Sensor networks are composed of a large number of low power sensor devices. For secure communication among sensors, secret keys must be established between them. The establishment of secret keys after deployment of sensors requires wireless communication. Because of the energy constraints, an efficient key establishment scheme cannot be designed without considering the power consumption factor in wireless communication. In order to reduce the communication overhead, we propose a source routing based pairwise key establishment protocol for large-scale sensor networks. We then use a probability model proposed in [D. Huang et al., (2004)] to analyze the communication overhead, and security strength of the scheme.

Efficient schemes for key predistribution and shared-key discovery play a vital role in security and efficiency of pairwise key establishment in sensor networks. In this paper, we propose a scheme for key predistribution using hash-chain and subsequent shared-key discovery. We show potential active attacks on sensor networks due to key predistribution which can have severer consequences as compared to attacks described in existing proposals. We also show that as compared to the existing schemes, our scheme is more resilient to these active attacks.