00001 #ifndef CRYPTOPP_EC2N_H
00002 #define CRYPTOPP_EC2N_H
00003
00004 #include "gf2n.h"
00005 #include "eprecomp.h"
00006 #include "smartptr.h"
00007 #include "pubkey.h"
00008
00009 NAMESPACE_BEGIN(CryptoPP)
00010
00011
00012 struct EC2NPoint
00013 {
00014 EC2NPoint() : identity(true) {}
00015 EC2NPoint(const PolynomialMod2 &x, const PolynomialMod2 &y)
00016 : identity(false), x(x), y(y) {}
00017
00018 bool operator==(const EC2NPoint &t) const
00019 {return (identity && t.identity) || (!identity && !t.identity && x==t.x && y==t.y);}
00020 bool operator< (const EC2NPoint &t) const
00021 {return identity ? !t.identity : (!t.identity && (x<t.x || (x==t.x && y<t.y)));}
00022
00023 bool identity;
00024 PolynomialMod2 x, y;
00025 };
00026
00027
00028 class EC2N : public AbstractGroup<EC2NPoint>
00029 {
00030 public:
00031 typedef GF2NP Field;
00032 typedef Field::Element FieldElement;
00033 typedef EC2NPoint Point;
00034
00035 EC2N() {}
00036 EC2N(const Field &field, const Field::Element &a, const Field::Element &b)
00037 : m_field(field), m_a(a), m_b(b) {}
00038
00039
00040 EC2N(BufferedTransformation &bt);
00041
00042
00043 void DEREncode(BufferedTransformation &bt) const;
00044
00045 bool Equal(const Point &P, const Point &Q) const;
00046 const Point& Identity() const;
00047 const Point& Inverse(const Point &P) const;
00048 bool InversionIsFast() const {return true;}
00049 const Point& Add(const Point &P, const Point &Q) const;
00050 const Point& Double(const Point &P) const;
00051
00052 Point Multiply(const Integer &k, const Point &P) const
00053 {return ScalarMultiply(P, k);}
00054 Point CascadeMultiply(const Integer &k1, const Point &P, const Integer &k2, const Point &Q) const
00055 {return CascadeScalarMultiply(P, k1, Q, k2);}
00056
00057 bool ValidateParameters(RandomNumberGenerator &rng, unsigned int level=3) const;
00058 bool VerifyPoint(const Point &P) const;
00059
00060 unsigned int EncodedPointSize(bool compressed = false) const
00061 {return 1 + (compressed?1:2)*m_field->MaxElementByteLength();}
00062
00063 bool DecodePoint(Point &P, BufferedTransformation &bt, unsigned int len) const;
00064 bool DecodePoint(Point &P, const byte *encodedPoint, unsigned int len) const;
00065 void EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const;
00066 void EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
00067
00068 Point BERDecodePoint(BufferedTransformation &bt) const;
00069 void DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
00070
00071 Integer FieldSize() const {return Integer::Power2(m_field->MaxElementBitLength());}
00072 const Field & GetField() const {return *m_field;}
00073 const FieldElement & GetA() const {return m_a;}
00074 const FieldElement & GetB() const {return m_b;}
00075
00076 private:
00077 clonable_ptr<Field> m_field;
00078 FieldElement m_a, m_b;
00079 mutable Point m_R;
00080 };
00081
00082 template <class T> class EcPrecomputation;
00083
00084
00085 template<> class EcPrecomputation<EC2N> : public DL_GroupPrecomputation<EC2N::Point>
00086 {
00087 public:
00088 typedef EC2N EllipticCurve;
00089
00090
00091 const AbstractGroup<Element> & GetGroup() const {return m_ec;}
00092 Element BERDecodeElement(BufferedTransformation &bt) const {return m_ec.BERDecodePoint(bt);}
00093 void DEREncodeElement(BufferedTransformation &bt, const Element &v) const {m_ec.DEREncodePoint(bt, v, false);}
00094
00095
00096 void SetCurve(const EC2N &ec) {m_ec = ec;}
00097 const EC2N & GetCurve() const {return m_ec;}
00098
00099 private:
00100 EC2N m_ec;
00101 };
00102
00103 NAMESPACE_END
00104
00105 #endif