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mdc.h

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00001 // mdc.h - written and placed in the public domain by Wei Dai 00002 00003 #ifndef CRYPTOPP_MDC_H 00004 #define CRYPTOPP_MDC_H 00005 00006 /** \file 00007 */ 00008 00009 #include "seckey.h" 00010 #include "misc.h" 00011 00012 NAMESPACE_BEGIN(CryptoPP) 00013 00014 template <class T> 00015 struct MDC_Info : public FixedBlockSize<T::DIGESTSIZE>, public FixedKeyLength<T::BLOCKSIZE> 00016 { 00017 static std::string StaticAlgorithmName() {return std::string("MDC/")+T::StaticAlgorithmName();} 00018 }; 00019 00020 //! <a href="http://www.weidai.com/scan-mirror/cs.html#MDC">MDC</a> 00021 /*! a construction by Peter Gutmann to turn an iterated hash function into a PRF */ 00022 template <class T> 00023 class MDC : public MDC_Info<T> 00024 { 00025 class Enc : public BlockCipherBaseTemplate<MDC_Info<T> > 00026 { 00027 typedef typename T::HashWordType HashWordType; 00028 00029 public: 00030 void UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length) 00031 { 00032 assert(direction == ENCRYPTION); 00033 AssertValidKeyLength(length); 00034 memcpy(Key(), userKey, KEYLENGTH); 00035 T::CorrectEndianess(Key(), Key(), KEYLENGTH); 00036 } 00037 00038 void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const 00039 { 00040 T::CorrectEndianess(Buffer(), (HashWordType *)inBlock, BLOCKSIZE); 00041 T::Transform(Buffer(), Key()); 00042 if (xorBlock) 00043 { 00044 T::CorrectEndianess(Buffer(), Buffer(), BLOCKSIZE); 00045 xorbuf(outBlock, xorBlock, m_buffer, BLOCKSIZE); 00046 } 00047 else 00048 T::CorrectEndianess((HashWordType *)outBlock, Buffer(), BLOCKSIZE); 00049 } 00050 00051 bool IsPermutation() const {return false;} 00052 00053 unsigned int GetAlignment() const {return sizeof(HashWordType);} 00054 00055 private: 00056 HashWordType *Key() {return (HashWordType *)m_key.data();} 00057 const HashWordType *Key() const {return (const HashWordType *)m_key.data();} 00058 HashWordType *Buffer() const {return (HashWordType *)m_buffer.data();} 00059 00060 // VC60 workaround: bug triggered if using FixedSizeAllocatorWithCleanup 00061 FixedSizeSecBlock<byte, MDC_Info<T>::KEYLENGTH, AllocatorWithCleanup<byte> > m_key; 00062 mutable FixedSizeSecBlock<byte, MDC_Info<T>::BLOCKSIZE, AllocatorWithCleanup<byte> > m_buffer; 00063 }; 00064 00065 public: 00066 //! use BlockCipher interface 00067 typedef BlockCipherTemplate<ENCRYPTION, Enc> Encryption; 00068 }; 00069 00070 NAMESPACE_END 00071 00072 #endif

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