text: // vmac.h - originally written and placed in the public domain by Wei Dai
  
  /// \file vmac.h
  /// \brief Classes for the VMAC message authentication code
  /// \since Crypto++ 5.5
  
  #ifndef CRYPTOPP_VMAC_H
  #define CRYPTOPP_VMAC_H
  
  #include "cryptlib.h"
  #include "iterhash.h"
  #include "seckey.h"
  
  // Clang 3.3 integrated assembler crash on Linux. Clang 3.4 due to compiler
  // error with .intel_syntax, http://llvm.org/bugs/show_bug.cgi?id=24232
  #if CRYPTOPP_BOOL_X32 || defined(CRYPTOPP_DISABLE_MIXED_ASM)
  # define CRYPTOPP_DISABLE_VMAC_ASM 1
  #endif
  
  NAMESPACE_BEGIN(CryptoPP)
  
  /// \brief VMAC message authentication code base class
  /// \since Crypto++ 5.5
  class VMAC_Base : public IteratedHashBase<word64, MessageAuthenticationCode>
  {
  public:
  	std::string AlgorithmName() const {return std::string("VMAC(") + GetCipher().AlgorithmName() + ")-" + IntToString(DigestSize()*8);}
  	std::string AlgorithmProvider() const {return GetCipher().AlgorithmProvider();}
  	unsigned int IVSize() const {return GetCipher().BlockSize();}
  	unsigned int MinIVLength() const {return 1;}
  	void Resynchronize(const byte *nonce, int length=-1);
  	void GetNextIV(RandomNumberGenerator &rng, byte *IV);
  	unsigned int DigestSize() const {return m_is128 ? 16 : 8;};
  	void UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &params);
  	void TruncatedFinal(byte *mac, size_t size);
  	unsigned int BlockSize() const {return m_L1KeyLength;}
  	ByteOrder GetByteOrder() const {return LITTLE_ENDIAN_ORDER;}
  	unsigned int OptimalDataAlignment() const;
  
  protected:
  	virtual BlockCipher & AccessCipher() =0;
  	virtual int DefaultDigestSize() const =0;
  	const BlockCipher & GetCipher() const {return const_cast<VMAC_Base *>(this)->AccessCipher();}
  	void HashEndianCorrectedBlock(const word64 *data);
  	size_t HashMultipleBlocks(const word64 *input, size_t length);
  	void Init() {}
  	word64* StateBuf() {return NULLPTR;}
  	word64* DataBuf() {return (word64 *)(void*)m_data();}
  
  	void VHASH_Update_SSE2(const word64 *data, size_t blocksRemainingInWord64, int tagPart);
  	template <bool T_128BitTag>
  		void VHASH_Update_Template(const word64 *data, size_t blockRemainingInWord128);
  	void VHASH_Update(const word64 *data, size_t blocksRemainingInWord128);
  
  	CRYPTOPP_BLOCK_1(polyState, word64, (m_is128 ? 8 : 4))
  	CRYPTOPP_BLOCK_2(nhKey, word64, m_L1KeyLength/sizeof(word64) + 2*m_is128)
  	CRYPTOPP_BLOCK_3(data, byte, m_L1KeyLength)
  	CRYPTOPP_BLOCK_4(l3Key, word64, (m_is128 ? 4 : 2))
  	CRYPTOPP_BLOCK_5(nonce, byte, IVSize())
  	CRYPTOPP_BLOCK_6(pad, byte, IVSize())
  	CRYPTOPP_BLOCKS_END(6)
  
  	bool m_is128, m_padCached, m_isFirstBlock;
  	unsigned int m_L1KeyLength;
  };
  
  /// \brief VMAC message authentication code
  /// \tparam T_BlockCipher block cipher
  /// \tparam T_DigestBitSize digest size, in bits
  /// \details VMAC is a block cipher-based message authentication code algorithm
  ///  using a universal hash proposed by Ted Krovetz and Wei Dai in April 2007. The
  ///  algorithm was designed for high performance backed by a formal analysis.
  /// \details The implementation is based on Ted Krovetz's public domain vmac.c
  ///  and <a href="http://tools.ietf.org/html/draft-krovetz-vmac-01">draft-krovetz-vmac-01.txt</a>.
  /// \sa <a href="http://www.cryptolounge.org/wiki/VMAC">VMAC</a>.
  /// \since Crypto++ 5.5
  template <class T_BlockCipher, int T_DigestBitSize = 128>
  class VMAC : public SimpleKeyingInterfaceImpl<VMAC_Base, SameKeyLengthAs<T_BlockCipher, SimpleKeyingInterface::UNIQUE_IV, T_BlockCipher::BLOCKSIZE> >
  {
  public:
  	static std::string StaticAlgorithmName() {return std::string("VMAC(") + T_BlockCipher::StaticAlgorithmName() + ")-" + IntToString(T_DigestBitSize);}
  
  private:
  	BlockCipher & AccessCipher() {return m_cipher;}
  	int DefaultDigestSize() const {return T_DigestBitSize/8;}
  	typename T_BlockCipher::Encryption m_cipher;
  };
  
  NAMESPACE_END
  
  #endif
  