2. Pair-Wise Key Establishment

In this chapter we start addressing the security of Wireless Sensor Networks (WSNs) from the point of view which is closest to the single node: We consider the authentication and the confidentiality of the communications with other nodes. In particular, this chapter presents the ECCE Protocol, a new distributed, probabilistic, cooperative protocol to establish a secure pair-wise communication channel between any pair of sensors in a WSN. The main contribution of the ECCE Protocol is: To allow the set up of a secure channel between two sensors (principals) that do not share any pre-deployed key. This feature is obtained involving a set of sensors (cooperators) in the channel establishment protocol to provide probabilistic authentication of the principals as well as the cooperators. In particular, the probability for the attacker to break authentication check decreases exponentially with the number of cooperators involved. We provide analytical analysis and extensive simulations of the ECCE, which show that the proposed solution increases both the probability of a secure channel set up and the probability of channel resilience with respect to other protocols.