AES Cryption

import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * Uses AES to encrypt and decrypt a message.
 *
 * @author CENSORED FOR JU DYLAN
 */
public class AES {

    /**
     * The message.
     */
    private static final String MESSAGE = "Hello world!";

    /**
     * The key generator instance.
     */
    private static KeyGenerator keyGenerator;

    /**
     * The secret key spec instance.
     */
    private static SecretKeySpec secretkeySpec;

    /**
     * The cipher instance.
     */
    private static Cipher cipher;

    /**
     * The secret key instance.
     */
    private static SecretKey secretKey;

    /**
     * The key size.
     */
    private static final int KEY_SIZE = 128;

    /**
     * Decrypts the message.
     *
     * @param encrypted
     *            The encrypted message.
     * @return The decrypted message.
     */
    private static String decrypt(byte[] encrypted) {
        try {
            cipher.init(Cipher.DECRYPT_MODE, secretkeySpec);
            return new String(cipher.doFinal(encrypted));
        } catch (Exception ex) {
            System.err.println(ex);
        }
        return null;
    }

    /**
     * Encrypts the message.
     *
     * @return The encrypted message.
     */
    private static byte[] encrypt(String decrypted) {
        try {
            cipher.init(Cipher.ENCRYPT_MODE, secretkeySpec);
            return cipher.doFinal(decrypted.getBytes());
        } catch (Exception ex) {
            System.err.println(ex);
        }
        return null;
    }

    /**
     * The constructor.
     */
    private AES() {
        try {
            cipher = Cipher.getInstance("AES");
            keyGenerator = KeyGenerator.getInstance("AES");
            keyGenerator.init(KEY_SIZE);
            secretKey = keyGenerator.generateKey();
            byte[] raw = secretKey.getEncoded();
            secretkeySpec = new SecretKeySpec(raw, "AES");
        } catch (NoSuchAlgorithmException ex) {
            System.err.println(ex);
        } catch (NoSuchPaddingException ex) {
            System.err.println(ex);
        }
    }

    /**
     * Runs the program.
     *
     * @param args
     *            The running arguments
     */
    public static void main(String[] args) {
        try {
            new AES();
            byte[] encrypted = encrypt(MESSAGE);
            System.out.println("Encrypted: " + encrypted);
            System.out.println("Decrypted: " + decrypt(encrypted));
        } catch (Exception ex) {
            System.err.println(ex);
        }
    }
}