docs: public static byte[] encryptAES(SecretKey key, byte[] iv, byte[] unencryptedBytes) throws
              NoSuchPaddingException, NoSuchAlgorithmException, InvalidAlgorithmParameterException,
              InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
          Cipher aesCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
          IvParameterSpec ivParameter = new IvParameterSpec(iv);
          // see http://stackoverflow.com/a/11506343
          Key encryptionKey = new SecretKeySpec(key.getEncoded(),"AES");
          aesCipher.init(Cipher.ENCRYPT_MODE, encryptionKey, ivParameter);
          return aesCipher.doFinal(unencryptedBytes);
      }