Efficient Query Processing with Mutual Privacy Protection for Location-Based Services

Abstract

Data privacy in location-based services involves two aspects. The location of a user is a kind of private data as many sensitive information can be inferred from it given some background knowledge. On the other hand, the POI database is a great asset to the LBS provider as its construction requires many resources and efforts. In this paper, we propose a method of protecting mutual privacy i.e., the location of the user issuing a query and the POI database of the LBS provider for location-based query processing. Our approach consists of two steps: data preparation and query processing. Data preparation is conducted by LBS itself and is totally an offline computation, while query processing involves some online computation and multiple rounds of communication between LBS and the user. We implement the query processing by two rounds of oblivious transfer extension OT-Extension on two small key sets, resulting an immediate response even on some big POI databases. We also theoretically prove the security and analyze the complexity of our approach. Compared with two state-of-the-art methods, our approach has several orders of magnitude improvement in response time, at the expense of little and acceptable communication cost.