用java编程实现Diffie-Hellman算法

Diffie-Hellman密钥交换代码如下:
import
java.util.ArrayList;
import
java.util.List;
import
java.util.Random;
import
java.math.*;

public class
DHtest {

public static void main(String[]
args){

System.out.println("Alice和Bob确定一个4位的随机大素数n, 5位的随机大素数g");
//获得一个4位数的随机大素数
long longPrimeVar4_n =
createRadomPrimeNunber(4);
System.out.println("n="+longPrimeVar4_n);
//获得一个5位数的随机大素数
long longPrimeVar5_g =
createRadomPrimeNunber(5);
System.out.println("g="+longPrimeVar5_g);

//获得一个4位的随机大数
long longVar4_x = createRandomNumber(3);
System.out.println("Alice选择一个3位的大随机数x="+longVar4_x);
//获得一个5位的随机大数
long longVar5_y = createRandomNumber(3);
System.out.println("Bob选择一个3位的大随机数y="+longVar5_y);

//计算A,B
long
A = (long)largeMOD(longPrimeVar5_g,longVar4_x,longPrimeVar4_n);
System.out.println("Alice根据x计算出A="+A+" 并发给Bob");
long
B = (long)largeMOD(longPrimeVar5_g,longVar5_y,longPrimeVar4_n);
System.out.println("Bob根据y计算出B="+B+" 并发给Alice");

//计算K1，K2
long
K1 = (long)largeMOD(B,longVar4_x,longPrimeVar4_n);
System.out.println("Alice根据B计算出密匙K1="+K1);
long
K2 =
(long)largeMOD(A,longVar5_y,longPrimeVar4_n);
System.out.println("Bob根据A计算出密匙K2="+K2);

//判断K1是否等于k2
if(K1==K2) {
System.out.println("K1=K2");
}
else
{
System.out.println("error");
}

}

/*
* 产生随机的大素数
*/
public static long
createRadomPrimeNunber(int n){
long recLong
= 0;
List
list = listAllPrimeNumber(n);
Random
rd = new
Random();
int
randomIndex = Math.abs( rd.nextInt()%list.size());
recLong =
((Long)list.get(randomIndex)).longValue();
return
recLong;

}

public
static List listAllPrimeNumber(int n){
List
list = new
ArrayList();
long
low = (long)Math.pow(10,n-1);
long
high = (long)Math.pow(10,n) -
1;
for(long i= low; i < high; i++){
if(isPrimeNumber(i)) {

list.add(new Long(i));
}
}
return
list;

}

//定义一个判断一个数是否是素数的函数
public
static boolean isPrimeNumber(long x){

if(isProbablePrime(x))
return true;
else
return false;
}
private static boolean isProbablePrime(long
x) {
return
true;
}

/*
* 产生大的随机数
*/
public
static long createRandomNumber(int n){
long recLong
= 0;
List
list = listAllPrimeNumber(n);
Random
rd = new
Random();
int
randomIndex = Math.abs( rd.nextInt()%list.size());
recLong =
((Long)list.get(randomIndex)).longValue();
return
recLong;

}
public
static List listAllNumber(int n){
List list2 = new ArrayList();
long low = (long)Math.pow(10,n-1);
long high = (long)Math.pow(10,n) - 1;
for(long i= low; i < high; i++){

list2.add(new Long(i));

}

return
list2;
}

public static double largeMOD(long x,long
y,long z)
{
if(y==1)
return
x%z;
else
{
--y;
return
((x%z) * largeMOD(x,y,z)) % z ;
}
}
}