code: public static String encrypt(String cleartext) {
  		if (cleartext != null) {
  			byte[] result = doFinal(Base64.decode(getBase64Key(), Base64.DEFAULT), Cipher.ENCRYPT_MODE,
  				cleartext.getBytes());
  			return Base64.encodeToString(result, Base64.DEFAULT);
  		}
  		return null;
  	}
docs: Returns the data encrypted. Avoid calling this method on the UI thread if possible, since it may access to shared
  preferences.
  
  @param cleartext
  @return encrypted data