Detecting cheating aggregators and report dropping attacks in wireless sensor networks

This chapter focuses on an important, challenging and yet largely unaddressed problem in Wireless Sensor Networks (WSN) data communication: detecting cheating aggregators and malicious/selfish discarding of data reports en route to the Base Stations (BSs). If undetected, such attacks can significantly affect the performance of applications. The goal is to make the aggregation process tamper-resistant so that the aggregator cannot report arbitrary values, and to ensure that silent discarding of data reports by intermediate en-route nodes is detected in a bounded fashion. In our model, individual node readings are aggregated into data reports by Aggregator Nodes or Cluster Heads and forwarded to the BS. BS performs a two-stage analysis on these reports: (a) Verification through attached proofs, (b) Comparison with Proxy Reports for ensuring arrival accuracy. Proofs are non-interactive verifiers sent with reports to attest correctness of reported values. Proxy Reports are periodically sent along alternate paths by non-aggregator nodes, piggybacked on data reports from other nodes. The model is intended as a guide for implementing security in real sensor network applications. It is simple and comprehensive, covering a variety of data formats and aggregation models: numeric and non-numeric data and aggregators located across one or multiple hops. Security analysis shows that the reports, both primary and proxy, cannot be forged by any outsiders and the contents of the reports are held confidential and the scheme is robust against collusion attacks. Lightweight design aims at minimal additional control and energy overhead. Simulation results show its fault tolerance against random and patterned node failures.