Skip to main content

6 December 2021 - George Danezis


George Danezis



Narwhal and Tusk: A DAG-based Mempool and Efficient BFT Consensus



This talk presents the Narwhal mempool which separates the task of reliable transaction dissemination from transaction ordering, in high-performance Byzantine fault-tolerant quorum-based consensus. Narwhal tolerates an asynchronous network and maintains high performance despite failures. Narwhal is designed to easily scale-out using multiple workers at each validator, and we demonstrate that there is no foreseeable limit to the throughput achieved. Composing Narwhal with a partially synchronous consensus protocol (Narwhal-HotStuff) yields significantly better throughput even in the presence of faults or intermittent loss of liveness due to asynchrony. However, loss of liveness can result in higher latency. To achieve overall good performance when faults occur we further present Tusk, a zero-message overhead asynchronous consensus protocol, to work with Narwhal. Pre-print:



George Danezis is Professor of Security and Privacy Engineering at the Department of Computer Science of University College London, and Chief Scientist at Mysten Labs a new Blockchain infrastructure start-up. He has been working on anonymous communications, privacy enhancing technologies (PET), traffic analysis and peer-to-peer decentralized systems since 2000. He co-founded in 2018, and the team was acquired in 2019 to work on Facebook Novi and the Diem payment system until 2021. He has previously been a Researcher for Microsoft Research, Cambridge; a visiting fellow at K.U.Leuven (Belgium); and a research associate at the University of Cambridge (UK). He has been a technical advisor for a number of Blockchain and privacy technology companies including Nym Technologies, Vega Protocol, Celestia, Privitar and Spherical Defense.


Web page -


Full CV -