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/*
* Modular Exponentiation
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#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&) override;
void set_base(const BigInt&) override;
BigInt execute() const override;
Modular_Exponentiator* copy() const override
{ 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&) override;
void set_base(const BigInt&) override;
BigInt execute() const override;
Modular_Exponentiator* copy() const override
{ return new Montgomery_Exponentiator(*this); }
Montgomery_Exponentiator(const BigInt&, Power_Mod::Usage_Hints);
private:
BigInt m_exp, m_modulus, m_R_mod, m_R2_mod;
word m_mod_prime;
size_t m_mod_words, m_exp_bits, m_window_bits;
Power_Mod::Usage_Hints m_hints;
std::vector<BigInt> m_g;
};
}
#endif
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