A Hybrid RFID Protocol against Tracking Attacks

We study the problem how to construct an RFID mutual authentication protocol between tags and readers. Juels (in Journal on Selected Areas in Communications, 2006) proposed an open question which asks whether there exists a fully privacy-preserving RFID authentication protocol in which the time complexity of a successful authentication phase can be done in sub-linear time o(n) where n is the number of tags participating in the RFID system. In this work, we answer this question positively in an amortized view. Precisely, we design a fully privacy-preserving protocol in which the amortized cost of a successful authentication phase only requires time O(n^3/4). In addition, our protocol is a hybrid from the randomized hash lock scheme of Weis et. al., the hash chain scheme of Ohkubo et. al., and the efficient identification scheme of Dimitriou. We combine them delicately to obtain the desired authentication protocol.