Building ToF Resiliency Into UWB-Based Secure Distance Bounding Protocols

Verification of the physical proximity of a communication party, together with authentication, is an important requirement for system security. For example, in contactless payments, the point-of-sale should verify that the card is legitimate and physically present. Different distance-bounding (DB) protocols have been proposed and extensively studied to verify the physical proximity of communication parties, and to allow a verifier to authenticate a prover and verify whether the prover is located within the expected vicinity. Vulnerability analysis of proposed DB protocols from different attack perspectives and resilience in terms of data exchange errors have been extensively studied over the years. However, resilience in terms of Time-of-Flight (ToF) errors is missing in literature. In this work, we experimentally analyze and prove how multipath, none-line-of-sight (NLOS), and propagation effects affect ToF estimations, affecting DB protocols’ resilience by increasing their false rejection rate (FRR). We propose and evaluate a timing threshold function to effectively identify and mitigate the errors introduced into ToF ranging by NLOS conditions to improve ToF resilience in DB protocols. Security considerations regarding our proposed threshold function are also presented in this paper.