Key Management for Wireless Sensor Networks in Hostile Environments

Large-scale wireless sensor networks (WSNs) are highly vulnerable to attacks because they consist of numerous resource-constrained devices and communicate via wireless links. These vulnerabilities are exacerbated when WSNs have to operate unattended in a hostile environment, such as battlefields. In such an environment, an adversary poses a physical threat to all the sensor nodes. An adversary may capture any node, compromising critical security data including keys used for encryption and authentication. Consequently, it is necessary to provide security services to these networks to ensure their survival. We propose a novel, self-organizing key management scheme for large-scale and long-lived WSNs, called Survivable and Efficient Clustered Keying (SECK). SECK provides administrative services that ensures the survivability of the network. SECK is suitable for managing keys in a hierarchical WSN consisting of low-end sensor nodes clustered around more capable gateway nodes. Using cluster-based administrative keys, SECK provides five efficient security administration mechanisms: 1) clustering and key setup, 2) node addition, 3) key renewal, 4) recovery from multiple node captures, and 5) re-clustering. All of these mechanisms have been shown to localize the impact of attacks and considerably improve the efficiency of maintaining fresh session keys. Using simulation and analysis, we show that SECK is highly robust against node capture and key compromise while incurring low communication and storage overhead.