Shrestha, NibeshKumar, MohanDuan, SiSi2019-03-152019-03-152019-02-25Nibesh Shrestha, Mohan Kumar, SiSi Duan, Revisiting hBFT: Speculative Byzantine Fault Tolerance with Minimum Cost, 2019, https://arxiv.org/abs/1902.08505http://hdl.handle.net/11603/13070FaB Paxos sets a lower bound of 5f + 1 replicas for any two-step consensus protocols tolerating f byzantine failures. Yet, hBFT promises a two-step consensus protocol with only 3f + 1 replicas. As a result, it violates safety property of a consensus protocol. In this note, we review the lower bound set by FaB Paxos and present a simple execution scenario that produces a safety violation in hBFT. To demonstrate the scenario, we require a relatively simple setup with only 4 replicas and one view-change.4 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.FaB Paxostwo-step byzantine fault tolerant consensus protocolhBFT protocolText