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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 CRYPTOPP_NO_VTABLE 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
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