Securing top-k query processing in two-tiered sensor networks

Integrity and privacy are two important secure matrices in cyber security. Due to the limited resources and computing capability of the sensor nodes, it is challenging to simultaneously satisfy these two matrices for top-k querying in two-tiered sensor networks. To solve this problem, this paper proposes a weight-bind-based secure top-k query processing scheme (WBB-TQ), which utilises both the order-preserving symmetric encryption scheme (OPES) and the pairwise-key encryption technique to ensure data privacy in top-k querying. Since OPES can keep the size orders of the sensed data items unchanged before and after they are encrypted, the upper-layer storage nodes in the network can process top-k queries without knowing the exact values of the sensed data items. To guarantee the completeness of query results, we propose a novel method to establish chaining relationship among all the data items generated by each sensor node. By checking whether the relationship holds on not, Sink can find out whether adversaries drop and/or tamper with part or all of the qualified top-k data items in the query results. Theoretical analyses show that WBB-TQ can preserve data integrity and privacy of the top-k query results. Extensive simulation results further demonstrate that, WBB-TQ incurs very low computational and communication cost in securing top-k querying.