Key Recoverability in Wireless Sensor Networks

In case of an adversary that compromises a node in a wireless sensor network (WSN) and obtains its secret material, techniques for the detection of malicious or compromised nodes have been proposed in several papers. However, the ability to recover secure communications after a compromised node has been detected has not been thoroughly investigated. Such an ability allows to evaluate the level of proper functionality, i.e., the ratio of secure links in the network, that can be recovered after a successful attach and the withdrawal of the compromised secret material. This paper defines and discusses for the first time the recoverability property and provides the formulas to compute it for the main state-of-the-art key management schemes. All the formulas are validated through extensive simulation.