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// shake.h - originally written and placed in the public domain by Jeffrey Walton
/// \file shake.h
/// \brief Classes for SHAKE message digests
/// \sa SHA3, SHAKE128, SHAKE256,
/// <a href="https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf">FIPS 202,
/// SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions</a>
/// \since Crypto++ 8.1
#ifndef CRYPTOPP_SHAKE_H
#define CRYPTOPP_SHAKE_H
#include "cryptlib.h"
#include "secblock.h"
NAMESPACE_BEGIN(CryptoPP)
/// \brief SHAKE message digest base class
/// \details SHAKE is the base class for SHAKE128 and SHAKE258.
/// Library users should instantiate a derived class, and only use SHAKE
/// as a base class reference or pointer.
/// \sa SHA3, SHAKE128, SHAKE256,
/// <a href="https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf">FIPS 202,
/// SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions</a>
/// \since Crypto++ 8.1
class SHAKE : public HashTransformation
{
protected:
/// \brief Construct a SHAKE
/// \param digestSize the digest size, in bytes
/// \details SHAKE is the base class for SHAKE128 and SHAKE256.
/// Library users should instantiate a derived class, and only use SHAKE
/// as a base class reference or pointer.
/// \details This constructor was moved to protected at Crypto++ 8.1
/// because users were attempting to create Keccak objects with it.
/// \since Crypto++ 8.1
SHAKE(unsigned int digestSize) : m_digestSize(digestSize) {Restart();}
public:
unsigned int DigestSize() const {return m_digestSize;}
unsigned int OptimalDataAlignment() const {return GetAlignmentOf<word64>();}
void Update(const byte *input, size_t length);
void Restart();
void TruncatedFinal(byte *hash, size_t size);
protected:
inline unsigned int r() const {return BlockSize();}
FixedSizeSecBlock<word64, 25> m_state;
unsigned int m_digestSize, m_counter;
};
/// \brief SHAKE message digest template
/// \tparam T_Strength the strength of the digest
/// \since Crypto++ 8.1
template<unsigned int T_Strength>
class SHAKE_Final : public SHAKE
{
public:
CRYPTOPP_CONSTANT(DIGESTSIZE = (T_Strength == 128 ? 32 : 64))
CRYPTOPP_CONSTANT(BLOCKSIZE = (T_Strength == 128 ? 1344/8 : 1088/8))
static std::string StaticAlgorithmName()
{ return "SHAKE-" + IntToString(T_Strength); }
/// \brief Construct a SHAKE-X message digest
SHAKE_Final() : SHAKE(DIGESTSIZE) {}
/// \brief Provides the block size of the compression function
/// \return block size of the compression function, in bytes
/// \details BlockSize() will return 0 if the hash is not block based
/// or does not have an equivalent block size. For example, Keccak
/// and SHA-3 do not have a block size, but they do have an equivalent
/// block size called rate expressed as <tt>r</tt>.
unsigned int BlockSize() const { return BLOCKSIZE; }
private:
#if !defined(__BORLANDC__)
// ensure there was no underflow in the math
CRYPTOPP_COMPILE_ASSERT(BLOCKSIZE < 200);
// this is a general expectation by HMAC
CRYPTOPP_COMPILE_ASSERT(BLOCKSIZE > (int)DIGESTSIZE);
#endif
};
/// \brief SHAKE128 message digest
/// \since Crypto++ 8.1
class SHAKE128 : public SHAKE_Final<128> {};
/// \brief SHAKE256 message digest
/// \since Crypto++ 8.1
class SHAKE256 : public SHAKE_Final<256> {};
NAMESPACE_END
#endif
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