Proactive Recovery in Intrusion-Tolerant System Based on TTCB

This paper proposes two proactive recovery mechanisms, i.e., periodic grouped proactive recovery and annular proactive recovery. The periodic grouped proactive recovery divides the replicas into groups and each group recover periodically in round. The annular proactive recovery adopts a kind of annular system structure and recovers the replicas dynamically. Although there are some differences between grouped proactive recovery and annular proactive recovery in system size, availability, and security, the results of simulation experiments show that two proactive recovery mechanisms both can improve the availability obviously.