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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2010-2022. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* %CopyrightEnd%
*/
#include "ecdh.h"
#include "ec.h"
#if !defined(HAVE_EC)
ERL_NIF_TERM ecdh_compute_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
/* (OtherPublicKey, {CurveDef,CurveName}, My) */
{
return EXCP_NOTSUP_N(env, 0, "EC not supported");
}
#else
# if defined(HAS_3_0_API)
# include "bn.h"
ERL_NIF_TERM ecdh_compute_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
/* (OtherPublicKey, {CurveDef,CurveName}, My) */
{
ERL_NIF_TERM ret = atom_undefined;
ErlNifBinary ret_bin;
size_t sz;
int ret_bin_alloc = 0;
int i = 0, i_key = 0;
OSSL_PARAM params[15];
EVP_PKEY_CTX *own_pctx = NULL, *peer_pctx = NULL, *pctx_gen = NULL;
EVP_PKEY *own_pkey = NULL, *peer_pkey = NULL;
int err;
/**** Fetch parameters ****/
/* Build peer_pkey */
i_key = i;
if (!get_ossl_octet_string_param_from_bin(env, "pub", argv[0], ¶ms[i++]))
assign_goto(ret, err, EXCP_BADARG_N(env, 0, "Bad peer public key; binary expected"));
/* Curve definition/name */
if (!get_curve_definition(env, &ret, argv[1], params, &i, NULL))
goto err;
/* End of params */
params[i++] = OSSL_PARAM_construct_end();
/* Build the remote public key in peer_pkey */
peer_pctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
if (EVP_PKEY_fromdata_init(peer_pctx) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't init fromdata"));
if (EVP_PKEY_fromdata(peer_pctx, &peer_pkey, EVP_PKEY_PUBLIC_KEY, params) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't do fromdata"));
if (!peer_pkey)
assign_goto(ret, err, EXCP_ERROR(env, "No peer_pkey"));
/* Build the local private (and public) key in own_pkey */
/* Just replace the pub key with the priv key in params; the
curve definition is of course the same
*/
if (!get_ossl_BN_param_from_bin(env, "priv", argv[2], ¶ms[i_key]))
assign_goto(ret, err, EXCP_BADARG_N(env, 0, "Bad peer public key; binary expected"));
own_pctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
if (EVP_PKEY_fromdata_init(own_pctx) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't init fromdata"));
if (EVP_PKEY_fromdata(own_pctx, &own_pkey, EVP_PKEY_KEYPAIR, params) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't do fromdata"));
if (!own_pkey)
assign_goto(ret, err, EXCP_ERROR(env, "No own_pkey"));
/**** Derive the common secret from own_pkey and peer_pkey ****/
if (!(pctx_gen = EVP_PKEY_CTX_new(own_pkey, NULL)))
assign_goto(ret, err, EXCP_ERROR(env, "Can't EVP_PKEY_CTX_init"));
if (EVP_PKEY_derive_init(pctx_gen) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't EVP_PKEY_derive_init"));
if ((err = EVP_PKEY_derive_set_peer_ex(pctx_gen, peer_pkey, 0)) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't derive secret or set peer"));
if ((err = EVP_PKEY_derive(pctx_gen, NULL, &sz)) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't get result size"));
if (!enif_alloc_binary(sz, &ret_bin))
assign_goto(ret, err, EXCP_ERROR(env, "Can't allcate binary"));
ret_bin_alloc = 1;
if ((err = EVP_PKEY_derive(pctx_gen, ret_bin.data, &ret_bin.size)) <=0)
assign_goto(ret, err, EXCP_ERROR(env, "Can't get result"));
if (sz != ret_bin.size)
if (!enif_realloc_binary(&ret_bin, ret_bin.size))
assign_goto(ret, err, EXCP_ERROR(env, "Can't realloc binary"));
ret = enif_make_binary(env, &ret_bin);
ret_bin_alloc = 0;
err:
if (ret_bin_alloc) enif_release_binary(&ret_bin);
if (peer_pctx) EVP_PKEY_CTX_free(peer_pctx);
if (peer_pkey) EVP_PKEY_free(peer_pkey);
if (own_pctx) EVP_PKEY_CTX_free(own_pctx);
if (own_pkey) EVP_PKEY_free(own_pkey);
if (pctx_gen) EVP_PKEY_CTX_free(pctx_gen);
return ret;
}
# endif /* HAS_3_0_API */
# if ! defined(HAS_3_0_API)
ERL_NIF_TERM ecdh_compute_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
/* (OtherPublicKey, {CurveDef,_CurveName}, My) */
{
ERL_NIF_TERM ret = atom_undefined;
unsigned char *p;
EC_KEY* key = NULL;
int degree;
size_t field_size;
EC_GROUP *group = NULL;
const BIGNUM *priv_key;
EC_POINT *my_ecpoint = NULL;
EC_KEY *other_ecdh = NULL;
if (!get_ec_key_sz(env, argv[1], argv[2], atom_undefined, &key, NULL)) // my priv key
assign_goto(ret, err, EXCP_BADARG_N(env, 2, "Couldn't get local key"));
if ((group = EC_GROUP_dup(EC_KEY_get0_group(key))) == NULL)
assign_goto(ret, err, EXCP_ERROR(env, "Couldn't duplicate EC key"));
priv_key = EC_KEY_get0_private_key(key);
if (!term2point(env, argv[0], group, &my_ecpoint))
assign_goto(ret, err, EXCP_BADARG_N(env, 0, "Couldn't get ecpoint"));
if ((other_ecdh = EC_KEY_new()) == NULL)
assign_goto(ret, err, EXCP_ERROR(env, "Couldn't allocate EC_KEY"));
if (!EC_KEY_set_group(other_ecdh, group))
assign_goto(ret, err, EXCP_ERROR(env, "Couldn't set group"));
if (!EC_KEY_set_private_key(other_ecdh, priv_key))
assign_goto(ret, err, EXCP_ERROR(env, "Couldn't set private key"));
if ((degree = EC_GROUP_get_degree(group)) <= 0)
assign_goto(ret, err, EXCP_ERROR(env, "Couldn't get degree"));
field_size = (size_t)degree;
if ((p = enif_make_new_binary(env, (field_size+7)/8, &ret)) == NULL)
assign_goto(ret, err, EXCP_ERROR(env, "Couldn't allocate binary"));
if (ECDH_compute_key(p, (field_size+7)/8, my_ecpoint, other_ecdh, NULL) < 1)
assign_goto(ret, err, EXCP_ERROR(env, "Couldn't compute key"));
err:
if (group)
EC_GROUP_free(group);
if (my_ecpoint)
EC_POINT_free(my_ecpoint);
if (other_ecdh)
EC_KEY_free(other_ecdh);
if (key)
EC_KEY_free(key);
return ret;
}
# endif /* ! HAS_3_0_API */
#endif /* HAVE_EC */
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