_KEY);
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goto err;
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}
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group = EC_KEY_get0_group(ecdh);
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if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) {
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if (!EC_GROUP_get_cofactor(group, x, NULL) ||
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!BN_mul(x, x, priv_key, ctx)) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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priv_key = x;
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}
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if ((tmp = EC_POINT_new(group)) == NULL) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
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goto err;
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}
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if (!EC_POINT_get_affine_coordinates(group, tmp, x, NULL, ctx)) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE);
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goto err;
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}
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buflen = (EC_GROUP_get_degree(group) + 7) / 8;
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len = BN_num_bytes(x);
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if (len > buflen) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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if ((buf = OPENSSL_malloc(buflen)) == NULL) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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memset(buf, 0, buflen - len);
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if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) {
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ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_BN_LIB);
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goto err;
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}
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*pout = buf;
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*poutlen = buflen;
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buf = NULL;
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ret = 1;
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err:
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EC_POINT_clear_free(tmp);
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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OPENSSL_free(buf);
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return ret;
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}
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