2 * Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
5 * Licensed under the OpenSSL license (the "License"). You may not use
6 * this file except in compliance with the License. You can obtain a copy
7 * in the file LICENSE in the source distribution or at
8 * https://www.openssl.org/source/license.html
14 #include "internal/cryptlib.h"
16 #include <openssl/err.h>
17 #include <openssl/bn.h>
18 #include <openssl/objects.h>
19 #include <openssl/ec.h>
22 int ossl_ecdh_compute_key(unsigned char **psec
, size_t *pseclen
,
23 const EC_POINT
*pub_key
, const EC_KEY
*ecdh
)
25 if (ecdh
->group
->meth
->ecdh_compute_key
== NULL
) {
26 ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY
, EC_R_CURVE_DOES_NOT_SUPPORT_ECDH
);
30 return ecdh
->group
->meth
->ecdh_compute_key(psec
, pseclen
, pub_key
, ecdh
);
34 * This implementation is based on the following primitives in the IEEE 1363 standard:
38 int ecdh_simple_compute_key(unsigned char **pout
, size_t *poutlen
,
39 const EC_POINT
*pub_key
, const EC_KEY
*ecdh
)
43 BIGNUM
*x
= NULL
, *y
= NULL
;
44 const BIGNUM
*priv_key
;
45 const EC_GROUP
*group
;
48 unsigned char *buf
= NULL
;
50 if ((ctx
= BN_CTX_new()) == NULL
)
56 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, ERR_R_MALLOC_FAILURE
);
60 priv_key
= EC_KEY_get0_private_key(ecdh
);
61 if (priv_key
== NULL
) {
62 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, EC_R_NO_PRIVATE_VALUE
);
66 group
= EC_KEY_get0_group(ecdh
);
68 if (EC_KEY_get_flags(ecdh
) & EC_FLAG_COFACTOR_ECDH
) {
69 if (!EC_GROUP_get_cofactor(group
, x
, NULL
) ||
70 !BN_mul(x
, x
, priv_key
, ctx
)) {
71 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, ERR_R_MALLOC_FAILURE
);
77 if ((tmp
= EC_POINT_new(group
)) == NULL
) {
78 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, ERR_R_MALLOC_FAILURE
);
82 if (!EC_POINT_mul(group
, tmp
, NULL
, pub_key
, priv_key
, ctx
)) {
83 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, EC_R_POINT_ARITHMETIC_FAILURE
);
87 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group
)) ==
88 NID_X9_62_prime_field
) {
89 if (!EC_POINT_get_affine_coordinates_GFp(group
, tmp
, x
, y
, ctx
)) {
90 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, EC_R_POINT_ARITHMETIC_FAILURE
);
94 #ifndef OPENSSL_NO_EC2M
96 if (!EC_POINT_get_affine_coordinates_GF2m(group
, tmp
, x
, y
, ctx
)) {
97 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, EC_R_POINT_ARITHMETIC_FAILURE
);
103 buflen
= (EC_GROUP_get_degree(group
) + 7) / 8;
104 len
= BN_num_bytes(x
);
106 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, ERR_R_INTERNAL_ERROR
);
109 if ((buf
= OPENSSL_malloc(buflen
)) == NULL
) {
110 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, ERR_R_MALLOC_FAILURE
);
114 memset(buf
, 0, buflen
- len
);
115 if (len
!= (size_t)BN_bn2bin(x
, buf
+ buflen
- len
)) {
116 ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY
, ERR_R_BN_LIB
);