gf256.h

#ifndef CRYPTOPP_GF256_H
#define CRYPTOPP_GF256_H

#include "cryptlib.h"

NAMESPACE_BEGIN(CryptoPP)

//! GF(256) with polynomial basis
class GF256
{
public:
        typedef byte Element;
        typedef int RandomizationParameter;

        GF256(byte modulus) : m_modulus(modulus) {}

        Element RandomElement(RandomNumberGenerator &rng, int ignored = 0) const
                {return rng.GenerateByte();}

        bool Equal(Element a, Element b) const
                {return a==b;}

        Element Zero() const
                {return 0;}

        Element Add(Element a, Element b) const
                {return a^b;}

        Element& Accumulate(Element &a, Element b) const
                {return a^=b;}

        Element Inverse(Element a) const
                {return a;}

        Element Subtract(Element a, Element b) const
                {return a^b;}

        Element& Reduce(Element &a, Element b) const
                {return a^=b;}

        Element Double(Element a) const
                {return 0;}

        Element One() const
                {return 1;}

        Element Multiply(Element a, Element b) const;

        Element Square(Element a) const
                {return Multiply(a, a);}

        bool IsUnit(Element a) const
                {return a != 0;}

        Element MultiplicativeInverse(Element a) const;

        Element Divide(Element a, Element b) const
                {return Multiply(a, MultiplicativeInverse(b));}

private:
        word m_modulus;
};

NAMESPACE_END

#endif

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