code: private static String getBase64Key() {
  		if (base64Key == null) {
  			base64Key = SharedPreferencesHelper.get().loadPreference(BASE64_KEY);
  			if (base64Key == null) {
  				base64Key = generateBase64Key();
  				SharedPreferencesHelper.get().savePreference(BASE64_KEY, base64Key);
  			}
  		}
  		return base64Key;
  	}
docs: Returns the encryption key stored on {@link SharedPreferences}. If the key is already on memory, it doesn't access the file system.
  You shouldn't call this method in the UI thread.