In recent years, in order to provide secure communication between Radio Frequency Identification (RFID) users different RFID authentication protocols have been proposed. In this paper, we investigate weaknesses of two new-found RFID authentication protocols that proposed by Shi et al. and Liu et al. in 2014. The Ouafi-Phan privacy model is used for privacy analysis. We show that these two protocols have some weaknesses and could not provide the security and the privacy of RFID users. Furthermore, two improved protocols are proposed that eliminate existing weaknesses in Shi et al.’s and Liu et al.’s protocols.
RFID authentication protocols, security and privacy, NTRU, RFID systems