keccak.h

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// keccak.h - written and placed in the public domain by Wei Dai


#ifndef CRYPTOPP_KECCAK_H
#define CRYPTOPP_KECCAK_H

#include "cryptlib.h"
#include "secblock.h"

NAMESPACE_BEGIN(CryptoPP)

class Keccak : public HashTransformation
{
public:
        Keccak(unsigned int digestSize) : m_digestSize(digestSize) {Restart();}
        unsigned int DigestSize() const {return m_digestSize;}
        std::string AlgorithmName() const {return "Keccak-" + IntToString(m_digestSize*8);}
        CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "Keccak"; }
        unsigned int OptimalDataAlignment() const {return GetAlignmentOf<word64>();}

        void Update(const byte *input, size_t length);
        void Restart();
        void TruncatedFinal(byte *hash, size_t size);

        //unsigned int BlockSize() const { return r(); } // that's the idea behind it

protected:
        inline unsigned int r() const {return 200 - 2 * m_digestSize;}

        FixedSizeSecBlock<word64, 25> m_state;
        unsigned int m_digestSize, m_counter;
};

template<unsigned int T_DigestSize>
class Keccak_Final : public Keccak
{
public:
        CRYPTOPP_CONSTANT(DIGESTSIZE = T_DigestSize)
        CRYPTOPP_CONSTANT(BLOCKSIZE = 200 - 2 * DIGESTSIZE)

                
        Keccak_Final() : Keccak(DIGESTSIZE) {}
        static std::string StaticAlgorithmName() { return "Keccak-" + IntToString(DIGESTSIZE * 8); }
        unsigned int BlockSize() const { return BLOCKSIZE; }
private:
        CRYPTOPP_COMPILE_ASSERT(BLOCKSIZE < 200); // ensure there was no underflow in the math
        CRYPTOPP_COMPILE_ASSERT(BLOCKSIZE > (int)T_DigestSize); // this is a general expectation by HMAC
};

typedef Keccak_Final<28> Keccak_224;
typedef Keccak_Final<32> Keccak_256;
typedef Keccak_Final<48> Keccak_384;
typedef Keccak_Final<64> Keccak_512;

NAMESPACE_END

#endif