Deterministic En-Route Filtering of False Reports: A Combinatorial Design Based Approach

Wireless sensor networks are an easy target for report fabrication attack, where compromised sensor nodes can be used by an adversary to flood the network with bogus/false reports. En-route filtering is a mechanism where intermediate forwarding nodes identify and drop false reports while they are being forwarded toward the sink. Most of the existing en-route filtering schemes are probabilistic, where sensor nodes in each cell share secret keys with a fixed probability with intermediate nodes. Thus, forwarded reports are verified probabilistically by intermediate nodes, because of which false reports can travel several hops before being dropped. Few deterministic en-route filtering schemes have also been proposed in the literature, but all such schemes require a source to send the reports through a fixed path to reach the sink. In this paper, we propose a novel deterministic en-route filtering scheme based on a combinatorial design to overcome the above-mentioned limitations of the existing schemes. The use of combinatorial design-based keys ensures direct communication between all the sensor nodes while maintaining low key storage overhead in the network. We provide a comprehensive analysis of the proposed scheme. The proposed scheme notably performs better than the existing schemes in terms of the expected filtering position of false reports. Furthermore, the proposed scheme improves data authenticity in the network and is more buoyant to selective forwarding and report disruption attacks.