Sensor networks are vulnerable to a variety of attacks because of the broadcast nature of wireless communications and the unattended operation in harsh environments. The well-established PKI-based key management schemes such as RSA are unfavorable due to the conflict between the extensive computation and large memory requirements, and the sensor node constraints and networking constraints. Symmetric key cryptography, on the other hand, is attractive and applicable to sensor networks due to its efficiency. Therefore establishing shared keys for communicating parties becomes a central problem for sensor network security research. Within the past few years, researchers proposed a number of probabilistic-based approaches relying on preloading keying information to each sensor for bootstrapping pairwise keys after deployment. However, the nondeterministic nature of all probabilistic-based schemes causes problems such as low scalability in network size and the unavoidable conflict between key-sharing probability and resilience against node capture attacks. This project intends to design truly in-situ key establishment schemes for large-scale sensor networks. Our algorithms require no keying information to be preloaded into regular worker sensors. A small number of sensors serve as service providers to facilitate the key establishment among worker sensors. This is a fundamentally different approach. Our preliminary research indicates that with low communication overhead and zero deployment knowledge our in-situ key establishment can achieve high scalability and resolve the conflict faced by probabilistic-based schemes. However, there are challenges that still need to be addressed in the context of in-situ key establishment, and we propose novel approaches to address these challenges. We also intend to systematically compare and contrast major existent key establishment schemes, and to study the geometric problems recasted by the sensor network security research. All outcomes will be infused into our KEYING SUITE, a library of keying mechanisms that will be open to the public to facilitate relevant research.
