A Low-Energy Key Management Protocol for Wireless Sensor Networks

*Abstract. Sensor networks have recently gained popularity for a wide spectrum of applications. When performing monitoring tasks in hostile environments, security requirements become critically important. Moreover, limited energy, computing, and memory resources prohibit the use of complex security mechanisms within sensor networks. Therefore, well balancing between security level and the associated energy consumption overhead becomes a must. In this paper, we concentrate on the key management aspect of the security functionality. Key management is essential for any cryptographic security system. We present an energy-aware approach for managing the cryptographic keys in a clustered sensor network. Shared symmetric keys are pre-deployed into the sensors and gateways (the cluster heads), requiring each sensor node to store only two secret keys. Separate protocols handle network bootstrapping, sensor addition/revocation, and key renewals. The protocols do not trust individual sensors, and partially trust the gateways. Eviction of compromised sensors and gateways are supported, although yet we do not present an intrusion detection mechanism. Simulation shows that the energy consumption overhead for the key management is remarkably low and reports an order-of-magnitude energy saving.