// onetimepad.hpp
//
// Copyright (C) 2006-2020 MicroNeil Research Corporation.
//
// This software is released under the MIT license. See LICENSE.TXT.
//
// This module leverages the Mangler encryption engine to create
// cryptographically strong one-time pads and random numbers upon request.
// The engine is seeded by /dev/urandom on *nix machines and by CryptGenRandom
// on win32 machines. Additionally, each call to get new data introduces a
// small amount of entropy based on the jitter in timing between calls and the
// amount of time the application has been running since the generator was
// started. Additional entropy can be provided by the application or again from
// one of the core entropy generators (/dev/urandom or CryptGenRandom).

#pragma once

#include <vector>
#include "mangler.hpp"

namespace codedweller {

typedef std::vector<unsigned char> PadBuffer;

class OneTimePad {                                                              // One Time Pad generator.
  private:
    MANGLER PadGenerator;                                                       // MANGLER as a PRNG.
    void addLightweightEntropy();                                               // Add light weight entropy bits.
    PadBuffer Entropy(int Length = 1024);                                       // System entropy source.

    void* fill(void* Object, int Size);                                         // Internal method to fill an object.

    bool StrongEntropyFlag;                                                     // True if strong entropy is used.

  public:
    OneTimePad();                                                               // Constructor initializes w/ Entropy.

    bool isStrong();                                                            // True if strong entropy is available.

    PadBuffer Pad(int Length);                                                  // Get a pad of Length.
    void addEntropy();                                                          // Add entropy from the system source.
    void addEntropy(PadBuffer Entropy);                                         // Add entropy from this source.

    template <typename T>                                                       // Fill any kind of object
      T& fill(T& Object) {                                                      // with random bytes.
        fill((void*) &Object, sizeof(Object));                                  // Get a void ptr to it, fill it,
        return Object;                                                          // and return it to the caller.
    }

};

} // End namespace codedweller