Authentication of moving kNN queries

Man Lung Yiu, Eric Lo, Duncan Yung
2011 2011 IEEE 27th International Conference on Data Engineering  
A moving kNN query continuously reports the k nearest neighbors of a moving query point. In addition to the query result, a service provider that evaluates moving queries often returns mobile clients a safe region that bounds the validity of query results to minimize the communication cost between the two parties. However, when a service provider is not trustworthy, it may send inaccurate query results or incorrect safe regions to clients. In this paper, we present a framework and algorithms to
more » ... authenticate results and safe regions of moving kNN queries. Extensive experiments on both real and synthetic datasets show that our methods are efficient in terms of both computation time and communication costs. I. INTRODUCTION A moving kNN query [9, 25] continuously reports the k nearest neighbors of a moving query point q and it has numerous mobile applications, for example, finding the k nearest gas stations when a car moves or finding the k nearest restaurants when a tourist walks. Location-based service providers (LBS) that offer remote kNN querying services often return mobile users a safe region [9, 25] in addition to the query results. A safe region SR(q) of a moving query point q is a region in the dataset D where the results of query q remain unchanged as long as q moves within it. Safe region is a powerful optimization in moving query processing because it allows a mobile user to issue a new query to the LBS (to get the latest query results) only when the user leaves the safe region, thereby significantly reduces the communication frequency between the user and the service provider. Query results and safe regions returned by LBS, however, may not be always accurate. For instance, a hacker may have infiltrated the LBS's servers [20] so that results of kNN queries all include a particular location (e.g., the White House). Furthermore, it is possible that the LBS is self-compromised, and thus ranks sponsored facilities higher in its query results or returns overly large safe region to clients so as to save computation resources [12, 17, 24] . Recently, techniques for authenticating query results have received a lot of attention. For example, [6, 11, 21] study the authentication of relational queries; [7, 15] study the authentication of sliding window (data stream) queries; [12] addresses this issue on text similarity queries; [14, 22] study the authentication of static spatial queries; and [24] addresses the authentication of shortest path queries. The issue of authenticating moving queries, however, has not been addressed yet. Existing techniques for authenticating static spatial queries such as [14, 22] cannot help in authenticating moving queries because their authentication target is the query result, which
doi:10.1109/icde.2011.5767829 dblp:conf/icde/YiuLY11 fatcat:d6nmfu2ynzh6xjmjgqb5fp525e