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/*
* Modular Exponentiation
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_DEFAULT_MODEXP_H__
#define BOTAN_DEFAULT_MODEXP_H__
#include <botan/pow_mod.h>
#include <botan/reducer.h>
#include <vector>
namespace Botan {
/**
* Fixed Window Exponentiator
*/
class Fixed_Window_Exponentiator : public Modular_Exponentiator
{
public:
void set_exponent(const BigInt&);
void set_base(const BigInt&);
BigInt execute() const;
Modular_Exponentiator* copy() const
{ return new Fixed_Window_Exponentiator(*this); }
Fixed_Window_Exponentiator(const BigInt&, Power_Mod::Usage_Hints);
private:
Modular_Reducer reducer;
BigInt exp;
size_t window_bits;
std::vector<BigInt> g;
Power_Mod::Usage_Hints hints;
};
/**
* Montgomery Exponentiator
*/
class Montgomery_Exponentiator : public Modular_Exponentiator
{
public:
void set_exponent(const BigInt&);
void set_base(const BigInt&);
BigInt execute() const;
Modular_Exponentiator* copy() const
{ return new Montgomery_Exponentiator(*this); }
Montgomery_Exponentiator(const BigInt&, Power_Mod::Usage_Hints);
private:
BigInt exp, modulus;
BigInt R2, R_mod;
std::vector<BigInt> g;
word mod_prime;
size_t mod_words, exp_bits, window_bits;
Power_Mod::Usage_Hints hints;
};
}
#endif
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