| /* |
| * 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_MALLOC_FAILURE); |
| 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) || |
| !BN_mul(x, x, priv_key, ctx)) { |
| ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE); |
| goto err; |
| } |
| priv_key = x; |
| } |
| |
| if ((tmp = EC_POINT_new(group)) == NULL) { |
| ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE); |
| 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) { |
| ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE); |
| 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; |
| } |