Practical No-3

AIM: To Implement Diffie-Hellman Key Exchange Algorithm in Java

 import java.util.*;

import java.math.BigInteger.*;

import java.math.*;

class diffiehellman

{public static void main(String args[])

{

BigInteger A, B, K1, K2, x, y, g, n;

Scanner s = new Scanner(System.in);

System.out.println("Enter A’s prime number!");

n = s.nextBigInteger();

System.out.println("Enter B’s prime number!");

g = s.nextBigInteger();

System.out.println("Enter A’s secret key!");

x = s.nextBigInteger();

System.out.println("This key is sent to B!");

System.out.println("Enter B’s secret key!");

y = s.nextBigInteger();

System.out.println("This key is sent to A!");

A = g.modPow(x, n);

B = g.modPow(y, n);

K1 = B.modPow(x, n);

K2 = A.modPow(y, n);

System.out.println("A’s key is " + K1);

System.out.println("B’s key is " + K2);

}

}