A Scalable Key Predistribution Scheme Based on Combinatorial Designs

The main requirement in Wireless Sensor Networks is not only security but energy efficient security due to limited resources. In large scale deployment scenarios, there is no priory knowledge of post deployment network configuration since nodes may be randomly scattered over a hostile territory. Thus, shared keys must be distributed before deployment to provide each node some keys. For large sensor networks it is infeasible to store a unique key for all other nodes in the keys of a sensor node. Consequently, for secure communication either two nodes have a key in common in their keys and they have a wireless link between them, or there is a path, among these two nodes where each pair of neighboring nodes on this path have a key in common. We review and examine the appropriateness of combinatorial designs as a tool for building key pre-distribution schemes suitable for such environments. A scalable key pre-distribution scheme based on combinatorial designs is presented. Performance and simulation results show that the combinatorial approach produces better connectivity with smaller key sizes. An important advantage of our scheme is that we can increase the scalability of the network.