| 1 | // eprecomp.h - written and placed in the public domain by Wei Dai |
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| 2 | |
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| 3 | //! \file eprecomp.h |
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| 4 | //! \brief Classes for precomputation in a group |
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| 5 | |
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| 6 | #ifndef CRYPTOPP_EPRECOMP_H |
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| 7 | #define CRYPTOPP_EPRECOMP_H |
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| 8 | |
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| 9 | #include "cryptlib.h" |
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| 10 | #include "integer.h" |
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| 11 | #include "algebra.h" |
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| 12 | #include "stdcpp.h" |
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| 13 | |
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| 14 | NAMESPACE_BEGIN(CryptoPP) |
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| 15 | |
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| 16 | template <class T> |
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| 17 | class DL_GroupPrecomputation |
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| 18 | { |
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| 19 | public: |
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| 20 | typedef T Element; |
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| 21 | |
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| 22 | virtual bool NeedConversions() const {return false;} |
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| 23 | virtual Element ConvertIn(const Element &v) const {return v;} |
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| 24 | virtual Element ConvertOut(const Element &v) const {return v;} |
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| 25 | virtual const AbstractGroup<Element> & GetGroup() const =0; |
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| 26 | virtual Element BERDecodeElement(BufferedTransformation &bt) const =0; |
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| 27 | virtual void DEREncodeElement(BufferedTransformation &bt, const Element &P) const =0; |
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| 28 | |
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| 29 | #ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562 |
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| 30 | virtual ~DL_GroupPrecomputation() {} |
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| 31 | #endif |
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| 32 | }; |
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| 33 | |
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| 34 | template <class T> |
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| 35 | class DL_FixedBasePrecomputation |
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| 36 | { |
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| 37 | public: |
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| 38 | typedef T Element; |
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| 39 | |
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| 40 | virtual bool IsInitialized() const =0; |
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| 41 | virtual void SetBase(const DL_GroupPrecomputation<Element> &group, const Element &base) =0; |
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| 42 | virtual const Element & GetBase(const DL_GroupPrecomputation<Element> &group) const =0; |
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| 43 | virtual void Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage) =0; |
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| 44 | virtual void Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) =0; |
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| 45 | virtual void Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) const =0; |
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| 46 | virtual Element Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const =0; |
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| 47 | 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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| 48 | |
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| 49 | #ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562 |
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| 50 | virtual ~DL_FixedBasePrecomputation() {} |
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| 51 | #endif |
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| 52 | }; |
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| 53 | |
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| 54 | template <class T> |
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| 55 | class DL_FixedBasePrecomputationImpl : public DL_FixedBasePrecomputation<T> |
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| 56 | { |
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| 57 | public: |
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| 58 | typedef T Element; |
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| 59 | |
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| 60 | DL_FixedBasePrecomputationImpl() : m_windowSize(0) {} |
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| 61 | |
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| 62 | // DL_FixedBasePrecomputation |
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| 63 | bool IsInitialized() const |
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| 64 | {return !m_bases.empty();} |
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| 65 | void SetBase(const DL_GroupPrecomputation<Element> &group, const Element &base); |
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| 66 | const Element & GetBase(const DL_GroupPrecomputation<Element> &group) const |
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| 67 | {return group.NeedConversions() ? m_base : m_bases[0];} |
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| 68 | void Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage); |
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| 69 | void Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation); |
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| 70 | void Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) const; |
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| 71 | Element Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const; |
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| 72 | Element CascadeExponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent, const DL_FixedBasePrecomputation<Element> &pc2, const Integer &exponent2) const; |
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| 73 | |
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| 74 | #ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562 |
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| 75 | virtual ~DL_FixedBasePrecomputationImpl() {} |
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| 76 | #endif |
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| 77 | |
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| 78 | private: |
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| 79 | void PrepareCascade(const DL_GroupPrecomputation<Element> &group, std::vector<BaseAndExponent<Element> > &eb, const Integer &exponent) const; |
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| 80 | |
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| 81 | Element m_base; |
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| 82 | unsigned int m_windowSize; |
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| 83 | Integer m_exponentBase; // what base to represent the exponent in |
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| 84 | std::vector<Element> m_bases; // precalculated bases |
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| 85 | }; |
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| 86 | |
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| 87 | NAMESPACE_END |
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| 88 | |
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| 89 | #ifdef CRYPTOPP_MANUALLY_INSTANTIATE_TEMPLATES |
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| 90 | #include "eprecomp.cpp" |
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| 91 | #endif |
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| 92 | |
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| 93 | #endif |
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