Two's Company, Three Is a Crowd: A Group-Admission Protocol for WSNs

Once a wireless sensor network (WSN) is stable and has been running for a while, sensors start to fail due to hardware problems, battery exhaustion or even due to their physical destruction. In any case, the administrator of the network may wish to replace the damaged nodes with new ones to reinforce the coverage area. In this paper we make use of an out of band channel (OOB) to bootstrap an authenticated symmetric key. The protocol ensures that the new sensor nodes are currently part of the region covered by the network before negotiating sensitive key material and making them a part of the system and its operations. We describe a novel approach to group admission for wireless sensor networks using an OOB secure channel and perform a security evaluation over this protocol.