A Hybrid Key Management Protocol for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are wireless ad-hoc networks of tiny battery-operated wireless sensors. They are usually deployed in unsecured, open, and, harsh environments where it is difficult for humans to perform continuous monitoring. Due to its nature of deployment it is very crucial to provide security mechanisms for authenticating data. Key management is a pre-requisite for any security mechanism. Due to memory, computation, and communication constraints of sensor nodes, distribution and management of key in WSNs is a challenging task. Because of its lightweight feature, symmetric crypto-systems are a natural choice for key management in WSNs. However, they often fail to provide a good trade-off between resilience and storage. On the other hand, Public Key Infrastructure (PKI) is infeasible in WSNs because of its continuous availability of trusted third party and heavy computational requirements for certificate verification. Pairing-Based Cryptography (PBC) has paved a way for how parties can agree on keys without any interaction. It has relaxed the requirement of expensive certificate verification on PKI system. In this paper, we propose a new hybrid ID based non-interactive key management protocol for WSNs, which leverages the benefits from both symmetric key based cryptosystems and PBC by combining them together. The proposed protocol is very flexible and suits many applications. We also provide mechanisms for key refresh when the network changes.