Forge Capsule

Byzantine Fault Tolerance: PBFT, Tendermint, and HotStuff

Byzantine fault tolerance (BFT): system functions correctly with up to f Byzantine nodes out of n=3f+1 total. PBFT (Castro-Liskov 1999): 3-phase protocol (pre-prepare, prepare, commit), O(n²) message complexity. Tendermint: round-based BFT with stake-weighted voting, used in Cosmos. HotStuff (Yin 2019): linear view-change, pipelined BFT, O(n) message complexity. Used in LibraBFT/DiemBFT (Facebook). SBFT: speculative BFT. Chained HotStuff: threshold signatures reduce overhead. Safety vs liveness tradeoff. Practical limits: n<100 validators for sub-second finality.