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ec2n.h

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 //! Elliptic Curve Point 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 //! Elliptic Curve over GF(2^n) 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 // construct from BER encoded parameters 00039 // this constructor will decode and extract the the fields fieldID and curve of the sequence ECParameters 00040 EC2N(BufferedTransformation &bt); 00041 00042 // encode the fields fieldID and curve of the sequence ECParameters 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 // returns false if point is compressed and not valid (doesn't check if uncompressed) 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 // DL_GroupPrecomputation 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 // non-inherited 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

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