A Fair and Resilient Decentralized Clock Network for Transaction Ordering

Authors Andrei Constantinescu , Diana Ghinea , Lioba Heimbach , Zilin Wang, Roger Wattenhofer

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Author Details

Andrei Constantinescu
  • ETH Zürich, Switzerland
Diana Ghinea
  • ETH Zürich, Switzerland
Lioba Heimbach
  • ETH Zürich, Switzerland
Zilin Wang
  • ETH Zürich, Switzerland
Roger Wattenhofer
  • ETH Zürich, Switzerland

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Andrei Constantinescu, Diana Ghinea, Lioba Heimbach, Zilin Wang, and Roger Wattenhofer. A Fair and Resilient Decentralized Clock Network for Transaction Ordering. In 27th International Conference on Principles of Distributed Systems (OPODIS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 286, pp. 8:1-8:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


Traditional blockchain design gives miners or validators full control over transaction ordering, i.e., they can freely choose which transactions to include or exclude, as well as in which order. While not an issue initially, the emergence of decentralized finance has introduced new transaction order dependencies allowing parties in control of the ordering to make a profit by front-running others' transactions. In this work, we present the Decentralized Clock Network, a new approach for achieving fair transaction ordering. Users submit their transactions to the network’s clocks, which run an agreement protocol that provides each transaction with a timestamp of receipt which is then used to define the transactions' order. By separating agreement from ordering, our protocol is efficient and has a simpler design compared to other available solutions. Moreover, our protocol brings to the blockchain world the paradigm of asynchronous fallback, where the algorithm operates with stronger fairness guarantees during periods of synchronous use, switching to an asynchronous mode only during times of increased network delay.

Subject Classification

ACM Subject Classification
  • Theory of computation → Cryptographic protocols
  • Median Validity
  • Blockchain
  • Fair Ordering
  • Front-running Prevention
  • Miner Extractable Value


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