PAD: Privacy-area aware, dummy-based location privacy in mobile services

Location privacy in mobile services has the potential to become a serious concern for service providers and users. Existing privacy protection techniques that use k-anonymity convert an original query into an anonymous query that contains the locations of multiple users. Such techniques, however, generally fail in offering guaranteed large privacy regions at reasonable query processing costs. In this paper, we propose the PAD approach that is capable of offering privacy-region guarantees. To achieve this, PAD uses so-called dummy locations that are deliberately generated according to either a virtual grid or circle. These cover a user's actual location, and their spatial extents are controlled by the generation algorithms. The PAD approach only requires a lightweight server-side front-end in order for it to be integrated into an existing client/server mobile service system. In addition, query results are organized according to a compact format on the server, which not only reduces communication cost, but also facilitates the result refinement on the client side. An empirical study shows that our proposal is effective in terms of offering location privacy, and efficient in terms of computation and communication costs.