Optimistic Agreement with Synchronous Fallback

We have designed a new byzantine agreement protocol and developed some theoretical upper and lower bounds on its performance and tolerance of malicious parties. Our consensus protocol functions by layering a fast asynchronous protocol on top of a slower, more reliable synchronous protocol. By doing this, we capture the speed of the async protocol while tolerating a higher number of malicious parties via the sync protocol. Compared to previous works, which are prone to slow restart times should the async protocol fail, our protocol is designed to obtain near-instantaneous restart times raising the bar on an adversarial network trying to slow down the system.