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ecp.h

00001 #ifndef CRYPTOPP_ECP_H 00002 #define CRYPTOPP_ECP_H 00003 00004 #include "modarith.h" 00005 #include "eprecomp.h" 00006 #include "smartptr.h" 00007 #include "pubkey.h" 00008 00009 NAMESPACE_BEGIN(CryptoPP) 00010 00011 //! Elliptical Curve Point 00012 struct ECPPoint 00013 { 00014 ECPPoint() : identity(true) {} 00015 ECPPoint(const Integer &x, const Integer &y) 00016 : identity(false), x(x), y(y) {} 00017 00018 bool operator==(const ECPPoint &t) const 00019 {return (identity && t.identity) || (!identity && !t.identity && x==t.x && y==t.y);} 00020 bool operator< (const ECPPoint &t) const 00021 {return identity ? !t.identity : (!t.identity && (x<t.x || (x==t.x && y<t.y)));} 00022 00023 bool identity; 00024 Integer x, y; 00025 }; 00026 00027 //! Elliptic Curve over GF(p), where p is prime 00028 class ECP : public AbstractGroup<ECPPoint> 00029 { 00030 public: 00031 typedef ModularArithmetic Field; 00032 typedef Integer FieldElement; 00033 typedef ECPPoint Point; 00034 00035 ECP() {} 00036 ECP(const ECP &ecp, bool convertToMontgomeryRepresentation = false); 00037 ECP(const Integer &modulus, const FieldElement &a, const FieldElement &b) 00038 : m_fieldPtr(new Field(modulus)), m_a(a.IsNegative() ? modulus+a : a), m_b(b) {} 00039 // construct from BER encoded parameters 00040 // this constructor will decode and extract the the fields fieldID and curve of the sequence ECParameters 00041 ECP(BufferedTransformation &bt); 00042 00043 // encode the fields fieldID and curve of the sequence ECParameters 00044 void DEREncode(BufferedTransformation &bt) const; 00045 00046 bool Equal(const Point &P, const Point &Q) const; 00047 const Point& Identity() const; 00048 const Point& Inverse(const Point &P) const; 00049 bool InversionIsFast() const {return true;} 00050 const Point& Add(const Point &P, const Point &Q) const; 00051 const Point& Double(const Point &P) const; 00052 Point ScalarMultiply(const Point &P, const Integer &k) const; 00053 Point CascadeScalarMultiply(const Point &P, const Integer &k1, const Point &Q, const Integer &k2) const; 00054 void SimultaneousMultiply(Point *results, const Point &base, const Integer *exponents, unsigned int exponentsCount) const; 00055 00056 Point Multiply(const Integer &k, const Point &P) const 00057 {return ScalarMultiply(P, k);} 00058 Point CascadeMultiply(const Integer &k1, const Point &P, const Integer &k2, const Point &Q) const 00059 {return CascadeScalarMultiply(P, k1, Q, k2);} 00060 00061 bool ValidateParameters(RandomNumberGenerator &rng, unsigned int level=3) const; 00062 bool VerifyPoint(const Point &P) const; 00063 00064 unsigned int EncodedPointSize(bool compressed = false) const 00065 {return 1 + (compressed?1:2)*GetField().MaxElementByteLength();} 00066 // returns false if point is compressed and not valid (doesn't check if uncompressed) 00067 bool DecodePoint(Point &P, BufferedTransformation &bt, unsigned int len) const; 00068 bool DecodePoint(Point &P, const byte *encodedPoint, unsigned int len) const; 00069 void EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const; 00070 void EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const; 00071 00072 Point BERDecodePoint(BufferedTransformation &bt) const; 00073 void DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const; 00074 00075 Integer FieldSize() const {return GetField().GetModulus();} 00076 const Field & GetField() const {return *m_fieldPtr;} 00077 const FieldElement & GetA() const {return m_a;} 00078 const FieldElement & GetB() const {return m_b;} 00079 00080 private: 00081 clonable_ptr<Field> m_fieldPtr; 00082 FieldElement m_a, m_b; 00083 mutable Point m_R; 00084 }; 00085 00086 template <class T> class EcPrecomputation; 00087 00088 //! . 00089 template<> class EcPrecomputation<ECP> : public DL_GroupPrecomputation<ECP::Point> 00090 { 00091 public: 00092 typedef ECP EllipticCurve; 00093 00094 // DL_GroupPrecomputation 00095 bool NeedConversions() const {return true;} 00096 Element ConvertIn(const Element &P) const 00097 {return P.identity ? P : ECP::Point(m_ec->GetField().ConvertIn(P.x), m_ec->GetField().ConvertIn(P.y));}; 00098 Element ConvertOut(const Element &P) const 00099 {return P.identity ? P : ECP::Point(m_ec->GetField().ConvertOut(P.x), m_ec->GetField().ConvertOut(P.y));} 00100 const AbstractGroup<Element> & GetGroup() const {return *m_ec;} 00101 Element BERDecodeElement(BufferedTransformation &bt) const {return m_ec->BERDecodePoint(bt);} 00102 void DEREncodeElement(BufferedTransformation &bt, const Element &v) const {m_ec->DEREncodePoint(bt, v, false);} 00103 00104 // non-inherited 00105 void SetCurve(const ECP &ec); 00106 const ECP & GetCurve() const {return *m_ecOriginal;} 00107 00108 private: 00109 value_ptr<ECP> m_ec, m_ecOriginal; 00110 }; 00111 00112 NAMESPACE_END 00113 00114 #endif

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