HB#: Increasing the Security and Efficiency of HB+

The innovative HB protocol of Juels and Weis [10] extends device authentication to low-cost RFID tags. However, despite the very simple on-tag computation there remain some practical problems with HB and despite an elegant proof of security against some limited active attacks, there is a simple man-in-the-middle attack due to Gilbert et al. [8]. In this paper we consider improvements to HB in terms of both security and practicality. We introduce a new protocol that we denote random-HB. This proposal avoids many practical drawbacks of HB, remains provably resistant to attacks in the model of Juels and Weis, and at the same time is provably resistant to a broader class of active attacks that includes the attack of [8]. We then describe an enhanced variant called HB which offers practical advantages over HB.