Proving your location without giving up your privacy

Although location-based applications have existed for several years, verifying the correctness of a user's claimed location is a challenge that has only recently gained attention in the research community. Existing architectures for the generation and verification of such location proofs have limited flexibility. For example, they do not support the proactive gathering of location proofs, where, at the time of acquiring a location proof, a user does not yet know for which application or service she will use this proof. Supporting proactive location proofs is challenging because these proofs might enable proof issuers to track a user or they might violate a user's location privacy by revealing more information about a user's location than strictly necessary to an application. We present six essential design goals that a flexible location proof architecture should meet. Furthermore, we introduce a location proof architecture that realizes our design goals and that includes user anonymity and location privacy as key design components, as opposed to previous proposals. Finally, we demonstrate how some of the design goals can be achieved by adopting proper cryptographic techniques.