public EncryptionKeys(
     @Nullable String adminKey, @Nullable String memberKey, @Nullable String guestKey) {
   _adminKey = getKeyFromString(adminKey);
   _memberKey = getKeyFromString(memberKey);
   _guestKey = getKeyFromString(guestKey);
   _adminKeyBytes = null;
   _memberKeyBytes = null;
   _guestKeyBytes = null;
   try {
     if (_adminKey != null) {
       _adminKeyBytes = BleUtils.hexStringToBytes(_adminKey);
     }
     if (_memberKey != null) {
       _memberKeyBytes = BleUtils.hexStringToBytes(_memberKey);
     }
     if (_guestKey != null) {
       _guestKeyBytes = BleUtils.hexStringToBytes(_guestKey);
     }
   } catch (java.lang.NumberFormatException e) {
     BleLog.getInstance().LOGe(TAG, "Invalid key format");
     e.printStackTrace();
   }
 }