Sleep-wake protocols are critical in sensor networks to ensure long-lived operation. However, an open problem is how to develop efficient mechanisms that can be incorporated with sleep-wake protocols to ensure both longlived operation and a high degree of security. Our contribution in this paper is to address this problem by using local monitoring, a powerful technique for detecting and mitigating control/data attacks in sensor networks. In local monitoring, a node oversee part of the traffic going in and out of its neighbors to determine if the behavior is suspicious, such as, delay in forwarding a packet. However, a direct application of local monitoring will interfere with sleep-wake protocols by having nodes stay awake for the purpose of monitoring. In this work, we present a protocol called SLAM to make local monitoring parsimonious in its energy consumption and integrate it with any extant sleep-wake protocol in the network. The challenge is to enable this in a secure manner and this is addressed in the face of nodes that may be adversarial and not wake up nodes responsible for monitoring its traffic. We prove analytically that security coverage is not weakened by the sleeping. We perform simulation experiments to demonstrate that the performance of local monitoring is practically unchanged while listening energy savings of 30 to 129 times, depending on the network load, is achieved.

Date of this Version

November 2006