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nearby/fastpair/handshake/fast_pair_data_encryptor_impl.h
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2023-03-23 14:44:42 -07:00

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// Copyright 2023 Google LLC
//
// 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
//
// https://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.
#ifndef THIRD_PARTY_NEARBY_FASTPAIR_HANDSHAKE_FAST_PAIR_DATA_ENCRYPTOR_IMPL_H_
#define THIRD_PARTY_NEARBY_FASTPAIR_HANDSHAKE_FAST_PAIR_DATA_ENCRYPTOR_IMPL_H_
#include <stdint.h>
#include <array>
#include <functional>
#include <memory>
#include <optional>
#include <vector>
#include "absl/functional/any_invocable.h"
#include "fastpair/common/constant.h"
#include "fastpair/common/fast_pair_device.h"
#include "fastpair/crypto/fast_pair_key_pair.h"
#include "fastpair/handshake/fast_pair_data_encryptor.h"
#include "fastpair/repository/device_metadata.h"
namespace nearby {
namespace fastpair {
// Holds a secret key for a device and has methods to encrypt bytes, decrypt
// response and decrypt passkey.
class FastPairDataEncryptorImpl : public FastPairDataEncryptor {
public:
class Factory {
public:
static void CreateAsync(
const FastPairDevice& device,
absl::AnyInvocable<void(std::unique_ptr<FastPairDataEncryptor>)>
on_get_instance_callback);
static void SetFactoryForTesting(Factory* test_factory);
protected:
virtual ~Factory();
virtual void CreateInstance(
const FastPairDevice& device,
absl::AnyInvocable<void(std::unique_ptr<FastPairDataEncryptor>)>
on_get_instance_callback) = 0;
private:
static void CreateAsyncWithKeyExchange(
const FastPairDevice& device,
absl::AnyInvocable<void(std::unique_ptr<FastPairDataEncryptor>)>
on_get_instance_callback);
static void DeviceMetadataRetrieved(
absl::AnyInvocable<void(std::unique_ptr<FastPairDataEncryptor>)>
on_get_instance_callback,
DeviceMetadata& device_metadata);
};
std::array<uint8_t, kAesBlockByteSize> EncryptBytes(
const std::array<uint8_t, kAesBlockByteSize>& bytes_to_encrypt)
const override;
std::optional<std::array<uint8_t, kPublicKeyByteSize>> GetPublicKey()
const override;
void ParseDecryptResponse(
const std::vector<uint8_t>& encrypted_response_bytes,
absl::AnyInvocable<void(const std::optional<DecryptedResponse>)> callback)
override;
void ParseDecryptPasskey(
const std::vector<uint8_t>& encrypted_passkey_bytes,
absl::AnyInvocable<void(const std::optional<DecryptedPasskey>)> callback)
override;
explicit FastPairDataEncryptorImpl(const KeyPair& key_pair);
explicit FastPairDataEncryptorImpl(
const std::array<uint8_t, kSharedSecretKeyByteSize>& secret_key);
~FastPairDataEncryptorImpl() override;
private:
const std::array<uint8_t, kSharedSecretKeyByteSize> shared_secret_key_;
// The public key is only required during initial pairing and optional during
// communication with paired devices.
const std::optional<std::array<uint8_t, kPublicKeyByteSize>> public_key_ =
std::nullopt;
};
} // namespace fastpair
} // namespace nearby
#endif // THIRD_PARTY_NEARBY_FASTPAIR_HANDSHAKE_FAST_PAIR_DATA_ENCRYPTOR_IMPL_H_