Verifiable fine-grained top-k queries in tiered sensor networks

Most large-scale sensor networks are expected to follow a two-tier architecture with resource-poor sensor nodes at the lower tier and 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 nodes may be compromised by the adversary and then instructed to return fake and/or incomplete data in response to data queries. Such application-level attacks are more harmful and difficult to detect than blind DoS attacks on network communications, especially when the query results are the basis for making critical decisions such as military actions. This paper presents three schemes whereby the network owner can verify the authenticity and completeness of fine-grained topk query results in tired sensor networks, which is the first work of its kind. The proposed schemes are built upon symmetric cryptographic primitives and force compromised master nodes to return both authentic and complete top-k query results to avoid being caught. Detailed theoretical and quantitative results confirm the high efficacy and efficiency of the proposed schemes.