148 lines
4.0 KiB
C
148 lines
4.0 KiB
C
/*
|
|
* Copyright 2002-2021 The OpenSSL Project Authors. All Rights Reserved.
|
|
* Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
|
|
*
|
|
* Licensed under the Apache License 2.0 (the "License"). You may not use
|
|
* this file except in compliance with the License. You can obtain a copy
|
|
* in the file LICENSE in the source distribution or at
|
|
* https://www.openssl.org/source/license.html
|
|
*/
|
|
|
|
/*
|
|
* ECDH low level APIs are deprecated for public use, but still ok for
|
|
* internal use.
|
|
*/
|
|
#include "internal/deprecated.h"
|
|
|
|
#include <string.h>
|
|
#include <limits.h>
|
|
|
|
#include "internal/cryptlib.h"
|
|
|
|
#include <openssl/err.h>
|
|
#include <openssl/bn.h>
|
|
#include <openssl/objects.h>
|
|
#include <openssl/ec.h>
|
|
#include "ec_local.h"
|
|
|
|
int ossl_ecdh_compute_key(unsigned char **psec, size_t *pseclen,
|
|
const EC_POINT *pub_key, const EC_KEY *ecdh)
|
|
{
|
|
if (ecdh->group->meth->ecdh_compute_key == NULL) {
|
|
ERR_raise(ERR_LIB_EC, EC_R_CURVE_DOES_NOT_SUPPORT_ECDH);
|
|
return 0;
|
|
}
|
|
|
|
return ecdh->group->meth->ecdh_compute_key(psec, pseclen, pub_key, ecdh);
|
|
}
|
|
|
|
/*-
|
|
* This implementation is based on the following primitives in the
|
|
* IEEE 1363 standard:
|
|
* - ECKAS-DH1
|
|
* - ECSVDP-DH
|
|
*
|
|
* It also conforms to SP800-56A r3
|
|
* See Section 5.7.1.2 "Elliptic Curve Cryptography Cofactor Diffie-Hellman
|
|
* (ECC CDH) Primitive:". The steps listed below refer to SP800-56A.
|
|
*/
|
|
int ossl_ecdh_simple_compute_key(unsigned char **pout, size_t *poutlen,
|
|
const EC_POINT *pub_key, const EC_KEY *ecdh)
|
|
{
|
|
BN_CTX *ctx;
|
|
EC_POINT *tmp = NULL;
|
|
BIGNUM *x = NULL;
|
|
const BIGNUM *priv_key;
|
|
const EC_GROUP *group;
|
|
int ret = 0;
|
|
size_t buflen, len;
|
|
unsigned char *buf = NULL;
|
|
|
|
if ((ctx = BN_CTX_new_ex(ecdh->libctx)) == NULL)
|
|
goto err;
|
|
BN_CTX_start(ctx);
|
|
x = BN_CTX_get(ctx);
|
|
if (x == NULL) {
|
|
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
|
|
goto err;
|
|
}
|
|
|
|
priv_key = EC_KEY_get0_private_key(ecdh);
|
|
if (priv_key == NULL) {
|
|
ERR_raise(ERR_LIB_EC, EC_R_MISSING_PRIVATE_KEY);
|
|
goto err;
|
|
}
|
|
|
|
group = EC_KEY_get0_group(ecdh);
|
|
|
|
/*
|
|
* Step(1) - Compute the point tmp = cofactor * owners_private_key
|
|
* * peer_public_key.
|
|
*/
|
|
if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) {
|
|
if (!EC_GROUP_get_cofactor(group, x, NULL)) {
|
|
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
|
|
goto err;
|
|
}
|
|
if (!BN_mul(x, x, priv_key, ctx)) {
|
|
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
|
|
goto err;
|
|
}
|
|
priv_key = x;
|
|
}
|
|
|
|
if ((tmp = EC_POINT_new(group)) == NULL) {
|
|
ERR_raise(ERR_LIB_EC, ERR_R_EC_LIB);
|
|
goto err;
|
|
}
|
|
|
|
if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) {
|
|
ERR_raise(ERR_LIB_EC, EC_R_POINT_ARITHMETIC_FAILURE);
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* Step(2) : If point tmp is at infinity then clear intermediate values and
|
|
* exit. Note: getting affine coordinates returns 0 if point is at infinity.
|
|
* Step(3a) : Get x-coordinate of point x = tmp.x
|
|
*/
|
|
if (!EC_POINT_get_affine_coordinates(group, tmp, x, NULL, ctx)) {
|
|
ERR_raise(ERR_LIB_EC, EC_R_POINT_ARITHMETIC_FAILURE);
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* Step(3b) : convert x to a byte string, using the field-element-to-byte
|
|
* string conversion routine defined in Appendix C.2
|
|
*/
|
|
buflen = (EC_GROUP_get_degree(group) + 7) / 8;
|
|
len = BN_num_bytes(x);
|
|
if (len > buflen) {
|
|
ERR_raise(ERR_LIB_EC, ERR_R_INTERNAL_ERROR);
|
|
goto err;
|
|
}
|
|
if ((buf = OPENSSL_malloc(buflen)) == NULL)
|
|
goto err;
|
|
|
|
memset(buf, 0, buflen - len);
|
|
if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) {
|
|
ERR_raise(ERR_LIB_EC, ERR_R_BN_LIB);
|
|
goto err;
|
|
}
|
|
|
|
*pout = buf;
|
|
*poutlen = buflen;
|
|
buf = NULL;
|
|
|
|
ret = 1;
|
|
|
|
err:
|
|
/* Step(4) : Destroy all intermediate calculations */
|
|
BN_clear(x);
|
|
EC_POINT_clear_free(tmp);
|
|
BN_CTX_end(ctx);
|
|
BN_CTX_free(ctx);
|
|
OPENSSL_free(buf);
|
|
return ret;
|
|
}
|