mdc.h

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// mdc.h - originally written and placed in the public domain by Wei Dai
 
 
#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)
 
 
template <class B>
struct MDC_Info : public FixedBlockSize<B::DIGESTSIZE>, public FixedKeyLength<B::BLOCKSIZE>
{
        static std::string StaticAlgorithmName() {return std::string("MDC/")+B::StaticAlgorithmName();}
};
 
template <class H>
class MDC : public MDC_Info<H>
{
        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