lubyrack.h

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// lubyrack.h - written and placed in the public domain by Wei Dai

#ifndef CRYPTOPP_LUBYRACK_H
#define CRYPTOPP_LUBYRACK_H

/** \file */

#include "simple.h"
#include "secblock.h"

NAMESPACE_BEGIN(CryptoPP)

template <class T> struct DigestSizeDoubleWorkaround    // VC60 workaround
{
        CRYPTOPP_CONSTANT(RESULT = 2*T::DIGESTSIZE)
};

//! algorithm info
template <class T>
struct LR_Info : public VariableKeyLength<16, 0, 2*(INT_MAX/2), 2>, public FixedBlockSize<DigestSizeDoubleWorkaround<T>::RESULT>
{
        static std::string StaticAlgorithmName() {return std::string("LR/")+T::StaticAlgorithmName();}
};

//! Luby-Rackoff
template <class T>
class LR : public LR_Info<T>, public BlockCipherDocumentation
{
        class CRYPTOPP_NO_VTABLE Base : public BlockCipherImpl<LR_Info<T> >
        {
        public:
                // VC60 workaround: have to define these functions within class definition
                void UncheckedSetKey(const byte *userKey, unsigned int length, const NameValuePairs &params)
                {
                        this->AssertValidKeyLength(length);

                        L = length/2;
                        buffer.New(2*S);
                        digest.New(S);
                        key.Assign(userKey, 2*L);
                }

        protected:
                CRYPTOPP_CONSTANT(S=T::DIGESTSIZE)
                unsigned int L; // key length / 2
                SecByteBlock key;

                mutable T hm;
                mutable SecByteBlock buffer, digest;
        };

        class CRYPTOPP_NO_VTABLE Enc : public Base
        {
        public:

#define KL this->key
#define KR this->key+this->L
#define BL this->buffer
#define BR this->buffer+this->S
#define IL inBlock
#define IR inBlock+this->S
#define OL outBlock
#define OR outBlock+this->S

                void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
                {
                        this->hm.Update(KL, this->L);
                        this->hm.Update(IL, this->S);
                        this->hm.Final(BR);
                        xorbuf(BR, IR, this->S);

                        this->hm.Update(KR, this->L);
                        this->hm.Update(BR, this->S);
                        this->hm.Final(BL);
                        xorbuf(BL, IL, this->S);

                        this->hm.Update(KL, this->L);
                        this->hm.Update(BL, this->S);
                        this->hm.Final(this->digest);
                        xorbuf(BR, this->digest, this->S);

                        this->hm.Update(KR, this->L);
                        this->hm.Update(OR, this->S);
                        this->hm.Final(this->digest);
                        xorbuf(BL, this->digest, this->S);

                        if (xorBlock)
                                xorbuf(outBlock, xorBlock, this->buffer, 2*this->S);
                        else
                                memcpy_s(outBlock, 2*this->S, this->buffer, 2*this->S);
                }
        };

        class CRYPTOPP_NO_VTABLE Dec : public Base
        {
        public:
                void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const
                {
                        this->hm.Update(KR, this->L);
                        this->hm.Update(IR, this->S);
                        this->hm.Final(BL);
                        xorbuf(BL, IL, this->S);

                        this->hm.Update(KL, this->L);
                        this->hm.Update(BL, this->S);
                        this->hm.Final(BR);
                        xorbuf(BR, IR, this->S);

                        this->hm.Update(KR, this->L);
                        this->hm.Update(BR, this->S);
                        this->hm.Final(this->digest);
                        xorbuf(BL, this->digest, this->S);

                        this->hm.Update(KL, this->L);
                        this->hm.Update(OL, this->S);
                        this->hm.Final(this->digest);
                        xorbuf(BR, this->digest, this->S);

                        if (xorBlock)
                                xorbuf(outBlock, xorBlock, this->buffer, 2*this->S);
                        else
                                memcpy(outBlock, this->buffer, 2*this->S);
                }
#undef KL
#undef KR
#undef BL
#undef BR
#undef IL
#undef IR
#undef OL
#undef OR
        };

public:
        typedef BlockCipherFinal<ENCRYPTION, Enc> Encryption;
        typedef BlockCipherFinal<DECRYPTION, Dec> Decryption;
};

NAMESPACE_END

#endif

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