Formal Modelling of PBFT Consensus Algorithm in Event-B

The practical Byzantine Fault Tolerance (PBFT) is a classical consensus algorithm that has been widely applied in an alliance blockchain system to make all nodes agree certain transactions under the assumption proportion of no more than 1/3. It prevalent due its performance, simplicity, and claimed correctness. However, any vulnerability can lead significant loss finance because one change transaction results after execution. This paper proposes formal development method PBFT by horizontal refinement Event-B, which allows us manage complexity proof process factoring correctness into several steps. During PBFT, we have specified core mechanism like parameterized message types, primary node change, water-mark interval. Furthermore, present mechanical verification safety liveness properties model Rodin, be partially used check using tree algorithms.