random.hh

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/*
 * libkeepass - KeePass key database importer/exporter
 * Copyright (C) 2014 Christian Kindahl
 * Copyright (C) 2024 Dominik Krümpelmann
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#pragma once
#include "cipher.hh"
#include "libkeepass/export.hh"
#include "libkeepass/secure.hh"
 
#include <memory>
#include <random>
#include <vector>
 
namespace keepass {
 
class LIBKEEPASS_API RandomObfuscator {
public:
  enum class Type {
    kSalsa20, 
    kChaCha20 
  };
 
private:
  Type type_ = Type::kSalsa20;
  Salsa20Cipher salsa_cipher_;
  ChaCha20Cipher chacha_cipher_;
 
  std::array<uint8_t, 64> buffer_{};
  std::size_t buffer_pos_ = 64;
 
  void FillBuffer();
  void ProcessBytes(uint8_t* data, std::size_t size);
 
public:
  RandomObfuscator(const std::array<uint8_t, 32>& key, const std::array<uint8_t, 8>& init_vec);
 
  RandomObfuscator(Type type, const std::array<uint8_t, 32>& stream_key);
 
  RandomObfuscator(Type type, const std::vector<uint8_t>& stream_key);
 
  ~RandomObfuscator();
 
 
  std::vector<uint8_t> Process(const std::vector<uint8_t>& data);
 
 
  std::string Process(const std::string& data);
 
 
  secure_string Process(const secure_string& data);
};
 
 
template <std::size_t N> std::array<uint8_t, N> random_array() {
  std::random_device rd;
  std::mt19937 engine(rd());
 
  std::uniform_int_distribution<int> uniform_dist(0, 255);
 
  // Fill block with random values.
  std::array<uint8_t, N> array;
  for (std::size_t i = 0; i < N; ++i)
    array[i] = static_cast<uint8_t>(uniform_dist(engine));
 
  return array;
}
 
} // namespace keepass