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95 lines
3.2 KiB
95 lines
3.2 KiB
/******************************************************************************
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*
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* Copyright 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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******************************************************************************/
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#include "security/ecdh_keys.h"
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/**********************************************************************************************************************
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TODO: We should have random number management in separate file, and we
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should honour all the random number requirements from the spec!!
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**********************************************************************************************************************/
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#include <string.h>
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#include <chrono>
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#include <cstdlib>
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#include "security/ecc/p_256_ecc_pp.h"
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namespace {
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static bool srand_initiated = false;
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template <size_t SIZE>
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static std::array<uint8_t, SIZE> GenerateRandom() {
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if (!srand_initiated) {
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srand_initiated = true;
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// TODO: We need a proper random number generator here.
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// use current time as seed for random generator
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std::srand(std::time(nullptr));
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}
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std::array<uint8_t, SIZE> r;
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for (size_t i = 0; i < SIZE; i++) r[i] = std::rand();
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return r;
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}
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} // namespace
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/*********************************************************************************************************************/
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namespace bluetooth {
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namespace security {
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std::pair<std::array<uint8_t, 32>, EcdhPublicKey> GenerateECDHKeyPair() {
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std::array<uint8_t, 32> private_key = GenerateRandom<32>();
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std::array<uint8_t, 32> private_key_copy = private_key;
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ecc::Point public_key;
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ECC_PointMult(&public_key, &(ecc::curve_p256.G), (uint32_t*)private_key_copy.data());
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EcdhPublicKey pk;
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memcpy(pk.x.data(), public_key.x, 32);
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memcpy(pk.y.data(), public_key.y, 32);
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/* private_key, public key pair */
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return std::make_pair<std::array<uint8_t, 32>, EcdhPublicKey>(std::move(private_key), std::move(pk));
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}
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bool ValidateECDHPoint(EcdhPublicKey pk) {
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ecc::Point public_key;
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memcpy(public_key.x, pk.x.data(), 32);
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memcpy(public_key.y, pk.y.data(), 32);
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memset(public_key.z, 0, 32);
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return ECC_ValidatePoint(public_key);
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}
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std::array<uint8_t, 32> ComputeDHKey(std::array<uint8_t, 32> my_private_key, EcdhPublicKey remote_public_key) {
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ecc::Point peer_publ_key, new_publ_key;
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uint32_t private_key[8];
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memcpy(private_key, my_private_key.data(), 32);
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memcpy(peer_publ_key.x, remote_public_key.x.data(), 32);
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memcpy(peer_publ_key.y, remote_public_key.y.data(), 32);
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memset(peer_publ_key.z, 0, 32);
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peer_publ_key.z[0] = 1;
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ECC_PointMult(&new_publ_key, &peer_publ_key, (uint32_t*)private_key);
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std::array<uint8_t, 32> dhkey;
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memcpy(dhkey.data(), new_publ_key.x, 32);
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return dhkey;
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}
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} // namespace security
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} // namespace bluetooth
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