Secure Location Verification: Why You Want Your Verifiers to Be Mobile

The integrity of location information is crucial in many applications such as access control or environmental sensing. Although there are several solutions to the problem of secure location verification, they all come with expensive requirements such as tight time synchronization, cooperative verification protocols, or dedicated hardware. Yet, meeting these requirements in practice is often not feasible which renders the existing solutions unusable in many scenarios. We therefore propose a new solution which exploits the mobility of verifiers to verify locations. We show that mobility can help minimize system requirements while at the same time achieves strong security. Specifically, we show that two moving verifiers are sufficient to securely verify location claims of a static prover without the need for time synchronization, active protocols, or otherwise specialized hardware. We provide formal proof that our method is secure with minimal effort if the verifiers are able to adjust their movement to the claimed location (“controlled mobility”). For scenarios in which controlled mobility is not feasible, we evaluate how more general claim-independent movement patterns of verifiers affect the security of our system. Based on extensive simulations, we propose simple movement strategies which improve the attack detection rate up to 290% with only little additional effort compared to random (uncontrolled) movements.