Trusted hardware and new computing platforms such as RDMA naturally provide a non-equivocation abstraction. Previous works have shown that non-equivocation allows us to achieve tasks that otherwise would not have been possible in the plain model. In this paper, we are interested in understanding whether we can use non-equivocation to compile any asynchronous crash-fault protocol into one that tolerates the same number of Byzantine faults. Furthermore, we consider protocols with security and privacy guarantees that we must preserve under the compilation. Previous works have aimed to achieve a similar goal. However, we explain why the previous results in this area were incomplete. We then present a new compiler that achieves security and privacy, and does so while introducing only polynomial overhead over the underlying protocol (as compared to exponential overhead in previous results).

In the past five years or so, numerous blockchain projects have made tremendous progress towards improving permissioned consensus protocols (partly due to their promised applications in Proof-of-Stake cryptocurrencies). Although a significant leap has silently taken place in our understanding of consensus protocols, it is rather difficult to navigate this body of work, and knowledge of the new techniques appears scattered.