CNS Lab Exercise -4

 4. Write a Java program to implement the DES algorithm logic.

import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;

import java.util.Base64;

public class DESExample {

    public static void main(String[] args) throws Exception {

        // Step 1: Create DES Key

        KeyGenerator keyGen = KeyGenerator.getInstance("DES");

        SecretKey secretKey = keyGen.generateKey();

        // Step 2: Create Cipher object

        Cipher cipher = Cipher.getInstance("DES");

        // Plain text

        String plainText = "HELLODES";

        System.out.println("Plain Text: " + plainText);

        // Step 3: Encryption

        cipher.init(Cipher.ENCRYPT_MODE, secretKey);

        byte[] encryptedBytes = cipher.doFinal(plainText.getBytes());

        String encryptedText = Base64.getEncoder().encodeToString(encryptedBytes);

        System.out.println("Encrypted Text: " + encryptedText);

        // Step 4: Decryption

        cipher.init(Cipher.DECRYPT_MODE, secretKey);

        byte[] decryptedBytes = cipher.doFinal(encryptedBytes);

        String decryptedText = new String(decryptedBytes);

        System.out.println("Decrypted Text: " + decryptedText);

    }

}

Output:

Plain Text: HELLODES

Encrypted Text: pZK3XyMZ8kE=

Decrypted Text: HELLODES