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git-svn-id: svn://svn.code.sf.net/p/cryptopp/code/trunk/c5@2 57ff6487-cd31-0410-9ec3-f628ee90f5f0

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+ // 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 Enc : public BlockCipherBaseTemplate<MDC_Info<T> >
+	{
+		typedef typename T::HashWordType HashWordType;
+
+	public:
+		void UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length)
+		{
+			assert(direction == ENCRYPTION);
+			AssertValidKeyLength(length);
+			memcpy(Key(), userKey, KEYLENGTH);
+			T::CorrectEndianess(Key(), Key(), KEYLENGTH);
+		}
+
+		void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
+		{
+			T::CorrectEndianess(Buffer(), (HashWordType *)inBlock, BLOCKSIZE);
+			T::Transform(Buffer(), Key());
+			if (xorBlock)
+			{
+				T::CorrectEndianess(Buffer(), Buffer(), BLOCKSIZE);
+				xorbuf(outBlock, xorBlock, m_buffer, BLOCKSIZE);
+			}
+			else
+				T::CorrectEndianess((HashWordType *)outBlock, Buffer(), BLOCKSIZE);
+		}
+
+		bool IsPermutation() const {return false;}
+
+		unsigned int GetAlignment() 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 BlockCipherTemplate<ENCRYPTION, Enc> Encryption;
+};
+
+NAMESPACE_END
+
+#endif