EPIC: Efficient Asynchronous BFT with Adaptive Security

Asynchronous BFT protocols such as HoneyBadgerBFT and BEAT are inherently robust against timing, performance, and denial-of-service attacks. The protocols, however, achieve static security, where the adversary needs to choose the set of corrupted replicas before the execution of the protocol. The situation is in contrast to that of most of existing BFT protocols (e.g., PBFT) which achieve adaptive security, where the adversary can choose to corrupt replicas at any moment during the execution of the protocol. We present EPIC, a novel and efficient asynchronous BFT protocol with adaptive security. Via a five-continent deployment on Amazon EC2, we show that EPIC is slightly slower for small and medium-sized networks than the most efficient asynchronous BFT protocols with static security. We also find as the number of replicas is smaller than 46, EPIC's throughput is stable, achieving peak throughput of 8,000 - 12,500 tx/sec using t2.medium VMs. When the network size grows larger, EPIC is not as efficient as those with static security, with throughput of 4,000 - 6,300 tx/sec.