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/*
* Elliptic curves over GF(p)
*
* (C) 2007 Martin Doering, Christoph Ludwig, Falko Strenzke
* 2010-2011,2012,2014 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_GFP_CURVE_H_
#define BOTAN_GFP_CURVE_H_
#include <botan/bigint.h>
#include <memory>
namespace Botan {
class BOTAN_UNSTABLE_API CurveGFp_Repr
{
public:
virtual ~CurveGFp_Repr() = default;
virtual const BigInt& get_p() const = 0;
virtual const BigInt& get_a() const = 0;
virtual const BigInt& get_b() const = 0;
virtual size_t get_p_words() const = 0;
/*
* Returns to_curve_rep(get_a())
*/
virtual const BigInt& get_a_rep() const = 0;
/*
* Returns to_curve_rep(get_b())
*/
virtual const BigInt& get_b_rep() const = 0;
virtual void to_curve_rep(BigInt& x, secure_vector<word>& ws) const = 0;
virtual void from_curve_rep(BigInt& x, secure_vector<word>& ws) const = 0;
virtual void curve_mul(BigInt& z, const BigInt& x, const BigInt& y,
secure_vector<word>& ws) const = 0;
virtual void curve_sqr(BigInt& z, const BigInt& x,
secure_vector<word>& ws) const = 0;
};
/**
* This class represents an elliptic curve over GF(p)
*/
class BOTAN_PUBLIC_API(2,0) CurveGFp final
{
public:
/**
* Create an uninitialized CurveGFp
*/
CurveGFp() = default;
/**
* Construct the elliptic curve E: y^2 = x^3 + ax + b over GF(p)
* @param p prime number of the field
* @param a first coefficient
* @param b second coefficient
*/
CurveGFp(const BigInt& p, const BigInt& a, const BigInt& b) :
m_repr(choose_repr(p, a, b))
{
}
CurveGFp(const CurveGFp&) = default;
CurveGFp& operator=(const CurveGFp&) = default;
/**
* @return curve coefficient a
*/
const BigInt& get_a() const { return m_repr->get_a(); }
/**
* @return curve coefficient b
*/
const BigInt& get_b() const { return m_repr->get_b(); }
/**
* Get prime modulus of the field of the curve
* @return prime modulus of the field of the curve
*/
const BigInt& get_p() const { return m_repr->get_p(); }
const BigInt& get_a_rep() const { return m_repr->get_a_rep(); }
const BigInt& get_b_rep() const { return m_repr->get_b_rep(); }
void to_rep(BigInt& x, secure_vector<word>& ws) const
{
m_repr->to_curve_rep(x, ws);
}
void from_rep(BigInt& x, secure_vector<word>& ws) const
{
m_repr->from_curve_rep(x, ws);
}
BigInt from_rep(const BigInt& x, secure_vector<word>& ws) const
{
BigInt xt(x);
m_repr->from_curve_rep(xt, ws);
return xt;
}
// TODO: from_rep taking && ref
void mul(BigInt& z, const BigInt& x, const BigInt& y, secure_vector<word>& ws) const
{
m_repr->curve_mul(z, x, y, ws);
}
BigInt mul(const BigInt& x, const BigInt& y, secure_vector<word>& ws) const
{
BigInt z;
m_repr->curve_mul(z, x, y, ws);
return z;
}
void sqr(BigInt& z, const BigInt& x, secure_vector<word>& ws) const
{
m_repr->curve_sqr(z, x, ws);
}
BigInt sqr(const BigInt& x, secure_vector<word>& ws) const
{
BigInt z;
m_repr->curve_sqr(z, x, ws);
return z;
}
void swap(CurveGFp& other)
{
std::swap(m_repr, other.m_repr);
}
private:
static std::shared_ptr<CurveGFp_Repr>
choose_repr(const BigInt& p, const BigInt& a, const BigInt& b);
std::shared_ptr<CurveGFp_Repr> m_repr;
};
/**
* Equality operator
* @param lhs a curve
* @param rhs a curve
* @return true iff lhs is the same as rhs
*/
inline bool operator==(const CurveGFp& lhs, const CurveGFp& rhs)
{
return (lhs.get_p() == rhs.get_p()) &&
(lhs.get_a() == rhs.get_a()) &&
(lhs.get_b() == rhs.get_b());
}
inline bool operator!=(const CurveGFp& lhs, const CurveGFp& rhs)
{
return !(lhs == rhs);
}
}
namespace std {
template<> inline
void swap<Botan::CurveGFp>(Botan::CurveGFp& curve1,
Botan::CurveGFp& curve2) BOTAN_NOEXCEPT
{
curve1.swap(curve2);
}
} // namespace std
#endif
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