Detecting Relay Attacks with Timing-Based Protocols

Distance bounding protocols have been proposed as means of detecting relay attacks, also known as 'mafia fraud'. In this paper we present the first symmetric key based distance bounding protocol that is also resistant to so-called 'terrorist fraud', a variant of mafia fraud. Relay attacks present a serious threat to RF security devices (contactless smart cards, RFID tags and the like) because they undermine the implicit assumption that the device is physically close to the reader when it is operating. In applications such as physical access control this assumption of physical proximity is all-important. Distance bounding protocols require a communication channel that can exchange single bits with extremely low latency. This unconventional communication requirement has prompted Hancke and Kuhn to assert in a recent publication that ultra wide band (UWB) radio is necessary to achieve a useful distance bounding resolution. We analyse this assertion and present a alternative, novel communication approach that leverages the phenomena of side channel leakage to deliver a low latency channel. Our proposal is capable of detecting sophisticated relay attacks without resorting to the considerable expense and complexity of UWB radio. We present experimental results to support our arguments.