tg_windows5.12.6/Telegram/lib_storage/storage/storage_encryption.h

// This file is part of Desktop App Toolkit,
// a set of libraries for developing nice desktop applications.
//
// For license and copyright information please follow this link:
// https://github.com/desktop-app/legal/blob/master/LEGAL
//
#pragma once

#include "base/bytes.h"

namespace Storage {

constexpr auto kSaltSize = size_type(64);

class CtrState {
public:
	static constexpr auto kBlockSize = size_type(16);
	static constexpr auto kKeySize = size_type(32);
	static constexpr auto kIvSize = kBlockSize;

	CtrState(bytes::const_span key, bytes::const_span iv);

	void encrypt(bytes::span data, int64 offset);
	void decrypt(bytes::span data, int64 offset);

private:
	template <typename Method>
	void process(bytes::span data, int64 offset, Method method);

	bytes::array<kIvSize> incrementedIv(int64 blockIndex);

	static constexpr auto EcountSize = kBlockSize;

	bytes::array<kKeySize> _key;
	bytes::array<kIvSize> _iv;

};

class EncryptionKey {
public:
	static constexpr auto kSize = size_type(256);
	static constexpr auto kSize_v2 = size_type(64);

	EncryptionKey() = default;
	explicit EncryptionKey(bytes::vector &&data);

	bool empty() const;
	explicit operator bool() const;

	const bytes::vector &data() const;
	CtrState prepareCtrState(bytes::const_span salt) const;

private:
	bytes::vector _data;

};

} // namespace Storage