00001 #ifndef CRYPTOPP_MODARITH_H
00002 #define CRYPTOPP_MODARITH_H
00003
00004
00005
00006 #include "cryptlib.h"
00007 #include "misc.h"
00008 #include "integer.h"
00009 #include "algebra.h"
00010
00011 NAMESPACE_BEGIN(CryptoPP)
00012
00013 CRYPTOPP_DLL_TEMPLATE_CLASS AbstractGroup<Integer>;
00014 CRYPTOPP_DLL_TEMPLATE_CLASS AbstractRing<Integer>;
00015 CRYPTOPP_DLL_TEMPLATE_CLASS AbstractEuclideanDomain<Integer>;
00016
00017
00018
00019 class CRYPTOPP_DLL ModularArithmetic : public AbstractRing<Integer>
00020 {
00021 public:
00022
00023 typedef int RandomizationParameter;
00024 typedef Integer Element;
00025
00026 ModularArithmetic(const Integer &modulus = Integer::One())
00027 : m_modulus(modulus), m_result((word)0, modulus.reg.size()) {}
00028
00029 ModularArithmetic(const ModularArithmetic &ma)
00030 : m_modulus(ma.m_modulus), m_result((word)0, m_modulus.reg.size()) {}
00031
00032 ModularArithmetic(BufferedTransformation &bt);
00033
00034 virtual ModularArithmetic * Clone() const {return new ModularArithmetic(*this);}
00035
00036 void DEREncode(BufferedTransformation &bt) const;
00037
00038 void DEREncodeElement(BufferedTransformation &out, const Element &a) const;
00039 void BERDecodeElement(BufferedTransformation &in, Element &a) const;
00040
00041 const Integer& GetModulus() const {return m_modulus;}
00042 void SetModulus(const Integer &newModulus) {m_modulus = newModulus; m_result.reg.resize(m_modulus.reg.size());}
00043
00044 virtual bool IsMontgomeryRepresentation() const {return false;}
00045
00046 virtual Integer ConvertIn(const Integer &a) const
00047 {return a%m_modulus;}
00048
00049 virtual Integer ConvertOut(const Integer &a) const
00050 {return a;}
00051
00052 const Integer& Half(const Integer &a) const;
00053
00054 bool Equal(const Integer &a, const Integer &b) const
00055 {return a==b;}
00056
00057 const Integer& Identity() const
00058 {return Integer::Zero();}
00059
00060 const Integer& Add(const Integer &a, const Integer &b) const;
00061
00062 Integer& Accumulate(Integer &a, const Integer &b) const;
00063
00064 const Integer& Inverse(const Integer &a) const;
00065
00066 const Integer& Subtract(const Integer &a, const Integer &b) const;
00067
00068 Integer& Reduce(Integer &a, const Integer &b) const;
00069
00070 const Integer& Double(const Integer &a) const
00071 {return Add(a, a);}
00072
00073 const Integer& MultiplicativeIdentity() const
00074 {return Integer::One();}
00075
00076 const Integer& Multiply(const Integer &a, const Integer &b) const
00077 {return m_result1 = a*b%m_modulus;}
00078
00079 const Integer& Square(const Integer &a) const
00080 {return m_result1 = a.Squared()%m_modulus;}
00081
00082 bool IsUnit(const Integer &a) const
00083 {return Integer::Gcd(a, m_modulus).IsUnit();}
00084
00085 const Integer& MultiplicativeInverse(const Integer &a) const
00086 {return m_result1 = a.InverseMod(m_modulus);}
00087
00088 const Integer& Divide(const Integer &a, const Integer &b) const
00089 {return Multiply(a, MultiplicativeInverse(b));}
00090
00091 Integer CascadeExponentiate(const Integer &x, const Integer &e1, const Integer &y, const Integer &e2) const;
00092
00093 void SimultaneousExponentiate(Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const;
00094
00095 unsigned int MaxElementBitLength() const
00096 {return (m_modulus-1).BitCount();}
00097
00098 unsigned int MaxElementByteLength() const
00099 {return (m_modulus-1).ByteCount();}
00100
00101 Element RandomElement( RandomNumberGenerator &rng , const RandomizationParameter &ignore_for_now = 0 ) const
00102
00103 {
00104 return Element( rng , Integer( (long) 0) , m_modulus - Integer( (long) 1 ) ) ;
00105 }
00106
00107 bool operator==(const ModularArithmetic &rhs) const
00108 {return m_modulus == rhs.m_modulus;}
00109
00110 static const RandomizationParameter DefaultRandomizationParameter ;
00111
00112 protected:
00113 Integer m_modulus;
00114 mutable Integer m_result, m_result1;
00115
00116 };
00117
00118
00119
00120
00121
00122 class CRYPTOPP_DLL MontgomeryRepresentation : public ModularArithmetic
00123 {
00124 public:
00125 MontgomeryRepresentation(const Integer &modulus);
00126
00127 virtual ModularArithmetic * Clone() const {return new MontgomeryRepresentation(*this);}
00128
00129 bool IsMontgomeryRepresentation() const {return true;}
00130
00131 Integer ConvertIn(const Integer &a) const
00132 {return (a<<(WORD_BITS*m_modulus.reg.size()))%m_modulus;}
00133
00134 Integer ConvertOut(const Integer &a) const;
00135
00136 const Integer& MultiplicativeIdentity() const
00137 {return m_result1 = Integer::Power2(WORD_BITS*m_modulus.reg.size())%m_modulus;}
00138
00139 const Integer& Multiply(const Integer &a, const Integer &b) const;
00140
00141 const Integer& Square(const Integer &a) const;
00142
00143 const Integer& MultiplicativeInverse(const Integer &a) const;
00144
00145 Integer CascadeExponentiate(const Integer &x, const Integer &e1, const Integer &y, const Integer &e2) const
00146 {return AbstractRing<Integer>::CascadeExponentiate(x, e1, y, e2);}
00147
00148 void SimultaneousExponentiate(Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const
00149 {AbstractRing<Integer>::SimultaneousExponentiate(results, base, exponents, exponentsCount);}
00150
00151 private:
00152 Integer m_u;
00153 mutable SecAlignedWordBlock m_workspace;
00154 };
00155
00156 NAMESPACE_END
00157
00158 #endif