Bullshark: DAG BFT Protocols Made Practical

We present BullShark, the first directed acyclic graph (DAG) based Byzantine Fault tolerant (BFT) protocol that is optimized for partial synchrony. BullShark inherits all the desired properties of its predecessor (DAG-Rider) such as optimal amortized complexity, asynchronous liveness, zero-overhead, and post-quantum safety, but at same time BullShark provides a practical low latency fast-path that exploits synchronous periods. In addition, we introduce a stand alone partially synchronous version of BullShark and evaluate it against the state of the art. The resulting protocol is embarrassingly simple (200 LOC on top of a DAG-based mempool implementation) and highly efficient, achieving for example, 125,000 transaction per second and 2 seconds latency with 50 nodes. ACM Reference Format: Neil Giridharan, Lefteris Kokoris-Kogias, Alberto Sonnino, and Alexander Spiegelman. 2022. Bullshark: DAG BFT Protocols Made Practical. In Proceedings of ACMConference, Los Angeles, CA, USA, November 2022 (Conference’22),

[1]  Marko Vukolic,et al.  Hyperledger fabric: a distributed operating system for permissioned blockchains , 2018, EuroSys.

[2]  Damian Lesniak,et al.  Aleph: Efficient Atomic Broadcast in Asynchronous Networks with Byzantine Nodes , 2019, AFT.

[3]  C. Stathakopoulou,et al.  Mir-BFT: High-Throughput BFT for Blockchains , 2019, ArXiv.

[4]  Dahlia Malkhi,et al.  Asynchronous Distributed Key Generation for Computationally-Secure Randomness, Consensus, and Threshold Signatures. , 2020, CCS.

[5]  Jing Xu,et al.  Dumbo: Faster Asynchronous BFT Protocols , 2020, IACR Cryptol. ePrint Arch..

[6]  Lei Yang,et al.  Prism: Scaling Bitcoin by 10, 000x , 2019, ArXiv.

[7]  Bryan Ford,et al.  Enhancing Bitcoin Security and Performance with Strong Consistency via Collective Signing , 2016, USENIX Security Symposium.

[8]  Aviv Zohar,et al.  Secure High-Rate Transaction Processing in Bitcoin , 2015, Financial Cryptography.

[9]  Ethan Buchman,et al.  Tendermint: Byzantine Fault Tolerance in the Age of Blockchains , 2016 .

[10]  Elaine Shi,et al.  Streamlet: Textbook Streamlined Blockchains , 2020, IACR Cryptol. ePrint Arch..

[11]  S. Bano,et al.  Twins: BFT Systems Made Robust , 2020, OPODIS.

[12]  Victor Shoup,et al.  Practical Threshold Signatures , 2000, EUROCRYPT.

[13]  Victor Shoup,et al.  Random Oracles in Constantinople: Practical Asynchronous Byzantine Agreement Using Cryptography , 2000, Journal of Cryptology.

[14]  Ittai Abraham,et al.  HotStuff: BFT Consensus with Linearity and Responsiveness , 2019, PODC.

[15]  Murat Demirbas,et al.  Bottlenecks in Blockchain Consensus Protocols , 2021, 2021 IEEE International Conference on Omni-Layer Intelligent Systems (COINS).

[16]  Tal Moran,et al.  Combining Asynchronous and Synchronous Byzantine Agreement: The Best of Both Worlds , 2018, IACR Cryptol. ePrint Arch..

[17]  Miguel Oom Temudo de Castro,et al.  Practical Byzantine fault tolerance , 1999, OSDI '99.

[18]  Moti Yung,et al.  Born and raised distributively: fully distributed non-interactive adaptively-secure threshold signatures with short shares , 2014, Theor. Comput. Sci..

[19]  Hovav Shacham,et al.  Short Signatures from the Weil Pairing , 2001, J. Cryptol..

[20]  George Danezis,et al.  Narwhal and Tusk: A DAG-based Mempool and Efficient BFT Consensus , 2021, ArXiv.

[21]  George Danezis,et al.  Embedding a Deterministic BFT Protocol in a Block DAG , 2021, PODC.

[22]  Nancy A. Lynch,et al.  Impossibility of distributed consensus with one faulty process , 1983, PODS '83.