147 lines
5.3 KiB
C++
147 lines
5.3 KiB
C++
// ecpoint.h - written and placed in the public domain by Jeffrey Walton
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// Data structures moved from ecp.h and ec2n.h. Added EncodedPoint interface
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/// \file ecpoint.h
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/// \brief Classes for Elliptic Curve points
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/// \since Crypto++ 6.0
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#ifndef CRYPTOPP_ECPOINT_H
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#define CRYPTOPP_ECPOINT_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 "gf2n.h"
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NAMESPACE_BEGIN(CryptoPP)
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/// \brief Elliptical Curve Point over GF(p), where p is prime
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/// \since Crypto++ 2.0
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struct CRYPTOPP_DLL ECPPoint
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{
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virtual ~ECPPoint() {}
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/// \brief Construct an ECPPoint
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/// \details identity is set to <tt>true</tt>
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ECPPoint() : identity(true) {}
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/// \brief Construct an ECPPoint from coordinates
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/// \details identity is set to <tt>false</tt>
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ECPPoint(const Integer &x, const Integer &y)
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: x(x), y(y), identity(false) {}
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/// \brief Tests points for equality
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/// \param t the other point
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/// \return true if the points are equal, false otherwise
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bool operator==(const ECPPoint &t) const
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{return (identity && t.identity) || (!identity && !t.identity && x==t.x && y==t.y);}
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/// \brief Tests points for ordering
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/// \param t the other point
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/// \return true if this point is less than other, false otherwise
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bool operator< (const ECPPoint &t) const
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{return identity ? !t.identity : (!t.identity && (x<t.x || (x==t.x && y<t.y)));}
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Integer x, y;
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bool identity;
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};
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CRYPTOPP_DLL_TEMPLATE_CLASS AbstractGroup<ECPPoint>;
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/// \brief Elliptical Curve Point over GF(2^n)
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/// \since Crypto++ 2.0
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struct CRYPTOPP_DLL EC2NPoint
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{
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virtual ~EC2NPoint() {}
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/// \brief Construct an EC2NPoint
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/// \details identity is set to <tt>true</tt>
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EC2NPoint() : identity(true) {}
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/// \brief Construct an EC2NPoint from coordinates
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/// \details identity is set to <tt>false</tt>
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EC2NPoint(const PolynomialMod2 &x, const PolynomialMod2 &y)
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: x(x), y(y), identity(false) {}
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/// \brief Tests points for equality
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/// \param t the other point
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/// \return true if the points are equal, false otherwise
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bool operator==(const EC2NPoint &t) const
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{return (identity && t.identity) || (!identity && !t.identity && x==t.x && y==t.y);}
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/// \brief Tests points for ordering
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/// \param t the other point
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/// \return true if this point is less than other, false otherwise
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bool operator< (const EC2NPoint &t) const
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{return identity ? !t.identity : (!t.identity && (x<t.x || (x==t.x && y<t.y)));}
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PolynomialMod2 x, y;
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bool identity;
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};
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CRYPTOPP_DLL_TEMPLATE_CLASS AbstractGroup<EC2NPoint>;
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/// \brief Abstract class for encoding and decoding ellicptic curve points
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/// \tparam Point ellicptic curve point
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/// \details EncodedPoint is an interface for encoding and decoding elliptic curve points.
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/// The template parameter <tt>Point</tt> should be a class like ECP or EC2N.
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/// \since Crypto++ 6.0
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template <class Point>
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class EncodedPoint
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{
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public:
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virtual ~EncodedPoint() {}
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/// \brief Decodes an elliptic curve point
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/// \param P point which is decoded
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/// \param bt source BufferedTransformation
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/// \param len number of bytes to read from the BufferedTransformation
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/// \return true if a point was decoded, false otherwise
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virtual bool DecodePoint(Point &P, BufferedTransformation &bt, size_t len) const =0;
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/// \brief Decodes an elliptic curve point
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/// \param P point which is decoded
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/// \param encodedPoint byte array with the encoded point
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/// \param len the size of the array
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/// \return true if a point was decoded, false otherwise
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virtual bool DecodePoint(Point &P, const byte *encodedPoint, size_t len) const =0;
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/// \brief Verifies points on elliptic curve
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/// \param P point to verify
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/// \return true if the point is valid, false otherwise
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virtual bool VerifyPoint(const Point &P) const =0;
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/// \brief Determines encoded point size
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/// \param compressed flag indicating if the point is compressed
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/// \return the minimum number of bytes required to encode the point
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virtual unsigned int EncodedPointSize(bool compressed = false) const =0;
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/// \brief Encodes an elliptic curve point
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/// \param P point which is decoded
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/// \param encodedPoint byte array for the encoded point
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/// \param compressed flag indicating if the point is compressed
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/// \details <tt>encodedPoint</tt> must be at least EncodedPointSize() in length
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virtual void EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const =0;
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/// \brief Encodes an elliptic curve point
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/// \param bt target BufferedTransformation
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/// \param P point which is encoded
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/// \param compressed flag indicating if the point is compressed
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virtual void EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const =0;
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/// \brief BER Decodes an elliptic curve point
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/// \param bt source BufferedTransformation
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/// \return the decoded elliptic curve point
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virtual Point BERDecodePoint(BufferedTransformation &bt) const =0;
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/// \brief DER Encodes an elliptic curve point
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/// \param bt target BufferedTransformation
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/// \param P point which is encoded
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/// \param compressed flag indicating if the point is compressed
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virtual void DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const =0;
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};
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NAMESPACE_END
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#endif // CRYPTOPP_ECPOINT_H
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