Asynchronous Byzantine fault-tolerant (BFT) protocols are arguably the most appropriate solutions for building high-assurance and intrusion-tolerant permissioned blockchains in wide-area (WAN) environments, as these asynchronous protocols are inherently more robust against timing and denial-of-service (DoS) attacks that can be mounted over an unprotected network such as the Internet. Asynchronous BFT ensures liveness of the protocol without depending on any timing assumptions, which is prudent when the network is controlled by an adversary. In contrast, partially synchronous BFT (e.g., PBFT) guarantees liveness only when the network becomes synchronous. For instance, it was shown in that PBFT would achieve zero throughput against an adversarial asynchronous scheduler.
In this talk, I will introduce BEAT, a set of practical BFT protocols for completely asynchronous environments. BEAT is flexible, versatile, and extensible, consisting of five asynchronous BFT protocols that are designed to meet different goals (e.g., different performance metrics, different application scenarios). Due to modularity in its design, features of these protocols can be mixed to achieve even more meaningful trade-offs between functionality and performance for various applications. Through a 92-instance, five-continent deployment of BEAT on Amazon EC2, we show that BEAT is efficient: roughly, all our BEAT instances significantly outperform, in terms of both latency and throughput, HoneyBadgerBFT, the most efficient asynchronous BFT prior to BEAT.
Dr. Haibin Zhang is an Assistant Professor in the Department of Computer Science and Electrical Engineering at University of Maryland, Baltimore County. He is interested in applied cryptography, security, privacy, distributed systems, and blockchains. He received the best paper candidate award at the 33rd IEEE International Symposium on Reliable Distributed Systems and proved the security of a NIST standard on ciphertext stealing. Haibin is one of the main inventors of Norton Zone, Symantec’s scalable cloud storage. Haibin is an inventor of three US patents.
Haibin has designed and implemented a number of blockchain consensus systems, including ByzID (SRDS 14, blockchain with trusted components), BChain (OPODIS 14, high-throughput blockchain), CBFT (SRDS 16, blockchain with confidentiality), causal BFT (DSN 17, blockchain with causality), and recently BEAT (CCS 18, asynchronous blockchain made practical). In particular, BChain has been implemented in Hyperledger Iroha, one of five mature platforms in Hyperledger, a global collaborative project under the Linux Foundation, now with nearly 300 members. BChain has been featured in more than 20 media outlets, and detailed in the Hyperledger whitepaper and Iroha document. Moreover, Haibin’s cryptographic works have been used in a number of open-source permissionless blockchain platforms such as OmniLedger (S&P 2018) and Mobius (PET 2018).