Security analysis of centralized group key management schemes for wireless sensor networks under strong active outsider adversary model

Group Key Management is for maintaining a consistent group key that facilitates group communication in a dynamic group of members using a broadcast channel. Most group key management schemes preserve forward and backward secrecy of the group key under passive attack models. However, the more practical attack model is the strong active outsider adversary model. In this type of attack, an attacker can compromise one or more legitimate users as a result of which the secret key(s) of the compromised user is (are) also available to the adversary. In this paper, we select a class of group key management schemes for dynamic network of sensors that is centralized. We analyse them under the strong active adversary model and reason for their insecurity. We point that to make these schemes secure under strong active outsider attacks, number of updates required is linear in the number of nodes in the network which in turn is comparable to the cost of initial group set up.