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# lubyrack.h

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    00001 // lubyrack.h - written and placed in the public domain by Wei Dai
    00002
    00003 #ifndef CRYPTOPP_LUBYRACK_H
    00004 #define CRYPTOPP_LUBYRACK_H
    00005
    00006 /** \file */
    00007
    00008 #include "simple.h"
    00009 #include "secblock.h"
    00010
    00011 NAMESPACE_BEGIN(CryptoPP)
    00012
    00013 template <class T> struct DigestSizeDoubleWorkaround    // VC60 workaround
    00014 {
    00015         CRYPTOPP_CONSTANT(RESULT = 2*T::DIGESTSIZE)
    00016 };
    00017
    00018 //! algorithm info
    00019 template <class T>
    00020 struct LR_Info : public VariableKeyLength<16, 0, 2*(INT_MAX/2), 2>, public FixedBlockSize<DigestSizeDoubleWorkaround<T>::RESULT>
    00021 {
    00022         static std::string StaticAlgorithmName() {return std::string("LR/")+T::StaticAlgorithmName();}
    00023 };
    00024
    00025 //! Luby-Rackoff
    00026 template <class T>
    00027 class LR : public LR_Info<T>, public BlockCipherDocumentation
    00028 {
    00029         class CRYPTOPP_NO_VTABLE Base : public BlockCipherImpl<LR_Info<T> >
    00030         {
    00031         public:
    00032                 // VC60 workaround: have to define these functions within class definition
    00033                 void UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &params)
    00034                 {
    00035                         this->AssertValidKeyLength(length);
    00036
    00037                         L = length/2;
    00038                         buffer.New(2*S);
    00039                         digest.New(S);
    00040                         key.Assign(userKey, 2*L);
    00041                 }
    00042
    00043         protected:
    00044                 CRYPTOPP_CONSTANT(S=T::DIGESTSIZE)
    00045                 unsigned int L; // key length / 2
    00046                 SecByteBlock key;
    00047
    00048                 mutable T hm;
    00049                 mutable SecByteBlock buffer, digest;
    00050         };
    00051
    00052         class CRYPTOPP_NO_VTABLE Enc : public Base
    00053         {
    00054         public:
    00055
    00056 #define KL this->key
    00057 #define KR this->key+this->L
    00058 #define BL this->buffer
    00059 #define BR this->buffer+this->S
    00060 #define IL inBlock
    00061 #define IR inBlock+this->S
    00062 #define OL outBlock
    00063 #define OR outBlock+this->S
    00064
    00065                 void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
    00066                 {
    00067                         this->hm.Update(KL, this->L);
    00068                         this->hm.Update(IL, this->S);
    00069                         this->hm.Final(BR);
    00070                         xorbuf(BR, IR, this->S);
    00071
    00072                         this->hm.Update(KR, this->L);
    00073                         this->hm.Update(BR, this->S);
    00074                         this->hm.Final(BL);
    00075                         xorbuf(BL, IL, this->S);
    00076
    00077                         this->hm.Update(KL, this->L);
    00078                         this->hm.Update(BL, this->S);
    00079                         this->hm.Final(this->digest);
    00080                         xorbuf(BR, this->digest, this->S);
    00081
    00082                         this->hm.Update(KR, this->L);
    00083                         this->hm.Update(OR, this->S);
    00084                         this->hm.Final(this->digest);
    00085                         xorbuf(BL, this->digest, this->S);
    00086
    00087                         if (xorBlock)
    00088                                 xorbuf(outBlock, xorBlock, this->buffer, 2*this->S);
    00089                         else
    00090                                 memcpy_s(outBlock, 2*this->S, this->buffer, 2*this->S);
    00091                 }
    00092         };
    00093
    00094         class CRYPTOPP_NO_VTABLE Dec : public Base
    00095         {
    00096         public:
    00097                 void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
    00098                 {
    00099                         this->hm.Update(KR, this->L);
    00100                         this->hm.Update(IR, this->S);
    00101                         this->hm.Final(BL);
    00102                         xorbuf(BL, IL, this->S);
    00103
    00104                         this->hm.Update(KL, this->L);
    00105                         this->hm.Update(BL, this->S);
    00106                         this->hm.Final(BR);
    00107                         xorbuf(BR, IR, this->S);
    00108
    00109                         this->hm.Update(KR, this->L);
    00110                         this->hm.Update(BR, this->S);
    00111                         this->hm.Final(this->digest);
    00112                         xorbuf(BL, this->digest, this->S);
    00113
    00114                         this->hm.Update(KL, this->L);
    00115                         this->hm.Update(OL, this->S);
    00116                         this->hm.Final(this->digest);
    00117                         xorbuf(BR, this->digest, this->S);
    00118
    00119                         if (xorBlock)
    00120                                 xorbuf(outBlock, xorBlock, this->buffer, 2*this->S);
    00121                         else
    00122                                 memcpy(outBlock, this->buffer, 2*this->S);
    00123                 }
    00124 #undef KL
    00125 #undef KR
    00126 #undef BL
    00127 #undef BR
    00128 #undef IL
    00129 #undef IR
    00130 #undef OL
    00131 #undef OR
    00132         };
    00133
    00134 public:
    00135         typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption;
    00136         typedef BlockCipherFinal<DECRYPTION, Dec> Decryption;
    00137 };
    00138
    00139 NAMESPACE_END
    00140
    00141 #endif