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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 //! _ 00015 template <class T> 00016 struct MDC_Info : public FixedBlockSize<T::DIGESTSIZE>, public FixedKeyLength<T::BLOCKSIZE> 00017 { 00018 static std::string StaticAlgorithmName() {return std::string("MDC/")+T::StaticAlgorithmName();} 00019 }; 00020 00021 //! <a href="http://www.weidai.com/scan-mirror/cs.html#MDC">MDC</a> 00022 /*! a construction by Peter Gutmann to turn an iterated hash function into a PRF */ 00023 template <class T> 00024 class MDC : public MDC_Info<T> 00025 { 00026 class CRYPTOPP_NO_VTABLE Enc : public BlockCipherImpl<MDC_Info<T> > 00027 { 00028 typedef typename T::HashWordType HashWordType; 00029 00030 public: 00031 void UncheckedSetKey(CipherDir direction, const byte *userKey, unsigned int length) 00032 { 00033 assert(direction == ENCRYPTION); 00034 this->AssertValidKeyLength(length); 00035 memcpy(Key(), userKey, this->KEYLENGTH); 00036 T::CorrectEndianess(Key(), Key(), this->KEYLENGTH); 00037 } 00038 00039 void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const 00040 { 00041 T::CorrectEndianess(Buffer(), (HashWordType *)inBlock, this->BLOCKSIZE); 00042 T::Transform(Buffer(), Key()); 00043 if (xorBlock) 00044 { 00045 T::CorrectEndianess(Buffer(), Buffer(), this->BLOCKSIZE); 00046 xorbuf(outBlock, xorBlock, m_buffer, this->BLOCKSIZE); 00047 } 00048 else 00049 T::CorrectEndianess((HashWordType *)outBlock, Buffer(), this->BLOCKSIZE); 00050 } 00051 00052 bool IsPermutation() const {return false;} 00053 00054 unsigned int GetAlignment() const {return sizeof(HashWordType);} 00055 00056 private: 00057 HashWordType *Key() {return (HashWordType *)m_key.data();} 00058 const HashWordType *Key() const {return (const HashWordType *)m_key.data();} 00059 HashWordType *Buffer() const {return (HashWordType *)m_buffer.data();} 00060 00061 // VC60 workaround: bug triggered if using FixedSizeAllocatorWithCleanup 00062 FixedSizeSecBlock<byte, MDC_Info<T>::KEYLENGTH, AllocatorWithCleanup<byte> > m_key; 00063 mutable FixedSizeSecBlock<byte, MDC_Info<T>::BLOCKSIZE, AllocatorWithCleanup<byte> > m_buffer; 00064 }; 00065 00066 public: 00067 //! use BlockCipher interface 00068 typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption; 00069 }; 00070 00071 NAMESPACE_END 00072 00073 #endif

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