java.util.Random产生的随机数是有一定周期的,改进了lcg的一个版本..还是security安全点.
import java.util.Random;
/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2001</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/
public class RandomCracker {
protected static final long a=0x5deece66dL;
protected static final long b=0xbL;
protected static final long m=(1L<<48)-1;
public static void crack(int xint0,int xint1)
{
long i;
long seed=-1L;
long x0=(xint0&0xFFFFFFFFL)<<16;
long x1=(xint1&0xFFFFFFFFL);
for(i=0;i<0xFFFFL;i++){
seed=(((x0+i)*a)+b)&m;
if ((seed>>>16)==x1){
break;
}
seed=-1L;
}
if (seed==-1L)
{
throw new RuntimeException("Input Error!");}
else{
System.out.println("The Cracked x2="+(int)(((seed*a)+b&m)>>>16));
}
}
public static void main(String args[])
{
Random r=new Random();
int x0=r.nextInt();
int x1=r.nextInt();
System.out.println(" x0= "+x0);
System.out.println(" x1= "+x1);
crack(x0,x1);
System.out.println(" The Real x2="+r.nextInt());
}
}
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