1#ifndef CRYPTOPP_ECP_H
2#define CRYPTOPP_ECP_H
3
4#include "modarith.h"
5#include "eprecomp.h"
6#include "smartptr.h"
7#include "pubkey.h"
8
9NAMESPACE_BEGIN(CryptoPP)
10
11//! Elliptical Curve Point
12struct CRYPTOPP_DLL ECPPoint
13{
14	ECPPoint() : identity(true) {}
15	ECPPoint(const Integer &x, const Integer &y)
16		: identity(false), x(x), y(y) {}
17
18	bool operator==(const ECPPoint &t) const
19		{return (identity && t.identity) || (!identity && !t.identity && x==t.x && y==t.y);}
20	bool operator< (const ECPPoint &t) const
21		{return identity ? !t.identity : (!t.identity && (x<t.x || (x==t.x && y<t.y)));}
22
23	bool identity;
24	Integer x, y;
25};
26
27CRYPTOPP_DLL_TEMPLATE_CLASS AbstractGroup<ECPPoint>;
28
29//! Elliptic Curve over GF(p), where p is prime
30class CRYPTOPP_DLL ECP : public AbstractGroup<ECPPoint>
31{
32public:
33	typedef ModularArithmetic Field;
34	typedef Integer FieldElement;
35	typedef ECPPoint Point;
36
37	ECP() {}
38	ECP(const ECP &ecp, bool convertToMontgomeryRepresentation = false);
39	ECP(const Integer &modulus, const FieldElement &a, const FieldElement &b)
40		: m_fieldPtr(new Field(modulus)), m_a(a.IsNegative() ? modulus+a : a), m_b(b) {}
41	// construct from BER encoded parameters
42	// this constructor will decode and extract the the fields fieldID and curve of the sequence ECParameters
43	ECP(BufferedTransformation &bt);
44
45	// encode the fields fieldID and curve of the sequence ECParameters
46	void DEREncode(BufferedTransformation &bt) const;
47
48	bool Equal(const Point &P, const Point &Q) const;
49	const Point& Identity() const;
50	const Point& Inverse(const Point &P) const;
51	bool InversionIsFast() const {return true;}
52	const Point& Add(const Point &P, const Point &Q) const;
53	const Point& Double(const Point &P) const;
54	Point ScalarMultiply(const Point &P, const Integer &k) const;
55	Point CascadeScalarMultiply(const Point &P, const Integer &k1, const Point &Q, const Integer &k2) const;
56	void SimultaneousMultiply(Point *results, const Point &base, const Integer *exponents, unsigned int exponentsCount) const;
57
58	Point Multiply(const Integer &k, const Point &P) const
59		{return ScalarMultiply(P, k);}
60	Point CascadeMultiply(const Integer &k1, const Point &P, const Integer &k2, const Point &Q) const
61		{return CascadeScalarMultiply(P, k1, Q, k2);}
62
63	bool ValidateParameters(RandomNumberGenerator &rng, unsigned int level=3) const;
64	bool VerifyPoint(const Point &P) const;
65
66	unsigned int EncodedPointSize(bool compressed = false) const
67		{return 1 + (compressed?1:2)*GetField().MaxElementByteLength();}
68	// returns false if point is compressed and not valid (doesn't check if uncompressed)
69	bool DecodePoint(Point &P, BufferedTransformation &bt, size_t len) const;
70	bool DecodePoint(Point &P, const byte *encodedPoint, size_t len) const;
71	void EncodePoint(byte *encodedPoint, const Point &P, bool compressed) const;
72	void EncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
73
74	Point BERDecodePoint(BufferedTransformation &bt) const;
75	void DEREncodePoint(BufferedTransformation &bt, const Point &P, bool compressed) const;
76
77	Integer FieldSize() const {return GetField().GetModulus();}
78	const Field & GetField() const {return *m_fieldPtr;}
79	const FieldElement & GetA() const {return m_a;}
80	const FieldElement & GetB() const {return m_b;}
81
82	bool operator==(const ECP &rhs) const
83		{return GetField() == rhs.GetField() && m_a == rhs.m_a && m_b == rhs.m_b;}
84
85private:
86	clonable_ptr<Field> m_fieldPtr;
87	FieldElement m_a, m_b;
88	mutable Point m_R;
89};
90
91CRYPTOPP_DLL_TEMPLATE_CLASS DL_FixedBasePrecomputationImpl<ECP::Point>;
92CRYPTOPP_DLL_TEMPLATE_CLASS DL_GroupPrecomputation<ECP::Point>;
93
94template <class T> class EcPrecomputation;
95
96//! ECP precomputation
97template<> class EcPrecomputation<ECP> : public DL_GroupPrecomputation<ECP::Point>
98{
99public:
100	typedef ECP EllipticCurve;
101
102	// DL_GroupPrecomputation
103	bool NeedConversions() const {return true;}
104	Element ConvertIn(const Element &P) const
105		{return P.identity ? P : ECP::Point(m_ec->GetField().ConvertIn(P.x), m_ec->GetField().ConvertIn(P.y));};
106	Element ConvertOut(const Element &P) const
107		{return P.identity ? P : ECP::Point(m_ec->GetField().ConvertOut(P.x), m_ec->GetField().ConvertOut(P.y));}
108	const AbstractGroup<Element> & GetGroup() const {return *m_ec;}
109	Element BERDecodeElement(BufferedTransformation &bt) const {return m_ec->BERDecodePoint(bt);}
110	void DEREncodeElement(BufferedTransformation &bt, const Element &v) const {m_ec->DEREncodePoint(bt, v, false);}
111
112	// non-inherited
113	void SetCurve(const ECP &ec)
114	{
115		m_ec.reset(new ECP(ec, true));
116		m_ecOriginal = ec;
117	}
118	const ECP & GetCurve() const {return *m_ecOriginal;}
119
120private:
121	value_ptr<ECP> m_ec, m_ecOriginal;
122};
123
124NAMESPACE_END
125
126#endif
127