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167 lines
6.1 KiB
167 lines
6.1 KiB
// ecp.h - originally written and placed in the public domain by Wei Dai |
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/// \file ecp.h |
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/// \brief Classes for Elliptic Curves over prime fields |
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#ifndef CRYPTOPP_ECP_H |
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#define CRYPTOPP_ECP_H |
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#include "cryptlib.h" |
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#include "integer.h" |
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#include "algebra.h" |
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#include "modarith.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(p), where p is prime |
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class CRYPTOPP_DLL ECP : public AbstractGroup<ECPPoint>, public EncodedPoint<ECPPoint> |
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{ |
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public: |
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typedef ModularArithmetic Field; |
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typedef Integer FieldElement; |
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typedef ECPPoint Point; |
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virtual ~ECP() {} |
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/// \brief Construct an ECP |
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ECP() {} |
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/// \brief Construct an ECP |
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/// \param ecp the other ECP object |
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/// \param convertToMontgomeryRepresentation flag indicating if the curve |
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/// should be converted to a MontgomeryRepresentation. |
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/// \details Prior to Crypto++ 8.3 the default value for |
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/// convertToMontgomeryRepresentation was false. it was changed due to |
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/// two audit tools finding, "Signature-compatible with a copy constructor". |
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/// \sa ModularArithmetic, MontgomeryRepresentation |
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ECP(const ECP &ecp, bool convertToMontgomeryRepresentation); |
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/// \brief Construct an ECP |
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/// \param modulus the prime modulus |
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/// \param a Field::Element |
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/// \param b Field::Element |
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ECP(const Integer &modulus, const FieldElement &a, const FieldElement &b) |
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: m_fieldPtr(new Field(modulus)), m_a(a.IsNegative() ? modulus+a : a), m_b(b) {} |
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/// \brief Construct an ECP 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 the fields |
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/// fieldID and curve of the sequence ECParameters |
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ECP(BufferedTransformation &bt); |
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/// \brief DER Encode |
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/// \param bt BufferedTransformation derived object |
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/// \details DEREncode encode the fields fieldID and curve of the sequence |
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/// ECParameters |
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void DEREncode(BufferedTransformation &bt) const; |
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/// \brief Compare two points |
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/// \param P the first point |
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/// \param Q the second point |
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/// \returns true if equal, false otherwise |
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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 ScalarMultiply(const Point &P, const Integer &k) const; |
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Point CascadeScalarMultiply(const Point &P, const Integer &k1, const Point &Q, const Integer &k2) const; |
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void SimultaneousMultiply(Point *results, const Point &base, const Integer *exponents, unsigned int exponentsCount) 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)*GetField().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 GetField().GetModulus();} |
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const Field & GetField() const {return *m_fieldPtr;} |
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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 ECP &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_fieldPtr; |
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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<ECP::Point>; |
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CRYPTOPP_DLL_TEMPLATE_CLASS DL_GroupPrecomputation<ECP::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 ECP precomputation specialization |
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/// \details Implementation of <tt>DL_GroupPrecomputation<ECP::Point></tt> with input and output |
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/// conversions for Montgomery modular multiplication. |
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/// \sa DL_GroupPrecomputation, ModularArithmetic, MontgomeryRepresentation |
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template<> class EcPrecomputation<ECP> : public DL_GroupPrecomputation<ECP::Point> |
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{ |
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public: |
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typedef ECP EllipticCurve; |
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virtual ~EcPrecomputation() {} |
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// DL_GroupPrecomputation |
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bool NeedConversions() const {return true;} |
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Element ConvertIn(const Element &P) const |
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{return P.identity ? P : ECP::Point(m_ec->GetField().ConvertIn(P.x), m_ec->GetField().ConvertIn(P.y));}; |
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Element ConvertOut(const Element &P) const |
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{return P.identity ? P : ECP::Point(m_ec->GetField().ConvertOut(P.x), m_ec->GetField().ConvertOut(P.y));} |
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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 ECP &ec) |
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{ |
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m_ec.reset(new ECP(ec, true)); |
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m_ecOriginal = ec; |
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} |
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/// \brief Get the elliptic curve |
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/// \returns ECP curve |
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/// \details GetCurve() is not inherited |
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const ECP & GetCurve() const {return *m_ecOriginal;} |
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private: |
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value_ptr<ECP> m_ec, m_ecOriginal; |
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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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