www.pudn.com > miracl.zip > EC2.H

/* 
 *    MIRACL  C++ Header file ec2.h 
 * 
 *    AUTHOR  : M. Scott 
 *   
 *    PURPOSE : Definition of class EC2  (Arithmetic on an Elliptic Curve, 
 *               over GF(2^m) 
 * 
 *    NOTE    : Must be used in conjunction with ec2.cpp and big.cpp 
 *              The active curve is set dynamically (via the Big ecurve2()  
 *              routine) - so beware the pitfalls implicit in declaring 
 *              static or global EC2's (which are initialised before the  
 *              curve is set!). Uninitialised data is OK  
 * 
 *    Copyright (c) 2000 Shamus Software Ltd. 
 */ 
 
#ifndef EC2_H 
#define EC2_H 
 
#include  
 
class EC2 
{ 
    epoint *p; 
public: 
    EC2()                         { p=epoint2_init();} 
    
    EC2(const Big &x,const Big& y)  {p=epoint2_init();  
                                   epoint2_set(x.getbig(),y.getbig(),0,p); } 
     
  // This next constructor restores a point on the curve from "compressed"  
  // data, that is the full x co-ordinate, and the LSB of y/x  (0 or 1) 
 
    EC2(const Big& x,int cb)       {p=epoint2_init(); 
                                   epoint2_set(x.getbig(),x.getbig(),cb,p); } 
                    
    EC2(const EC2 &b)             {p=epoint2_init(); epoint2_copy(b.p,p);} 
 
    epoint *get_point() const; 
     
    EC2& operator=(const EC2& b)  {epoint2_copy(b.p,p);return *this;} 
 
    EC2& operator+=(const EC2& b) {ecurve2_add(b.p,p); return *this;} 
    EC2& operator-=(const EC2& b) {ecurve2_sub(b.p,p); return *this;} 
 
  // Multiplication of a point by an integer.  
 
    EC2& operator*=(const Big& k) {ecurve2_mult(k.getbig(),p,p); return *this;} 
    big add(const EC2& b)         {return ecurve2_add(b.p,p); }  
                                  // returns line slope as a big 
    big sub(const EC2& b)         {return ecurve2_sub(b.p,p); } 
 
    void clear() {epoint2_set(NULL,NULL,0,p);} 
    BOOL set(const Big& x,const Big& y)    {return epoint2_set(x.getbig(),y.getbig(),0,p);} 
    int get(Big& x,Big& y) const; 
    BOOL iszero() const; 
  // This gets the point in compressed form. Return value is LSB of y-coordinate 
    int get(Big& x) const; 
 
  // point compression 
 
  // This sets the point from compressed form. cb is LSB of y/x  
 
    BOOL set(const Big& x,int cb=0)  {return epoint2_set(x.getbig(),x.getbig(),cb,p);} 
 
    friend EC2 operator-(const EC2&); 
    friend void multi_add(int,EC2 *,EC2 *); 
   
    friend EC2 mul(const Big&, const EC2&, const Big&, const EC2&); 
    friend EC2 mul(int, const Big *, EC2 *); 
   
    friend void normalise(EC2 &e) {epoint2_norm(e.p);} 
 
    friend BOOL operator==(const EC2& a,const EC2& b) 
                                  {return epoint2_comp(a.p,b.p);}     
    friend BOOL operator!=(const EC2& a,const EC2& b) 
                                  {return (!epoint2_comp(a.p,b.p));}     
 
    friend EC2 operator*(const Big &,const EC2&); 
 
#ifndef MR_NO_STANDARD_IO 
 
    friend ostream& operator<<(ostream&,const EC2&); 
 
#endif 
 
    ~EC2() {epoint2_free(p); } 
 
}; 
 
#endif