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#ifndef CRYPTOPP_EC2N_H
#define CRYPTOPP_EC2N_H
#include "gf2n.h"
#include "eprecomp.h"
#include "smartptr.h"
#include "pubkey.h"
NAMESPACE_BEGIN(CryptoPP)
//! Elliptic Curve Point
struct CRYPTOPP_DLL EC2NPoint{ EC2NPoint() : identity(true) {} EC2NPoint(const PolynomialMod2 &x, const PolynomialMod2 &y) : identity(false), x(x), y(y) {}
bool operator==(const EC2NPoint &t) const {return (identity && t.identity) || (!identity && !t.identity && x==t.x && y==t.y);} bool operator< (const EC2NPoint &t) const {return identity ? !t.identity : (!t.identity && (x<t.x || (x==t.x && y<t.y)));}
bool identity; PolynomialMod2 x, y;};
CRYPTOPP_DLL_TEMPLATE_CLASS AbstractGroup<EC2NPoint>;
//! Elliptic Curve over GF(2^n)
class CRYPTOPP_DLL EC2N : public AbstractGroup<EC2NPoint>{public: typedef GF2NP Field; typedef Field::Element FieldElement; typedef EC2NPoint Point;
EC2N() {} EC2N(const Field &field, const Field::Element &a, const Field::Element &b) : m_field(field), m_a(a), m_b(b) {} // construct from BER encoded parameters
// this constructor will decode and extract the the fields fieldID and curve of the sequence ECParameters
EC2N(BufferedTransformation &bt);
// encode the fields fieldID and curve of the sequence ECParameters
void DEREncode(BufferedTransformation &bt) const;
bool Equal(const Point &P, const Point &Q) const; const Point& Identity() const; const Point& Inverse(const Point &P) const; bool InversionIsFast() const {return true;} const Point& Add(const Point &P, const Point &Q) const; const Point& Double(const Point &P) const;
Point Multiply(const Integer &k, const Point &P) const {return ScalarMultiply(P, k);} Point CascadeMultiply(const Integer &k1, const Point &P, const Integer &k2, const Point &Q) const {return CascadeScalarMultiply(P, k1, Q, k2);}
bool ValidateParameters(RandomNumberGenerator &rng, unsigned int level=3) const; bool VerifyPoint(const Point &P) const;
unsigned int EncodedPointSize(bool compressed = false) const {return 1 + (compressed?1:2)*m_field->MaxElementByteLength();} // returns false if point is compressed and not valid (doesn't check if uncompressed)
bool DecodePoint(Point &P, BufferedTransformation &bt, size_t len) const; bool DecodePoint(Point &P, const byte *encodedPoint, size_t len) const; void EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const; void EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
Point BERDecodePoint(BufferedTransformation &bt) const; void DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
Integer FieldSize() const {return Integer::Power2(m_field->MaxElementBitLength());} const Field & GetField() const {return *m_field;} const FieldElement & GetA() const {return m_a;} const FieldElement & GetB() const {return m_b;}
bool operator==(const EC2N &rhs) const {return GetField() == rhs.GetField() && m_a == rhs.m_a && m_b == rhs.m_b;}
private: clonable_ptr<Field> m_field; FieldElement m_a, m_b; mutable Point m_R;};
CRYPTOPP_DLL_TEMPLATE_CLASS DL_FixedBasePrecomputationImpl<EC2N::Point>;CRYPTOPP_DLL_TEMPLATE_CLASS DL_GroupPrecomputation<EC2N::Point>;
template <class T> class EcPrecomputation;
//! EC2N precomputation
template<> class EcPrecomputation<EC2N> : public DL_GroupPrecomputation<EC2N::Point>{public: typedef EC2N EllipticCurve;
// DL_GroupPrecomputation
const AbstractGroup<Element> & GetGroup() const {return m_ec;} Element BERDecodeElement(BufferedTransformation &bt) const {return m_ec.BERDecodePoint(bt);} void DEREncodeElement(BufferedTransformation &bt, const Element &v) const {m_ec.DEREncodePoint(bt, v, false);}
// non-inherited
void SetCurve(const EC2N &ec) {m_ec = ec;} const EC2N & GetCurve() const {return m_ec;}
private: EC2N m_ec;};
NAMESPACE_END
#endif
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