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/*
* NIST elliptic curves over GF(p)
* (C) 2014 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_GFP_CURVE_NIST_H__
#define BOTAN_GFP_CURVE_NIST_H__
#include <botan/curve_gfp.h>
#include <memory>
namespace Botan {
class CurveGFp_NIST : public CurveGFp_Repr
{
public:
CurveGFp_NIST(size_t p_bits, const BigInt& a, const BigInt& b) :
m_a(a), m_b(b), m_p_words((p_bits + BOTAN_MP_WORD_BITS - 1) / BOTAN_MP_WORD_BITS)
{
}
size_t get_p_words() const override { return m_p_words; }
const BigInt& get_a() const override { return m_a; }
const BigInt& get_b() const override { return m_b; }
const BigInt& get_a_rep() const override { return m_a; }
const BigInt& get_b_rep() const override { return m_b; }
void to_curve_rep(BigInt& x, secure_vector<word>& ws) const override
{ redc(x, ws); }
void from_curve_rep(BigInt& x, secure_vector<word>& ws) const override
{ redc(x, ws); }
void curve_mul(BigInt& z, const BigInt& x, const BigInt& y,
secure_vector<word>& ws) const override;
void curve_sqr(BigInt& z, const BigInt& x,
secure_vector<word>& ws) const override;
private:
virtual void redc(BigInt& x, secure_vector<word>& ws) const = 0;
virtual size_t max_redc_subtractions() const = 0;
// Curve parameters
BigInt m_a, m_b;
size_t m_p_words; // cache of m_p.sig_words()
};
/**
* The NIST P-521 curve
*/
class CurveGFp_P521 : public CurveGFp_NIST
{
public:
CurveGFp_P521(const BigInt& a, const BigInt& b) : CurveGFp_NIST(521, a, b) {}
static const BigInt& prime();
const BigInt& get_p() const override { return CurveGFp_P521::prime(); }
private:
void redc(BigInt& x, secure_vector<word>& ws) const override;
size_t max_redc_subtractions() const override { return 1; }
};
}
#endif
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