Security evaluation of proactive secret sharing cryptosystem

The proactive secret sharing (PSS) scheme divides the lifetime of a secret into a series of time periods, in which the shares are periodically updated without changing the secret. This paper proposes a practical method for evaluating and analyzing the security of PSS cryptosystem. Based on the response of server to the mobile attack, we apply the stochastic modeling techniques to depict the state transition of PSS cryptosystem, transferring from secure states to the compromised states. With the relationship of security to the threshold, the time period and the intrusion rate, an evaluation of security is obtained. The simulation figures show that the method is practical and applicable.