public static SecretKey generateKey() throws NoSuchAlgorithmException {

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

    keyGen.init(128); // for example

    return keyGen.generateKey();

}

​

public static byte[] encryptMsg(String message, SecretKey secret) 

        throws NoSuchAlgorithmException, NoSuchPaddingException, 

        InvalidKeyException, InvalidParameterSpecException, 

        IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {

    Cipher cipher;

    cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");

    cipher.init(Cipher.ENCRYPT_MODE, secret);

    return cipher.doFinal(message.getBytes("UTF-8"));

}

​

public static String decryptMsg(byte[] cipherText, SecretKey secret) 

        throws NoSuchPaddingException, NoSuchAlgorithmException, 

        InvalidParameterSpecException, InvalidAlgorithmParameterException, 

        InvalidKeyException, BadPaddingException, IllegalBlockSizeException, UnsupportedEncodingException {

    Cipher cipher;

    cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");

    cipher.init(Cipher.DECRYPT_MODE, secret);

    return new String(cipher.doFinal(cipherText), "UTF-8");

}