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94 lines
3.5 KiB
94 lines
3.5 KiB
5 years ago
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// eprecomp.h - written and placed in the public domain by Wei Dai
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//! \file eprecomp.h
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//! \brief Classes for precomputation in a group
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#ifndef CRYPTOPP_EPRECOMP_H
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#define CRYPTOPP_EPRECOMP_H
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#include "cryptlib.h"
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#include "integer.h"
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#include "algebra.h"
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#include "stdcpp.h"
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NAMESPACE_BEGIN(CryptoPP)
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template <class T>
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class DL_GroupPrecomputation
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{
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public:
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typedef T Element;
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virtual bool NeedConversions() const {return false;}
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virtual Element ConvertIn(const Element &v) const {return v;}
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virtual Element ConvertOut(const Element &v) const {return v;}
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virtual const AbstractGroup<Element> & GetGroup() const =0;
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virtual Element BERDecodeElement(BufferedTransformation &bt) const =0;
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virtual void DEREncodeElement(BufferedTransformation &bt, const Element &P) const =0;
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#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
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virtual ~DL_GroupPrecomputation() {}
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#endif
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};
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template <class T>
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class DL_FixedBasePrecomputation
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{
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public:
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typedef T Element;
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virtual bool IsInitialized() const =0;
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virtual void SetBase(const DL_GroupPrecomputation<Element> &group, const Element &base) =0;
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virtual const Element & GetBase(const DL_GroupPrecomputation<Element> &group) const =0;
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virtual void Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage) =0;
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virtual void Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) =0;
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virtual void Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) const =0;
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virtual Element Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const =0;
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virtual Element CascadeExponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent, const DL_FixedBasePrecomputation<Element> &pc2, const Integer &exponent2) const =0;
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#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
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virtual ~DL_FixedBasePrecomputation() {}
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#endif
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};
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template <class T>
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class DL_FixedBasePrecomputationImpl : public DL_FixedBasePrecomputation<T>
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{
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public:
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typedef T Element;
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DL_FixedBasePrecomputationImpl() : m_windowSize(0) {}
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// DL_FixedBasePrecomputation
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bool IsInitialized() const
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{return !m_bases.empty();}
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void SetBase(const DL_GroupPrecomputation<Element> &group, const Element &base);
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const Element & GetBase(const DL_GroupPrecomputation<Element> &group) const
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{return group.NeedConversions() ? m_base : m_bases[0];}
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void Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage);
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void Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation);
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void Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) const;
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Element Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const;
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Element CascadeExponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent, const DL_FixedBasePrecomputation<Element> &pc2, const Integer &exponent2) const;
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#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
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virtual ~DL_FixedBasePrecomputationImpl() {}
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#endif
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private:
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void PrepareCascade(const DL_GroupPrecomputation<Element> &group, std::vector<BaseAndExponent<Element> > &eb, const Integer &exponent) const;
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Element m_base;
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unsigned int m_windowSize;
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Integer m_exponentBase; // what base to represent the exponent in
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std::vector<Element> m_bases; // precalculated bases
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};
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NAMESPACE_END
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#ifdef CRYPTOPP_MANUALLY_INSTANTIATE_TEMPLATES
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#include "eprecomp.cpp"
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#endif
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#endif
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