Rethinking about Guessing Attacks

Although various past eorts have been made to character-ize and detect guessing attacks, there is no consensus on the de nition of guessing attacks. Such a lack of generic deni-tion makes it extremely dicult to evaluate the resilience of security protocols to guessing attacks. To overcome this hurdle, we seek a new denition in this paper to fully characterize the attacker's guessing capabili-ties (i.e., guessability). This provides a general framework to reason about guessing attacks in a symbolic setting, in-dependent of specic intruder models. We show how the framework can be used to analyze both passive and active guessing attacks