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How Much Public Randomness Do Modern Consensus Protocols Need?

Authors Joseph Bonneau , Benedikt Bünz , Miranda Christ , Yuval Efron

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ACM Subject Classification
  • Theory of computation → Distributed algorithms
Keywords
  • Consensus
  • Randomness Beacon

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Abstract

Modern blockchain-based consensus protocols aim for efficiency (i.e., low communication and round complexity) while maintaining security against adaptive adversaries. These goals are usually achieved using a public randomness beacon to select roles for each participant. We examine to what extent this randomness is necessary. Specifically, we provide tight bounds on the amount of entropy a Byzantine Agreement protocol must consume from a beacon in order to enjoy efficiency and adaptive security. We first establish that no consensus protocol can simultaneously be efficient, be adaptively secure, and use O(log n) bits of beacon entropy. We then show this bound is tight and, in fact, a trilemma by presenting three consensus protocols that achieve any two of these three properties.

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Joseph Bonneau, Benedikt Bünz, Miranda Christ, and Yuval Efron. How Much Public Randomness Do Modern Consensus Protocols Need?. In 7th Conference on Advances in Financial Technologies (AFT 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 354, pp. 12:1-12:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025) https://doi.org/10.4230/LIPIcs.AFT.2025.12

Author Details

Joseph Bonneau
  • New York University, NY, USA
Benedikt Bünz
  • New York University, NY, USA
Miranda Christ
  • Columbia University, New York, NY, USA
Yuval Efron
  • Columbia University, New York, NY, USA

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