Solving the Simultaneous Scanning Problem Anonymously: Clumping Proofs for RFID Tags

The vast majority of works on RFID security focus only on privacy and tracking (violation of location privacy). However, in this paper we are interested in a new mechanism that enables a pair of RFID tags to generate a proof of having been simultaneously scanned by a reading device. In 2004, Juels introduced this concept and presented a proof named "yooking proof. Saito and Sakurai (2005) showed how Juels\´s proof was vulnerable to replay attacks, and proposed a new scheme based on using timestamps. Neverth less, Piramuthu later demonstrated that this new proof was also vulnerable to replay atacks. Although Piramthu\´sproposed scheme seems to be resistant to replay attacks, and attack using multi-proofs sessions can be attained. Furthermore, Piramuthu claims that privacy and location privacy is guaranteed in his scheme, which is not the case as tags transmit their static identifiers in clear. A new anon mous proof, named "clumping proof\´", is proposed here that solves the multi-proofs session attack and provides privacy while also protecting against tracking.