Abstract
Secure initialization of sensor nodes with cryptographic keys is inherent to all security protocols and applicationsin the area of wireless sensor networks (WSN).We introduce a general framework, denoted TOPKEY, thatprovides tool assistance and performs secure initialization ofsensor nodes with cryptographic keys over the air by leveraging the transmission power to confine the area in which potential attackers can eavesdrop on communication. Our analysis shows that physical protection based on transmission power may, inpractice, lead to an acceptable level of key deployment security. Besides the fully automated key deployment, TOPKEY supports a five-step initialization process, suited to off-the-shelf sensor nodes that come without any pre-installed operating system. TOPKEY is currently tailored to static WSN topologies: it supports topology design and deploys topology-driven key generation for a range of WSN communication patterns. We implemented the framework and analyzed its performanceand scalability for commodity TelosB nodes and Contiki OS. Our analysis, performed with respect to different WSN topologies, shows that TOPKEY can be used to securely initialize a static network of about 100 nodes in less than one minute.