The HotStuff Family and View Synchronization

Picks up where PBFT leaves off: HotStuff streamlined Byzantine SMR into a simple, linear, pipelined leader-based protocol achieving responsiveness and optimal communication per view. Covers Two-round HotStuff combined with SMR and accountability (identifying which party is to blame when something goes wrong), and an Information-Theoretic variant removing the need for a PKI entirely. View synchronization — getting all honest parties into the same view at (close to) the same time, via synchronized clocks and fixed view schedules — is the mechanism that makes leader rotation in these protocols actually work in practice. Surveys the broader family this line of work spawned: HotStuff-2’s relationship to PBFT/Tendermint/SBFT, Dfinity’s consensus protocols (in both synchrony and partial synchrony), Sandglass (safe permissionless consensus), HotStuff-1 and its prefix-speculation dilemma, Carry (HotStuff linearity with tail-forking resilience), and formal tools for comparing/verifying protocols in this family (smart casual verification, the pipes model for reasoning about latency and communication complexity together).

Outline (TODO — flesh out each)

• Two-round HotStuff with SMR and accountability
• Information-Theoretic HotStuff
• Synchronized clocks, fixed view schedules, and simultaneous agreement
• View synchronization
• HotStuff-2 and its relation to PBFT, Tendermint, SBFT
• Consensus by Dfinity — synchrony and partial synchrony
• Sandglass — safe permissionless consensus
• HotStuff-1 and the prefix speculation dilemma; Carry
• Smart casual verification; the pipes model