PBFTstyle

PBFTstyle refers to a class of Byzantine fault-tolerant consensus protocols whose design and operation are influenced by the Practical Byzantine Fault Tolerance (PBFT) protocol. Like PBFT, PBFTstyle protocols seek to enable a set of replicas to agree on a total order of client requests in the presence of faulty or malicious nodes, under partially synchronous network conditions. They are commonly used in permissioned or private deployments where a known set of validators participate.

In PBFTstyle systems, a designated leader coordinates rounds of voting, and progress is achieved through a sequence of phases in each consensus instance. A client request leads to the leader proposing an order, followed by backups issuing votes or certificates as the proposal is extended through the prepare and commit stages. A decision is made when a quorum, typically a supermajority, of matching votes or a threshold certificate is reached. To recover from a failed or malicious leader, the protocol performs a view change to elect a new leader and rebuilds progress from a newer view. Many PBFTstyle protocols also employ batching, pipelining, or threshold signatures to improve throughput and reduce latency.

Safety guarantees in PBFTstyle protocols ensure that once a decision is made, all correct replicas agree on the same order; this holds as long as fewer than one-third of replicas are Byzantine. Liveness requires some degree of synchrony or eventual synchrony in the network and timely view changes.

PBFTstyle has been influential in permissioned distributed ledgers and fault-tolerant databases, and has spawned various variants and optimizations that trade simplicity for performance, including reduced message complexity and enhanced fault detection.