k-Strong Privacy for RFID Authentication Protocols Based on Physically Unclonable Functions

This paper examines Vaudenay’s privacy model, which is one of the first and most complete privacy models featured the notion of differen t privacy classes. We enhance this model by introducing two new generic adversa ry classes, k-strong andk-forward adversaries where the adversary is allowed to corrupt a tag at mostk times. Moreover, we introduce an extended privacy definition that also covers all privacy classes of Vaudenay’s model. In order to ac hieve highest privacy level, we study low cost primitives such as Physically Unclonable Functions (PUFs). The common assumption of PUFs is that their physical struc ture is destroyed once tampered. This assumption works only in the ideal case b ecause the tamper resistance depends on the ability of the attacker and the quality of the PUF circuits. In this paper, we have weaken this assumption by introduc ing a new definitionk-resistant PUFs . k-PUFs are tamper-resistant against at most k attacks, i.e., their physical structure remains still functional and corre t until at mostkth physical attack. Furthermore, we prove that strong privacy can be achieved without public-key cryptography using k-PUF based authentication. We finally prove that our extended proposal achieves both reader authen tication and k-strong privacy.