With the wide application of radio frequency identification （RFID） technology, its security privacy issues are becoming more and more prominent. A RFID mutual-authentication protocol with synchronous updated-keys based on Hash function is proposed to tackle those problems in this paper. An updated mechanism of the dynamic tag keys is introduced and a self-synchronized scheme is designed in the protocol, which has achieved the second verification for the tags. The security of the protocol is verified and analyzed by the Burrows-Abadi-Needham （BAN） logic and the attack models, moreover it has been compared with the existing schemes o＇f security properties and its storage and computational performance. The results show that the proposed protocol has the ability to considerably reduce the amount of computation between tags and back-end database, and enhance the search efficiency of the whole system without the additional cost of the tags. It can satisfy safe requirements of RFID system effectively, also improve the authentication efficiency. The proposed protocol is more suitable for the low cost RFID system.
