Sub-Grid Based Key Vector Assignment: A Key Pre-Distribution Scheme for Distributed Sensor Networks

Security in sensor networks is more important than traditional networks as they are deployed in hostile environments and are more prone to capture. Trusted third party authentication schemes, public-key systems are not suitable owing to their high resource requirements. Key pre-distribution was introduced in [3] to solve this problem. Our scheme achieves identical connectivity compared to the random key pre distribution [4] using a less number of preloaded keys in each sensor node. The design of our scheme is motivated by the observation that at present most key pre-distribution schemes employ random mechanisms which use a large number of keys and are unsuitable for sensor networks. In this paper we extend the deterministic key pre-distribution scheme proposed by us in our earlier work [1], which is based on assigning keys to sensors by placing them on a grid. This approach has been further modified to use multiple mappings of keys to nodes. In each mapping every node gets distinct set of keys which it shares with different nodes. The key assignment is done such that, there will be keys in common between nodes in different sub-grids. After randomly being deployed, the nodes discover common keys, authenticate and communicate securely. The analysis and simulation results show that this scheme is able to achieve better security compared to the random schemes.