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

/// \file mdc.h

/// \brief Classes for the MDC message digest

#ifndef CRYPTOPP_MDC_H

#define CRYPTOPP_MDC_H

#include "seckey.h"

#include "secblock.h"

#include "misc.h"

// GCC cast warning

#define HashWordPtr(x) ((HashWordType*)(void*)(x))

#define ConstHashWordPtr(x) ((const HashWordType*)(const void*)(x))

NAMESPACE_BEGIN(CryptoPP)

/// \tparam B BlockCipher derived class

/// \brief MDC_Info cipher information

template <class B>

struct MDC_Info : public FixedBlockSize<B::DIGESTSIZE>, public FixedKeyLength<B::BLOCKSIZE>

{

  static std::string StaticAlgorithmName() {return std::string("MDC/")+B::StaticAlgorithmName();}

};

/// \brief MDC cipher

/// \tparam H HashTransformation derived class

/// \details MDC() is a construction by Peter Gutmann to turn an iterated hash function into a PRF

/// \sa <a href="http://www.cryptopp.com/wiki/MDC">MDC</a>

template <class H>

class MDC : public MDC_Info<H>

{

  /// \brief MDC cipher encryption operation

  class CRYPTOPP_NO_VTABLE Enc : public BlockCipherImpl<MDC_Info<H> >

  {

    typedef typename H::HashWordType HashWordType;

  public:

    void UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &params)

    {

      CRYPTOPP_UNUSED(params);

      this->AssertValidKeyLength(length);

      ConditionalByteReverse(BIG_ENDIAN_ORDER, Key(), ConstHashWordPtr(userKey), this->KEYLENGTH);

    }

    void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const

    {

      ConditionalByteReverse(BIG_ENDIAN_ORDER, Buffer(), ConstHashWordPtr(inBlock), this->BLOCKSIZE);

      H::Transform(Buffer(), Key());

      if (xorBlock)

      {

        ConditionalByteReverse(BIG_ENDIAN_ORDER, Buffer(), Buffer(), this->BLOCKSIZE);

        xorbuf(outBlock, xorBlock, m_buffer, this->BLOCKSIZE);

      }

      else

      {

        ConditionalByteReverse(BIG_ENDIAN_ORDER, HashWordPtr(outBlock), Buffer(), this->BLOCKSIZE);

      }

    }

    bool IsPermutation() const {return false;}

    unsigned int OptimalDataAlignment() const {return sizeof(HashWordType);}

  private:

    HashWordType *Key() {return HashWordPtr(m_key.data());}

    const HashWordType *Key() const {return ConstHashWordPtr(m_key.data());}

    HashWordType *Buffer() const {return HashWordPtr(m_buffer.data());}

    // VC60 workaround: bug triggered if using FixedSizeAllocatorWithCleanup

    FixedSizeSecBlock<byte, MDC_Info<H>::KEYLENGTH, AllocatorWithCleanup<byte> > m_key;

    mutable FixedSizeSecBlock<byte, MDC_Info<H>::BLOCKSIZE, AllocatorWithCleanup<byte> > m_buffer;

  };

public:

  // use BlockCipher interface

  typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption;

};

NAMESPACE_END

#endif