Secure top-k query processing in unattended tiered sensor networks

Many future large-scale unattended sensor networks (USNs) are expected to follow a two-tier architecture with resource-poor sensor nodes at the lower tier and fewer resource-rich master nodes at the upper tier. Master nodes collect data from sensor nodes and then answer the queries from the network owner on their behalf. In hostile environments, master and sensor nodes may be compromised by the adversary and return incorrect data in response to data queries. Such application-level attacks are more harmful and difficult to detect than blind denial-of-service attacks on network communications, particularly when the query results are the basis for critical decision making. This paper presents a suite of novel schemes to enable verifiable top-k query processing in USNs, which is the first work of its kind. The proposed schemes are built upon symmetric cryptographic primitives and enable the network owner to detect any incorrect top-k query results. Detailed theoretical and simulation results confirm the high efficacy and efficiency of the proposed schemes.