137 lines
4.5 KiB
C++
137 lines
4.5 KiB
C++
// ec2n.h - originally written and placed in the public domain by Wei Dai
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/// \file ec2n.h
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/// \brief Classes for Elliptic Curves over binary fields
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#ifndef CRYPTOPP_EC2N_H
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#define CRYPTOPP_EC2N_H
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#include "cryptlib.h"
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#include "gf2n.h"
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#include "integer.h"
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#include "algebra.h"
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#include "ecpoint.h"
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#include "eprecomp.h"
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#include "smartptr.h"
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#include "pubkey.h"
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#if CRYPTOPP_MSC_VERSION
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# pragma warning(push)
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# pragma warning(disable: 4231 4275)
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#endif
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NAMESPACE_BEGIN(CryptoPP)
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/// \brief Elliptic Curve over GF(2^n)
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class CRYPTOPP_DLL EC2N : public AbstractGroup<EC2NPoint>, public EncodedPoint<EC2NPoint>
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{
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public:
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typedef GF2NP Field;
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typedef Field::Element FieldElement;
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typedef EC2NPoint Point;
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virtual ~EC2N() {}
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/// \brief Construct an EC2N
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EC2N() {}
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/// \brief Construct an EC2N
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/// \param field Field, GF2NP derived class
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/// \param a Field::Element
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/// \param b Field::Element
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EC2N(const Field &field, const Field::Element &a, const Field::Element &b)
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: m_field(field), m_a(a), m_b(b) {}
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/// \brief Construct an EC2N from BER encoded parameters
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/// \param bt BufferedTransformation derived object
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/// \details This constructor will decode and extract the fields fieldID and curve of the sequence ECParameters
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EC2N(BufferedTransformation &bt);
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/// \brief Encode the fields fieldID and curve of the sequence ECParameters
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/// \param bt BufferedTransformation derived object
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void DEREncode(BufferedTransformation &bt) const;
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bool Equal(const Point &P, const Point &Q) const;
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const Point& Identity() const;
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const Point& Inverse(const Point &P) const;
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bool InversionIsFast() const {return true;}
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const Point& Add(const Point &P, const Point &Q) const;
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const Point& Double(const Point &P) const;
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Point Multiply(const Integer &k, const Point &P) const
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{return ScalarMultiply(P, k);}
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Point CascadeMultiply(const Integer &k1, const Point &P, const Integer &k2, const Point &Q) const
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{return CascadeScalarMultiply(P, k1, Q, k2);}
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bool ValidateParameters(RandomNumberGenerator &rng, unsigned int level=3) const;
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bool VerifyPoint(const Point &P) const;
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unsigned int EncodedPointSize(bool compressed = false) const
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{return 1 + (compressed?1:2)*m_field->MaxElementByteLength();}
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// returns false if point is compressed and not valid (doesn't check if uncompressed)
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bool DecodePoint(Point &P, BufferedTransformation &bt, size_t len) const;
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bool DecodePoint(Point &P, const byte *encodedPoint, size_t len) const;
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void EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const;
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void EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
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Point BERDecodePoint(BufferedTransformation &bt) const;
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void DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
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Integer FieldSize() const {return Integer::Power2(m_field->MaxElementBitLength());}
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const Field & GetField() const {return *m_field;}
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const FieldElement & GetA() const {return m_a;}
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const FieldElement & GetB() const {return m_b;}
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bool operator==(const EC2N &rhs) const
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{return GetField() == rhs.GetField() && m_a == rhs.m_a && m_b == rhs.m_b;}
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private:
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clonable_ptr<Field> m_field;
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FieldElement m_a, m_b;
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mutable Point m_R;
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};
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CRYPTOPP_DLL_TEMPLATE_CLASS DL_FixedBasePrecomputationImpl<EC2N::Point>;
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CRYPTOPP_DLL_TEMPLATE_CLASS DL_GroupPrecomputation<EC2N::Point>;
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/// \brief Elliptic Curve precomputation
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/// \tparam EC elliptic curve field
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template <class EC> class EcPrecomputation;
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/// \brief EC2N precomputation specialization
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/// \details Implementation of <tt>DL_GroupPrecomputation<EC2N::Point></tt>
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/// \sa DL_GroupPrecomputation
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template<> class EcPrecomputation<EC2N> : public DL_GroupPrecomputation<EC2N::Point>
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{
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public:
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typedef EC2N EllipticCurve;
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virtual ~EcPrecomputation() {}
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// DL_GroupPrecomputation
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const AbstractGroup<Element> & GetGroup() const {return m_ec;}
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Element BERDecodeElement(BufferedTransformation &bt) const {return m_ec.BERDecodePoint(bt);}
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void DEREncodeElement(BufferedTransformation &bt, const Element &v) const {m_ec.DEREncodePoint(bt, v, false);}
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/// \brief Set the elliptic curve
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/// \param ec ECP derived class
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/// \details SetCurve() is not inherited
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void SetCurve(const EC2N &ec) {m_ec = ec;}
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/// \brief Get the elliptic curve
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/// \return EC2N curve
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/// \details GetCurve() is not inherited
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const EC2N & GetCurve() const {return m_ec;}
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private:
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EC2N m_ec;
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};
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NAMESPACE_END
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#if CRYPTOPP_MSC_VERSION
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# pragma warning(pop)
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#endif
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#endif
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