ecc_java_implement.zip_ecc_ecc java_ecc加密_ecc加密字符串

package com.eshore.dep.util.security.ecc; //package ecc.elliptic; import java.math.BigInteger; import java.util.Arrays; import java.io.*; public class ECPoint { public final static BigInteger TWO = new BigInteger("2"); public final static BigInteger THREE = new BigInteger("3"); private EllipticCurve mother; private BigInteger x, y; private boolean iszero; private ECPoint[] fastcache = null; //fastcache is an array of ECPoints private ECPoint[] cache = null; //Even cache is an ECPoint array public void fastCache() { try { if(fastcache == null) { fastcache = new ECPoint[256]; //fastcache initialised to 256 EC Points. fastcache[0] = new ECPoint(mother); //First point is null. for(int i = 1; i < fastcache.length; i++) //From 1 to 256 { fastcache[i] = fastcache[i-1].add(this); //add the point repeatedly (Cumulative sum). P,2P,... } } } catch (NoCommonMotherException e) { System.out.println("ECPoint.fastcache: THIS CANNOT HAPPEN!!!"); } } /** Constructs a point on an elliptic curve. *@param mother The elliptic curve on wich the point is surposed to lie *@param x the x coordinate of the point *@param y the y coordinate of the point *@exception Throws a NotOnMotherException if (x,y) is not on the mother curve.*/ public ECPoint(EllipticCurve mother, BigInteger x, BigInteger y) throws NotOnMotherException { this.mother = mother; this.x = x; this.y = y; if (!mother.onCurve(this)) throw new NotOnMotherException(this); iszero = false; } /** Decompresses a compressed point stored in a byte-array into a new ECPoint. *@param bytes the array of bytes to be decompressed *@param mother the EllipticCurve the decompressed point is supposed to lie on.*/ public ECPoint(byte[] bytes, EllipticCurve mother) { this.mother = mother; if (bytes[0] == 2) { iszero = true; return; } boolean ymt = false; if(bytes[0] != 0) ymt = true; bytes[0] = 0; x = new BigInteger(bytes); if(mother.getPPODBF() == null) System.out.println("Fuck dig!!!"); y = x.multiply(x).add(mother.geta()).multiply(x).add(mother.getb()).modPow(mother.getPPODBF(),mother.getp()); if(ymt != y.testBit(0)) { y = mother.getp().subtract(y); } iszero = false; } /** IMPORTANT this renders the values of x and y to be null! Use this constructor *only to create instances of a Zero class!*/ public ECPoint(EllipticCurve e){ x = y = BigInteger.ZERO; mother = e; iszero = true; } public byte[] compress() { byte[] cmp = new byte[mother.getPCS()]; if (iszero) { cmp[0] = 2; } byte[] xb = x.toByteArray(); System.arraycopy(xb, 0, cmp, mother.getPCS()-xb.length, xb.length); if(y.testBit(0)) cmp[0] = 1; return cmp; } /** Adds another elliptic curve point to this point. *@param q The point to be added *@return the sum of this point on the argument *@exception Throws a NoCommonMotherException if the two points don't lie on the same elliptic curve.*/ public ECPoint add(ECPoint q) throws NoCommonMotherException { if (!hasCommonMother(q)) throw new NoCommonMotherException(); if (this.iszero) return q; else if (q.isZero()) return this; BigInteger y1 = y; BigInteger y2 = q.gety(); BigInteger x1 = x; BigInteger x2 = q.getx(); BigInteger alpha; if (x2.compareTo(x1) == 0) { if (!(y2.compareTo(y1) == 0)) return new ECPoint(mother); else { alpha = ((x1.modPow(TWO,mother.getp())).multiply(THREE)).add(mother.geta()); alpha = (alpha.multiply((TWO.multiply(y1)).modInverse(mother.getp()))).mod(mother.getp()); } } else { alpha = ((y2.subtract(y1)).multiply((x2.subtract(x1)).modInverse(mother.getp()))).mod(mother.getp()); } BigInteger x3,y3; x3 = (((alpha.modPow(TWO,mother.getp())).subtract(x2)).subtract(x1)).mod(mother.getp()); y3 = ((alpha.multiply(x1.subtract(x3))).subtract(y1)).mod(mother.getp()); try { return new ECPoint(mother,x3,y3); } catch (NotOnMotherException e) { System.out.println("Error in add!!! Result not on mother!"); return null; } } public ECPoint multiply(BigInteger coef) { /*try{ ECPoint result = new ECPoint(mother); //result is initialised to null byte[] coefb = coef.toByteArray(); //coefb is the number to be multiplied. i.e. q in p*q. called as p.mul(q) if(fastcache != null) //fastcache of this, i.e. p { for(int i = 0; i < coefb.length; i++) { result = result.times256().add(fastcache[coefb[i]&255]); // result=result*256+fastcache(coefb[i]&255) } return result; } if(cache == null) //If cache is empty, populate it upto 16 { cache = new ECPoint[16]; cache[0] = new ECPoint(mother); for(int i = 1; i < cache.length; i++) { cache[i] = cache[i-1].add(this); } } for(int i = 0; i < coefb.length; i++) { result = result.times16().add(cache[(coefb[i]>>4)&15]).times16().add(cache[coefb[i]&15]); } return result; } catch (NoCommonMotherException e) { System.out.println("Error in pow!!!"); return null; }*/ // //BigInteger R0=this.getx(); //BigInteger R1=R0.add(R0); //Convert multiplier into binary. String BitNum=coef.toString(2); // System.out.println(coef+"in bin form is"+BitNum); // System.out.println("length of bitnum string is"+BitNum.length()); int nk=coef.bitCount(); //nk in paper. // System.out.println(coef+" .bitcount is "+ nk); ECPoint result=this; for(int i=nk-1;i>0;i--) { try { result=result.add(result); if(coef.testBit(i)) result=result.add(this); } catch(Exception e) { System.out.println("Error in multiplying"); } } /*if(!coef.testBit(i)) { R1=R0.add(R1); R0=R0.add(R0); } else { R0=R0.add(R1); R1=R1.add(R1); }*/ //ECPoint result=new ECPoint(this.mother); //result.x=R0; //BigInteger y0=R0.multiply(R0).add(this.mother.geta()).multiply(R0).add(this.mother.getb()).modPow(this.mother.getPPODBF(),this.mother.getp()); //result.y=y0; return result; } private ECPoint times16() { try { ECPoint result = this; for(int i = 0; i < 4; i++) { result = result.add(result); } return result; } catch (Exception e) { System.out.println("ECPoint.times16: THIS CANNOT HAPPEN!!!"); return null; } } private ECPoint times256() { try { ECPoint result = this; for(int i = 0; i < 8; i++) { result = result.add(result); } return result; } catch (Exception e) { System.out.println("ECPoint.times256: THIS CANNOT HAPPEN!!!"); return null; } } public BigInteger getx() { return x; } public BigInteger gety() { return y; } public EllipticCurve getMother() { return mother; } public String toString() { return "(" + x.toString() + ", " + y.toString() + ")"; } public boolean hasCommonMother(ECPoint p) { if (this.mother.equals(p.getMother())) return true; else return false; } public boolean isZero() { return iszero; } }