~zooko/cryptopp/trunk

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

#ifndef CRYPTOPP_MDC_H

#define CRYPTOPP_MDC_H

/** \file

*/

#include "seckey.h"

#include "misc.h"

NAMESPACE_BEGIN(CryptoPP)

//! _

template <class T>

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

{

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

};

//! <a href="http://www.weidai.com/scan-mirror/cs.html#MDC">MDC</a>

/*! a construction by Peter Gutmann to turn an iterated hash function into a PRF */

template <class T>

class MDC : public MDC_Info<T>

{

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

	{

		typedef typename T::HashWordType HashWordType;

	public:

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

		{

			this->AssertValidKeyLength(length);

			memcpy_s(m_key, m_key.size(), userKey, this->KEYLENGTH);

			T::CorrectEndianess(Key(), Key(), this->KEYLENGTH);

		}

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

		{

			T::CorrectEndianess(Buffer(), (HashWordType *)inBlock, this->BLOCKSIZE);

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

			if (xorBlock)

			{

				T::CorrectEndianess(Buffer(), Buffer(), this->BLOCKSIZE);

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

			}

			else

				T::CorrectEndianess((HashWordType *)outBlock, Buffer(), this->BLOCKSIZE);

		}

		bool IsPermutation() const {return false;}

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

	private:

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

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

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

		// VC60 workaround: bug triggered if using FixedSizeAllocatorWithCleanup

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

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

	};

public:

	//! use BlockCipher interface

	typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption;

};

NAMESPACE_END

#endif