Privacy of RFID systems is receiving increasing attention in the RFID community. Basically, there are two kinds of RFID privacy notions: one based on the indistinguishability of two tags, denoted as ind-privacy, and the other based on the unpredictability of the output of a protocol, denoted as unp-privacy. In this paper, the definition of unp-privacy is refined and the relation between the two notions is clarified: it is proven that ind-privacy is weaker than unp-privacy. Moreover, the minimal (necessary and sufficient) condition on RFID tags to achieve unp-privacy is determined. It is shown that if an RFID system has strong (or weak) unpprivacy then the computational power of an RFID tag can be used to construct a pseudorandom function family provided that the RFID system is complete and sound. On the other hand, if each tag is able to compute a pseudorandom function, then the tags can be used to construct an RFID system with strong (or weak) unp-privacy. In this sense, a pseudorand...
Changshe Ma, Yingjiu Li, Robert H. Deng, Tieyan Li