From Byzantine fault tolerance to intrusion tolerance (a position paper)

A system is said intrusion-tolerant if it maintains its security properties despite some of its components being compromised by a malicious adversary. Although the implementation of these systems usually requires the use of Byzantine fault-tolerant (BFT) protocols, they are not a complete solution. Besides BFT replication, there are several other techniques such as proactive recovery, diversity and confidential operation that are needed to implement these systems. Many of these techniques present interesting open problems that need to be addressed before a complete intrusion-tolerant system could be build and deployed.