Hkzyn49C

1import java.math.*;
2import java.util.*;
3import java.security.*;
4import java.io.*;
5public class elgamel
6{
7    public static void main(String[] args) throws IOException
8    {
9        BigInteger p, b, c, secretKey;
10        Scanner ssc=new Scanner(System.in);
11        Random sc = new SecureRandom();
12        secretKey = new BigInteger("12345678901234567890");
13       //Calculating Public key
14        System.out.println("secretKey = " + secretKey);
15        p = BigInteger.probablePrime(64, sc);
16        b = new BigInteger("3");
17        c = b.modPow(secretKey, p);
18        System.out.println("p = " + p);
19        System.out.println("b = " + b);
20        System.out.println("c = " + c);
21        //Encrytping
22        System.out.print("Enter the number to encrypt");
23        String s = ssc.nextLine();
24        BigInteger X = new BigInteger(s);
25        BigInteger r = new BigInteger(64, sc);
26        BigInteger EC = X.multiply(c.modPow(r, p)).mod(p);
27        BigInteger brmodp = b.modPow(r, p);
28        System.out.println("Plaintext = " + X);
29        System.out.println("r = " + r);
30        System.out.println("EC = " + EC);
31        System.out.println("b^r mod p = " + brmodp);
32        //Decrypting
33        BigInteger crmodp = brmodp.modPow(secretKey, p);
34        BigInteger d = crmodp.modInverse(p);
35        BigInteger ad = d.multiply(EC).mod(p);
36        System.out.println("\n\nc^r mod p = " + crmodp);
37        System.out.println("d = " + d);
38        System.out.println("Decrypted msg " + ad);
39
40    }
41}