Realization of RF Distance Bounding
Kasper Bonne Rasmussen, ETH Zurich
Distance bounding denotes a class of protocols in which one entity, the verifier, measures an upper bound on its distance to another (untrusted) entity, the prover. In recent years distance bounding has been extensively studied and it's use was suggested for secure localization, wormhole detection, key establishment and access control. Further more, distance bounding has been proposed for authentication through presence in the context of implanted medical devices. One of the main obstacles for the wider deployment of radio (RF) distance bounding is the lack of platforms that implement these protocols. In this work we present our recent progress in realizing radio distance bounding protocols. We present a protocol and a hardware platform that match the strict processing requirements of distance bounding and show that radio distance bounding protocols can indeed be implemented. Our system implements a prover that is able to receive, process and transmit radio signals in less than 1ns. The security guarantee that a distance bounding protocol built on top of this system therefore provides is that a malicious prover can, at most, pretend to be about 15cm closer to the verifier than it really is. We further show that functions such as XOR and the comparison function, that were used in a number of previously proposed distance bounding protocols, are not ideally suited for radio distance bounding due to the fact that they require interpretation (demodulation) of the signal within the time critical phase of the protocol. We managed the drastic reduction in processing time by introducing a new function that postpones the signal interpretation until after the time critical phase.