/*
 Encryption works at the byte level, so almost anything can be encrypted. 
 Once you have a key and a cipher, you're ready to go. It should be noted 
 that the same algorithm must be used for both the key and cipher. 
 You cannot have a key initialized with DESede and a cipher initialized 
 with DES. The Cipher object uses the same methods to encrypt and decrypt 
 data, so you must initialize it first to let it know what you want done 
 with the data:
*/

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.BadPaddingException;
import java.security.Key;
import java.security.Security;
import java.security.NoSuchAlgorithmException;
import java.security.InvalidKeyException;

public class DESCryptoTest {
    
    public static void main(String[] args) {
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        try {
            KeyGenerator kg = KeyGenerator.getInstance("DES");
            Key key = kg.generateKey();
            Cipher cipher = Cipher.getInstance("DES");
            byte[] data = "Hello World!".getBytes();
            System.out.println("Original data : " + new String(data));
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] result = cipher.doFinal(data);
            System.out.println("Encrypted data: " + new String(result));
            cipher.init(Cipher.DECRYPT_MODE, key);
            byte[] original = cipher.doFinal(result);
            System.out.println("Decrypted data: " + new String(original));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
    }
}