Wireless sensor networks (WSNs) have become a motivating technology as it can be constructed without communication infrastructures. WSN operates in harsh environment; therefore information security in infrastructureless WSN is one of the most important challenges. WSN possess different network architectures. Cluster-based WSN architecture is found to be efficient with reduced transmission power and low energy consumption. To enhance the purpose of cluster based WSN, it is necessary to protect the communication within a cluster. This paper focuses on cluster-based key management scheme. Further in this paper, a mathematical model is used to securely share key among the communicating entities in a group. Moreover, the proposed scheme prevents impersonators from accessing any information exchanged within a group. Security analysis shows that proposed scheme maintain a good level of security. Performance evaluation illustrate that proposed scheme is performed with minimum computation and communication overhead.

Key words: Group key, intra cluster, authentication, interpolation, sensor network.