Lightweight Key Renewals for Clustered Sensor Networks

In sensor networks, sensors are likely to be captured by attackers because they are usually deployed in an unprotected or even a hostile environment. If an adversarial compromises a sensor, he/she uses the keys from the compromised sensor to uncover the keys of others sensors. Therefore, it is very important to renew the keys of sensors in a proactive or reactive manner. Even though many group key renewal schemes have been proposed, they have some security flaws. First, they employ a single group key in a cluster so that the compromise of one sensor discloses the group key. Second, they evict the compromised nodes by updating the compromised keys with noncompromised keys. This eviction scheme is useless when the non-compromised keys are exhausted due to the increase of compromised nodes. In this paper, we propose a lightweight key renewal scheme, which evicts the compromised nodes clearly by reforming clusters excluding compromised nodes. Besides, in a cluster, each member employs a pairwise key for communication with its CH (Cluster Head) so that our scheme is tolerable against sensor compromise. Our simulation results prove that the proposed scheme is more tolerable against the compromise of sensors and it is more energy-saving than the group key renewal schemes.