1 // mdc.h - written and placed in the public domain by Wei Dai 2 3#ifndef CRYPTOPP_MDC_H 4#define CRYPTOPP_MDC_H 5 6/** \file 7*/ 8 9#include "seckey.h" 10#include "misc.h" 11 12NAMESPACE_BEGIN(CryptoPP) 13 14//! _ 15template <class T> 16struct MDC_Info : public FixedBlockSize<T::DIGESTSIZE>, public FixedKeyLength<T::BLOCKSIZE> 17{ 18 static std::string StaticAlgorithmName() {return std::string("MDC/")+T::StaticAlgorithmName();} 19}; 20 21//! <a href="http://www.weidai.com/scan-mirror/cs.html#MDC">MDC</a> 22/*! a construction by Peter Gutmann to turn an iterated hash function into a PRF */ 23template <class T> 24class MDC : public MDC_Info<T> 25{ 26 class CRYPTOPP_NO_VTABLE Enc : public BlockCipherImpl<MDC_Info<T> > 27 { 28 typedef typename T::HashWordType HashWordType; 29 30 public: 31 void UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs ¶ms) 32 { 33 this->AssertValidKeyLength(length); 34 memcpy_s(m_key, m_key.size(), userKey, this->KEYLENGTH); 35 T::CorrectEndianess(Key(), Key(), this->KEYLENGTH); 36 } 37 38 void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const 39 { 40 T::CorrectEndianess(Buffer(), (HashWordType *)inBlock, this->BLOCKSIZE); 41 T::Transform(Buffer(), Key()); 42 if (xorBlock) 43 { 44 T::CorrectEndianess(Buffer(), Buffer(), this->BLOCKSIZE); 45 xorbuf(outBlock, xorBlock, m_buffer, this->BLOCKSIZE); 46 } 47 else 48 T::CorrectEndianess((HashWordType *)outBlock, Buffer(), this->BLOCKSIZE); 49 } 50 51 bool IsPermutation() const {return false;} 52 53 unsigned int OptimalDataAlignment() const {return sizeof(HashWordType);} 54 55 private: 56 HashWordType *Key() {return (HashWordType *)m_key.data();} 57 const HashWordType *Key() const {return (const HashWordType *)m_key.data();} 58 HashWordType *Buffer() const {return (HashWordType *)m_buffer.data();} 59 60 // VC60 workaround: bug triggered if using FixedSizeAllocatorWithCleanup 61 FixedSizeSecBlock<byte, MDC_Info<T>::KEYLENGTH, AllocatorWithCleanup<byte> > m_key; 62 mutable FixedSizeSecBlock<byte, MDC_Info<T>::BLOCKSIZE, AllocatorWithCleanup<byte> > m_buffer; 63 }; 64 65public: 66 //! use BlockCipher interface 67 typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption; 68}; 69 70NAMESPACE_END 71 72#endif 73