Witness-Based Location Proofs for Mobile Devices

Location-aware mobile applications are gaining popularity. This growth has caused the emergence of services that are offered to the users only when they are at specific locations. To implement valuable services, like a product sale, it is necessary to verify the presence of the user's device in a way which can be reliably trusted by the providers. This paper presents a system to support the creation of proofs that the user's device is at a claimed location. The system relies on different techniques for location estimation and on witness devices to testify to the presence of the user's device. A prototype was implemented and evaluated in regard to response times, accuracy of location estimates, and feasibility of proof exchanges. The results show that the solution is both practical and useful.