EBFT: Efficient BFT Consensus Through Shortcut Replies

As the core building block of blockchain technology, Byzantine Fault Tolerance (BFT) consensus has gathered renewed attention during the past decade. A large number of BFT consensus protocols have been proposed since its inception in the 1980s, the best-known of which is Practical Byzantine Fault Tolerance (PBFT). Generally speaking, PBFT consists of two sub-protocols: normal-case protocol and view-change protocol. However, it requires $7 \delta$ for a client to commit a request in the normal case, where $\delta$ represents the actual network delay. If a request happens to go through the view change process, it will take additional $7 \delta$ for a client to commit a request. To reduce the consensus latency, we propose a novel BFT consensus protocol named EBFT, which introduces the shortcut replies to the consensus design. With these shortcut replies, EBFT reduces the normal-case latency and view-change latency to $5 \delta$ and $2 \delta$, respectively. Extensive experiments are conducted to evaluate EBFT, whose results demonstrate its effectiveness.