I noticed most people focusing on making more complex ledgers capable of executing "smart" contracts and/or crypto-magically obscuring transaction details and such. And I think those projects are pretty cool, but I'd always wanted to attempt to do the opposite and implement the simplest decentralized ledger I possibly could given lessons learned from bitcoin. I think that's what cruzbit is. Anything that I thought wasn't strictly necessary in bitcoin, or was otherwise weird, I got rid of. I wanted the design to be conceptually simple and extremely developer-friendly. I finally had some personal time on my hands so I decided, why not.

And now cruzbit exists.

We present HotStuff, a leader-based Byzantine fault-tolerant replication protocol for the partially synchronous model.

Once network communication becomes synchronous, HotStuff enables a correct leader to drive the protocol to consensus at the pace of actual (vs. maximum) network delay--a property called responsiveness--and with communication complexity that is linear in the number of replicas. To our knowledge, HotStuff is the first partially synchronous BFT replication protocol exhibiting these combined properties. HotStuff is built around a novel framework that forms a bridge between classical BFT foundations and blockchains. It allows the expression of other known protocols (DLS, PBFT, Tendermint, Casper), and ours, in a common framework.

Our deployment of HotStuff over a network with over 100 replicas achieves throughput and latency comparable to that of BFT-SMaRt, while enjoying linear communication footprint during leader failover (vs. quadratic with BFT-SMaRt).

GNU Taler is an electronic payment system under development at Inria.