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_FixedBasePrecomputationImpl() : m_windowSize(0) {}
00047 
00048         // DL_FixedBasePrecomputation
00049         bool IsInitialized() const
00050                 {return !m_bases.empty();}
00051         void SetBase(const DL_GroupPrecomputation<Element> &group, const Element &base);
00052         const Element & GetBase(const DL_GroupPrecomputation<Element> &group) const
00053                 {return group.NeedConversions() ? m_base : m_bases[0];}
00054         void Precompute(const DL_GroupPrecomputation<Element> &group, unsigned int maxExpBits, unsigned int storage);
00055         void Load(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation);
00056         void Save(const DL_GroupPrecomputation<Element> &group, BufferedTransformation &storedPrecomputation) const;
00057         Element Exponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent) const;
00058         Element CascadeExponentiate(const DL_GroupPrecomputation<Element> &group, const Integer &exponent, const DL_FixedBasePrecomputation<Element> &pc2, const Integer &exponent2) const;
00059 
00060 private:
00061         void PrepareCascade(const DL_GroupPrecomputation<Element> &group, std::vector<BaseAndExponent<Element> > &eb, const Integer &exponent) const;
00062 
00063         Element m_base;
00064         unsigned int m_windowSize;
00065         Integer m_exponentBase;                 // what base to represent the exponent in
00066         std::vector<Element> m_bases;   // precalculated bases
00067 };
00068 
00069 NAMESPACE_END
00070 
00071 #ifdef CRYPTOPP_MANUALLY_INSTANTIATE_TEMPLATES
00072 #include "eprecomp.cpp"
00073 #endif
00074 
00075 #endif