On optimal key disclosure interval for μTESLA: analysis of authentication delay versus network cost

μTESLA is a symmetric-key based broadcast authentication algorithm that periodically broadcasts key authentication packets in sensor networks with a key disclosure delay interval, T. Determining appropriate values for T is important to both performance and security. We analyze how to structure μTESLA to satisfy application imposed security and performance requirements while minimizing the network cost. The main contribution of the paper is a quantitative analysis of the optimal value of T such that the authentication broadcast cost is minimized while satisfying application imposed constraints on data authentication delay and packet rejection probability. We model the system using stochastic Petri nets. Our analysis results show that an optimal value of T exists and can be determined as a function of model parameter values characterizing the operating conditions.