Byzantine fault-tolerant deferred update replication

Replication is a well-established approach to increasing database availability. Many database replication protocols have been proposed for the crash-stop failure model, in which servers fail silently. Fewer database replication protocols have been proposed for the byzantine failure model, in which servers may fail arbitrarily. This paper considers deferred update replication, a popular database replication technique, under byzantine failures. The paper makes three contributions. First, it shows that making deferred update replication tolerate byzantine failures is quite simple. Second, the paper presents a byzantine-tolerant mechanism to execute read-only transactions at a single server. Third, we consider byzantine client attacks against deferred update replication and discuss effective countermeasures against these attacks.