From a3b6ece7ab341b5b14135baeccea7d5e4c086771 Mon Sep 17 00:00:00 2001
From: weidai <weidai11@users.noreply.github.com>
Date: Fri, 4 Oct 2002 17:31:41 +0000
Subject: Initial revision

---
 ec2n.h | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 ec2n.h

(limited to 'ec2n.h')

diff --git a/ec2n.h b/ec2n.h
new file mode 100644
index 00000000..c2177e76
--- /dev/null
+++ b/ec2n.h
@@ -0,0 +1,105 @@
+#ifndef CRYPTOPP_EC2N_H
+#define CRYPTOPP_EC2N_H
+
+#include "gf2n.h"
+#include "eprecomp.h"
+#include "smartptr.h"
+#include "pubkey.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+//! Elliptic Curve Point
+struct EC2NPoint
+{
+	EC2NPoint() : identity(true) {}
+	EC2NPoint(const PolynomialMod2 &x, const PolynomialMod2 &y)
+		: identity(false), x(x), y(y) {}
+
+	bool operator==(const EC2NPoint &t) const
+		{return (identity && t.identity) || (!identity && !t.identity && x==t.x && y==t.y);}
+	bool operator< (const EC2NPoint &t) const
+		{return identity ? !t.identity : (!t.identity && (x<t.x || (x==t.x && y<t.y)));}
+
+	bool identity;
+	PolynomialMod2 x, y;
+};
+
+//! Elliptic Curve over GF(2^n)
+class EC2N : public AbstractGroup<EC2NPoint>
+{
+public:
+	typedef GF2NP Field;
+	typedef Field::Element FieldElement;
+	typedef EC2NPoint Point;
+
+	EC2N() {}
+	EC2N(const Field &field, const Field::Element &a, const Field::Element &b)
+		: m_field(field), m_a(a), m_b(b) {}
+	// construct from BER encoded parameters
+	// this constructor will decode and extract the the fields fieldID and curve of the sequence ECParameters
+	EC2N(BufferedTransformation &bt);
+
+	// encode the fields fieldID and curve of the sequence ECParameters
+	void DEREncode(BufferedTransformation &bt) const;
+
+	bool Equal(const Point &P, const Point &Q) const;
+	const Point& Identity() const;
+	const Point& Inverse(const Point &P) const;
+	bool InversionIsFast() const {return true;}
+	const Point& Add(const Point &P, const Point &Q) const;
+	const Point& Double(const Point &P) const;
+
+	Point Multiply(const Integer &k, const Point &P) const
+		{return ScalarMultiply(P, k);}
+	Point CascadeMultiply(const Integer &k1, const Point &P, const Integer &k2, const Point &Q) const
+		{return CascadeScalarMultiply(P, k1, Q, k2);}
+
+	bool ValidateParameters(RandomNumberGenerator &rng, unsigned int level=3) const;
+	bool VerifyPoint(const Point &P) const;
+
+	unsigned int EncodedPointSize(bool compressed = false) const
+		{return 1 + (compressed?1:2)*m_field->MaxElementByteLength();}
+	// returns false if point is compressed and not valid (doesn't check if uncompressed)
+	bool DecodePoint(Point &P, BufferedTransformation &bt, unsigned int len) const;
+	bool DecodePoint(Point &P, const byte *encodedPoint, unsigned int len) const;
+	void EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const;
+	void EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
+
+	Point BERDecodePoint(BufferedTransformation &bt) const;
+	void DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
+
+	Integer FieldSize() const {return Integer::Power2(m_field->MaxElementBitLength());}
+	const Field & GetField() const {return *m_field;}
+	const FieldElement & GetA() const {return m_a;}
+	const FieldElement & GetB() const {return m_b;}
+
+private:
+	clonable_ptr<Field> m_field;
+	FieldElement m_a, m_b;
+	mutable Point m_R;
+};
+
+template <class T> class EcPrecomputation;
+
+//! .
+template<> class EcPrecomputation<EC2N> : public DL_GroupPrecomputation<EC2N::Point>
+{
+public:
+	typedef EC2N EllipticCurve;
+
+	// DL_GroupPrecomputation
+	const AbstractGroup<Element> & GetGroup() const {return m_ec;}
+	Element BERDecodeElement(BufferedTransformation &bt) const {return m_ec.BERDecodePoint(bt);}
+	void DEREncodeElement(BufferedTransformation &bt, const Element &v) const {m_ec.DEREncodePoint(bt, v, false);}
+
+	// non-inherited
+	void SetCurve(const EC2N &ec) {m_ec = ec;}
+	const EC2N & GetCurve() const {return m_ec;}
+
+private:
+	EC2N m_ec;
+};
+
+NAMESPACE_END
+
+#endif
-- 
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