The RFID technology has been used by industries in recent years, for examples, replacing the traditional two-dimensional barcode, logistics management, military applications, identification. In fact, RFID technology has become one of the new killer technologies. The RFID uses radio frequency to convey information which involves, however, many security problems; Current RFID guidelines do not present solutions to these security problems. The methods put forward in published paper fail to offer complete solutions, either. This study identifies RFID security method for Entrance Guard system. The algorithms used include Hash, AES, random values, XOR four item technology, and use the three-way authentication structure to solve the safety problem...