159 lines
5.2 KiB
C++
159 lines
5.2 KiB
C++
#ifndef CRYPTOPP_MODARITH_H
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#define CRYPTOPP_MODARITH_H
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// implementations are in integer.cpp
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#include "cryptlib.h"
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#include "misc.h"
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#include "integer.h"
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#include "algebra.h"
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NAMESPACE_BEGIN(CryptoPP)
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CRYPTOPP_DLL_TEMPLATE_CLASS AbstractGroup<Integer>;
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CRYPTOPP_DLL_TEMPLATE_CLASS AbstractRing<Integer>;
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CRYPTOPP_DLL_TEMPLATE_CLASS AbstractEuclideanDomain<Integer>;
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//! ring of congruence classes modulo n
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/*! \note this implementation represents each congruence class as the smallest non-negative integer in that class */
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class CRYPTOPP_DLL ModularArithmetic : public AbstractRing<Integer>
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{
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public:
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typedef int RandomizationParameter;
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typedef Integer Element;
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ModularArithmetic(const Integer &modulus = Integer::One())
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: m_modulus(modulus), m_result((word)0, modulus.reg.size()) {}
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ModularArithmetic(const ModularArithmetic &ma)
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: m_modulus(ma.m_modulus), m_result((word)0, m_modulus.reg.size()) {}
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ModularArithmetic(BufferedTransformation &bt); // construct from BER encoded parameters
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virtual ModularArithmetic * Clone() const {return new ModularArithmetic(*this);}
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void DEREncode(BufferedTransformation &bt) const;
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void DEREncodeElement(BufferedTransformation &out, const Element &a) const;
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void BERDecodeElement(BufferedTransformation &in, Element &a) const;
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const Integer& GetModulus() const {return m_modulus;}
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void SetModulus(const Integer &newModulus) {m_modulus = newModulus; m_result.reg.resize(m_modulus.reg.size());}
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virtual bool IsMontgomeryRepresentation() const {return false;}
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virtual Integer ConvertIn(const Integer &a) const
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{return a%m_modulus;}
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virtual Integer ConvertOut(const Integer &a) const
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{return a;}
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const Integer& Half(const Integer &a) const;
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bool Equal(const Integer &a, const Integer &b) const
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{return a==b;}
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const Integer& Identity() const
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{return Integer::Zero();}
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const Integer& Add(const Integer &a, const Integer &b) const;
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Integer& Accumulate(Integer &a, const Integer &b) const;
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const Integer& Inverse(const Integer &a) const;
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const Integer& Subtract(const Integer &a, const Integer &b) const;
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Integer& Reduce(Integer &a, const Integer &b) const;
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const Integer& Double(const Integer &a) const
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{return Add(a, a);}
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const Integer& MultiplicativeIdentity() const
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{return Integer::One();}
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const Integer& Multiply(const Integer &a, const Integer &b) const
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{return m_result1 = a*b%m_modulus;}
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const Integer& Square(const Integer &a) const
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{return m_result1 = a.Squared()%m_modulus;}
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bool IsUnit(const Integer &a) const
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{return Integer::Gcd(a, m_modulus).IsUnit();}
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const Integer& MultiplicativeInverse(const Integer &a) const
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{return m_result1 = a.InverseMod(m_modulus);}
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const Integer& Divide(const Integer &a, const Integer &b) const
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{return Multiply(a, MultiplicativeInverse(b));}
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Integer CascadeExponentiate(const Integer &x, const Integer &e1, const Integer &y, const Integer &e2) const;
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void SimultaneousExponentiate(Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const;
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unsigned int MaxElementBitLength() const
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{return (m_modulus-1).BitCount();}
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unsigned int MaxElementByteLength() const
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{return (m_modulus-1).ByteCount();}
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Element RandomElement( RandomNumberGenerator &rng , const RandomizationParameter &ignore_for_now = 0 ) const
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// left RandomizationParameter arg as ref in case RandomizationParameter becomes a more complicated struct
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{
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return Element( rng , Integer( (long) 0) , m_modulus - Integer( (long) 1 ) ) ;
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}
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bool operator==(const ModularArithmetic &rhs) const
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{return m_modulus == rhs.m_modulus;}
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static const RandomizationParameter DefaultRandomizationParameter ;
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protected:
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Integer m_modulus;
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mutable Integer m_result, m_result1;
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};
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// const ModularArithmetic::RandomizationParameter ModularArithmetic::DefaultRandomizationParameter = 0 ;
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//! do modular arithmetics in Montgomery representation for increased speed
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/*! \note the Montgomery representation represents each congruence class [a] as a*r%n, where r is a convenient power of 2 */
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class CRYPTOPP_DLL MontgomeryRepresentation : public ModularArithmetic
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{
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public:
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MontgomeryRepresentation(const Integer &modulus); // modulus must be odd
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virtual ModularArithmetic * Clone() const {return new MontgomeryRepresentation(*this);}
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bool IsMontgomeryRepresentation() const {return true;}
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Integer ConvertIn(const Integer &a) const
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{return (a<<(WORD_BITS*m_modulus.reg.size()))%m_modulus;}
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Integer ConvertOut(const Integer &a) const;
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const Integer& MultiplicativeIdentity() const
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{return m_result1 = Integer::Power2(WORD_BITS*m_modulus.reg.size())%m_modulus;}
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const Integer& Multiply(const Integer &a, const Integer &b) const;
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const Integer& Square(const Integer &a) const;
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const Integer& MultiplicativeInverse(const Integer &a) const;
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Integer CascadeExponentiate(const Integer &x, const Integer &e1, const Integer &y, const Integer &e2) const
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{return AbstractRing<Integer>::CascadeExponentiate(x, e1, y, e2);}
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void SimultaneousExponentiate(Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const
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{AbstractRing<Integer>::SimultaneousExponentiate(results, base, exponents, exponentsCount);}
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private:
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Integer m_u;
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mutable IntegerSecBlock m_workspace;
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};
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NAMESPACE_END
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#endif
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