Chacha.h

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// Honeycomb, Copyright (C) 2015 NewGamePlus Inc.  Distributed under the Boost Software License v1.0.
#pragma once

#include "Honey/Math/Random/Gen.h"

namespace honey
{


class Chacha : public RandomGen
{
public:
    typedef ByteArray<32> Key;
    typedef ByteArray<8> Iv;
    typedef ByteArray<40> Seed;

    struct State
    {
        static const szt coreSize = 16;

        State()                                     : resIdx(coreSize) {}

        uint32 core[coreSize];
        uint32 res[coreSize];
        uint32 resIdx;
    };

    Chacha()                                        { setSeed(); }
    ~Chacha()                                       {}

    void setSeed();

    void setSeed(const Seed& seed);

    virtual uint64 next();

    void setKey(const Key& key);
    void setIv(const Iv& iv);

    void encrypt(ByteBufConst msg, ByteBuf cipher);
    void decrypt(ByteBufConst cipher, ByteBuf msg);

    void setState(const State& state)               { _state = state; }
    State& getState()                               { return _state; }

private:
    void step();

    State _state;

    static const byte _sigma[];
};

}