Crypto++: eprecomp.h Source File

00001 #ifndef CRYPTOPP_EPRECOMP_H 00002 #define CRYPTOPP_EPRECOMP_H 00003 00004 #include "integer.h" 00005 #include "algebra.h" 00006 #include <vector> 00007 00008 NAMESPACE_BEGIN(CryptoPP) 00009 00010 template <class T> 00011 class DL_GroupPrecomputation 00012 { 00013 public: 00014 typedef T Element; 00015 00016 virtual bool NeedConversions() const {return false;} 00017 virtual Element ConvertIn(const Element &v) const {return v;} 00018 virtual Element ConvertOut(const Element &v) const {return v;} 00019 virtual const AbstractGroup<Element> & GetGroup() const =0; 00020 virtual Element BERDecodeElement(BufferedTransformation &bt) const =0; 00021 virtual void DEREncodeElement(BufferedTransformation &bt, const Element &P) const =0; 00022 }; 00023 00024 template <class T> 00025 class DL_FixedBasePrecomputation 00026 { 00027 public: 00028 typedef T Element; 00029 00030 virtual bool IsInitialized() const =0; 00031 virtual void SetBase(const DL_GroupPrecomputation<Element> &group, const Element &base) =0; 00032 virtual const Element & GetBase(const DL_GroupPrecomputation<Element> &group) const =0; 00033 virtual void Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage) =0; 00034 virtual void Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) =0; 00035 virtual void Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) const =0; 00036 virtual Element Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const =0; 00037 virtual Element CascadeExponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent, const DL_FixedBasePrecomputation<Element> &pc2, const Integer &exponent2) const =0; 00038 }; 00039 00040 template <class T> 00041 class DL_FixedBasePrecomputationImpl : public DL_FixedBasePrecomputation<T> 00042 { 00043 public: 00044 typedef T Element; 00045 00046 // DL_FixedBasePrecomputation 00047 bool IsInitialized() const 00048 {return !m_bases.empty();} 00049 void SetBase(const DL_GroupPrecomputation<Element> &group, const Element &base); 00050 const Element & GetBase(const DL_GroupPrecomputation<Element> &group) const 00051 {return group.NeedConversions() ? m_base : m_bases[0];} 00052 void Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage); 00053 void Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation); 00054 void Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) const; 00055 Element Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const; 00056 Element CascadeExponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent, const DL_FixedBasePrecomputation<Element> &pc2, const Integer &exponent2) const; 00057 00058 private: 00059 void PrepareCascade(const DL_GroupPrecomputation<Element> &group, std::vector<BaseAndExponent<Element> > &eb, const Integer &exponent) const; 00060 00061 Element m_base; 00062 unsigned int m_windowSize; 00063 Integer m_exponentBase; // what base to represent the exponent in 00064 std::vector<Element> m_bases; // precalculated bases 00065 }; 00066 00067 NAMESPACE_END 00068 00069 #endif