Bi-directional RPROB-based Location Anonymizer System for Location-Based Services

We propose RBLA2, a Bi-directional RPROB-based Location Anonymizer system for location-based services. Our proposed system provides location privacy not only when users are forwarding requests to location-based services but also when these services deliver messages to the users using two similarly structured components that are based on a RPROB framework and global dummy generation. The system overcomes the imprecision of the query result and any inefficiencies due to a large number of candidates in the query result of the existing obfuscation or spatial cloaking techniques. Our system can guarantee the probabilistic-real-time property to deliver any request or response message within a maximum delay with a high probability using dummy generation. Our analysis and evaluation has shown that the system can guarantee location privacy for users against a global active adversary while providing low latency, which is an essential requirement in location-based services but cannot be satisfied when using general-purpose mix-net systems. Furthermore, the system also provides every user with the flexibility to define and update his/her own location privacy map.