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
00014 class
ModularArithmetic : public
AbstractRing<
Integer>
00015 {
00016
public:
00017
00018
typedef int RandomizationParameter;
00019
typedef Integer
Element;
00020
00021
ModularArithmetic(
const Integer &modulus = Integer::One())
00022 : modulus(modulus), result((word)0, modulus.reg.size()) {}
00023
00024
ModularArithmetic(
const ModularArithmetic &ma)
00025 : modulus(ma.
modulus), result((word)0, modulus.reg.size()) {}
00026
00027
ModularArithmetic(
BufferedTransformation &bt);
00028
00029
virtual ModularArithmetic * Clone()
const {
return new ModularArithmetic(*
this);}
00030
00031
void DEREncode(
BufferedTransformation &bt)
const;
00032
00033
void DEREncodeElement(
BufferedTransformation &out,
const Element &a)
const;
00034
void BERDecodeElement(
BufferedTransformation &in, Element &a)
const;
00035
00036
const Integer& GetModulus()
const {
return modulus;}
00037
void SetModulus(
const Integer &newModulus) {modulus = newModulus; result.
reg.
resize(modulus.reg.size());}
00038
00039
virtual bool IsMontgomeryRepresentation()
const {
return false;}
00040
00041
virtual Integer ConvertIn(
const Integer &a)
const
00042
{
return a%modulus;}
00043
00044
virtual Integer ConvertOut(
const Integer &a)
const
00045
{
return a;}
00046
00047
const Integer& Half(
const Integer &a)
const;
00048
00049
bool Equal(
const Integer &a,
const Integer &b)
const
00050
{
return a==b;}
00051
00052
const Integer& Identity()
const
00053
{
return Integer::Zero();}
00054
00055
const Integer& Add(
const Integer &a,
const Integer &b)
const;
00056
00057 Integer& Accumulate(Integer &a,
const Integer &b)
const;
00058
00059
const Integer& Inverse(
const Integer &a)
const;
00060
00061
const Integer& Subtract(
const Integer &a,
const Integer &b)
const;
00062
00063 Integer& Reduce(Integer &a,
const Integer &b)
const;
00064
00065
const Integer& Double(
const Integer &a)
const
00066
{
return Add(a, a);}
00067
00068
const Integer& MultiplicativeIdentity()
const
00069
{
return Integer::One();}
00070
00071
const Integer& Multiply(
const Integer &a,
const Integer &b)
const
00072
{
return result1 = a*b%modulus;}
00073
00074
const Integer&
Square(
const Integer &a)
const
00075
{
return result1 = a.Squared()%modulus;}
00076
00077
bool IsUnit(
const Integer &a)
const
00078
{
return Integer::Gcd(a, modulus).
IsUnit();}
00079
00080
const Integer& MultiplicativeInverse(
const Integer &a)
const
00081
{
return result1 = a.InverseMod(modulus);}
00082
00083
const Integer& Divide(
const Integer &a,
const Integer &b)
const
00084
{
return Multiply(a, MultiplicativeInverse(b));}
00085
00086 Integer CascadeExponentiate(
const Integer &x,
const Integer &e1,
const Integer &y,
const Integer &e2)
const;
00087
00088
void SimultaneousExponentiate(Element *results,
const Element &base,
const Integer *exponents,
unsigned int exponentsCount)
const;
00089
00090
unsigned int MaxElementBitLength()
const
00091
{
return (modulus-1).BitCount();}
00092
00093
unsigned int MaxElementByteLength()
const
00094
{
return (modulus-1).ByteCount();}
00095
00096 Element RandomElement(
RandomNumberGenerator &rng ,
const RandomizationParameter &ignore_for_now = 0 )
const
00097
00098 {
00099
return Element( rng , Integer( (
long) 0) , modulus - Integer( (
long) 1 ) ) ;
00100 }
00101
00102
static const RandomizationParameter DefaultRandomizationParameter ;
00103
00104
protected:
00105 Integer modulus;
00106
mutable Integer result, result1;
00107
00108 };
00109
00110
00111
00112
00113 class MontgomeryRepresentation :
public ModularArithmetic
00114 {
00115
public:
00116
MontgomeryRepresentation(
const Integer &modulus);
00117
00118
virtual ModularArithmetic * Clone()
const {
return new MontgomeryRepresentation(*
this);}
00119
00120
bool IsMontgomeryRepresentation()
const {
return true;}
00121
00122
Integer ConvertIn(
const Integer &a)
const
00123
{
return (a<<(WORD_BITS*modulus.
reg.
size()))%modulus;}
00124
00125
Integer ConvertOut(
const Integer &a)
const;
00126
00127
const Integer& MultiplicativeIdentity()
const
00128
{
return result1 = Integer::Power2(WORD_BITS*modulus.
reg.
size())%modulus;}
00129
00130
const Integer& Multiply(
const Integer &a,
const Integer &b)
const;
00131
00132
const Integer&
Square(
const Integer &a)
const;
00133
00134
const Integer& MultiplicativeInverse(
const Integer &a)
const;
00135
00136
Integer CascadeExponentiate(
const Integer &x,
const Integer &e1,
const Integer &y,
const Integer &e2)
const
00137
{
return AbstractRing<Integer>::CascadeExponentiate(x, e1, y, e2);}
00138
00139
void SimultaneousExponentiate(Element *results,
const Element &base,
const Integer *exponents,
unsigned int exponentsCount)
const
00140
{
AbstractRing<Integer>::SimultaneousExponentiate(results, base, exponents, exponentsCount);}
00141
00142
private:
00143
Integer u;
00144
mutable SecAlignedWordBlock workspace;
00145 };
00146
00147 NAMESPACE_END
00148
00149
#endif