Abstract: This paper proposes a method for evaluating and analyzing the security of a proactive secret sharing system. Due to the difficulty in quantitatively estimating the adversary ability, the stochastic modeling techniques are used for depicting the relationships of the security to teh threshold, the time period and the behavior of adversary. Thus, the process of state transition from the secure state to the compromised state can be modeled as the Markov chain. With the state-transition diagram, the security probability of the system is obtained. Simulation experiment shows that te method has good feasibility and effectiveness. As a result, the threshold and the time period can be selected based on the quantitative method rather than on the empirical knowledge.

Key words: proactive secret sharing, mobile attack, intrusion rate, Markov chain, failture probability