Abstract
An urgent demand of deploying BFT consensus (e.g., atomic broadcast) over the Internet is raised for implementing (permissioned) blockchain services. The deterministic synchronous protocols can be simple and fast in good network conditions, but are subject to denial-of-service (or even safety vulnerability) when synchrony assumption fails. Asynchronous protocols, on the contrary, are robust against the adversarial network, but are substantially more complicated and slower for the inherent use of randomness.
Facing the issues, optimistic asynchronous atomic broadcast (Kursawe-Shoup, 2002; Ramasamy-Cachin, 2005) was proposed to improve the normal-case performance of the slow asynchronous consensus. They run a deterministic fastlane if the network condition remains good, and can fall back to a fully asynchronous protocol via a pace-synchronization mechanism (analog to view-change with asynchronous securities) if the fastlane fails. Unfortunately, existing pace-synchronization directly uses a heavy tool of asynchronous multi-valued validated Byzantine agreement (MVBA). When such fallback frequently occurs in the fluctuating wide-area network setting, the benefits of adding fastlane can be eliminated.
We present Bolt-Dumbo Transformer (BDT), a generic framework for practical optimistic asynchronous atomic broadcast. At the core of BDT, we set forth a new fastlane abstraction that is simple and fast, while preparing honest parties to gracefully face potential fastlane failures caused by malicious leader or bad network. This enables a highly efficient pace-synchronization to handle fallback. The resulting design reduces a cumbersome MVBA to a variant of the conceptually simplest binary agreement only. Besides detailed security analyses, we also give concrete instantiations of our framework and implement them. Extensive experiments demonstrate that BDT can enjoy both the low latency of deterministic protocols (e.g., 2-chain version of HotStuff and the robustness of state-of-the-art asynchronous protocols in practice.
© 2022 ACM.
Facing the issues, optimistic asynchronous atomic broadcast (Kursawe-Shoup, 2002; Ramasamy-Cachin, 2005) was proposed to improve the normal-case performance of the slow asynchronous consensus. They run a deterministic fastlane if the network condition remains good, and can fall back to a fully asynchronous protocol via a pace-synchronization mechanism (analog to view-change with asynchronous securities) if the fastlane fails. Unfortunately, existing pace-synchronization directly uses a heavy tool of asynchronous multi-valued validated Byzantine agreement (MVBA). When such fallback frequently occurs in the fluctuating wide-area network setting, the benefits of adding fastlane can be eliminated.
We present Bolt-Dumbo Transformer (BDT), a generic framework for practical optimistic asynchronous atomic broadcast. At the core of BDT, we set forth a new fastlane abstraction that is simple and fast, while preparing honest parties to gracefully face potential fastlane failures caused by malicious leader or bad network. This enables a highly efficient pace-synchronization to handle fallback. The resulting design reduces a cumbersome MVBA to a variant of the conceptually simplest binary agreement only. Besides detailed security analyses, we also give concrete instantiations of our framework and implement them. Extensive experiments demonstrate that BDT can enjoy both the low latency of deterministic protocols (e.g., 2-chain version of HotStuff and the robustness of state-of-the-art asynchronous protocols in practice.
© 2022 ACM.
| Original language | English |
|---|---|
| Title of host publication | CCS '22 |
| Subtitle of host publication | Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security |
| Publisher | Association for Computing Machinery |
| Pages | 2159-2173 |
| Number of pages | 15 |
| ISBN (Print) | 978-1-4503-9450-5 |
| DOIs | |
| Publication status | Published - Nov 2022 |
| Externally published | Yes |
| Event | 28th ACM SIGSAC Conference on Computer and Communications Security (CCS 2022) - Hybrid , Los Angeles, United States Duration: 7 Nov 2022 → 11 Nov 2022 https://www.sigsac.org/ccs/CCS2022/ |
Publication series
| Name | Proceedings of the ACM Conference on Computer and Communications Security |
|---|---|
| ISSN (Print) | 1543-7221 |
Conference
| Conference | 28th ACM SIGSAC Conference on Computer and Communications Security (CCS 2022) |
|---|---|
| Place | United States |
| City | Los Angeles |
| Period | 7/11/22 → 11/11/22 |
| Internet address |
Funding
We would like to thank Vincent Gramoli and the anonymous reviewers for their valuable comments. Yuan is supported in part by National Key R&D Project of China under Grant 2022YFB2701600, NSFC under Grant 62102404 and the Youth Innovation Promotion Association CAS. Qiang and Zhenliang are supported in part by research gifts from Ethereum Foundation, Stellar Foundation, Protocol Labs, Algorand Foundation and The University of Sydney.
Research Keywords
- asynchronous consensus
- byzantine-fault tolerance
- optimsitic path