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DOI: 10.4230/LIPIcs.AFT.2025.12

How Much Public Randomness Do Modern Consensus Protocols Need?

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

Published in: LIPIcs, Volume 354, 7th Conference on Advances in Financial Technologies (AFT 2025)

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)

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@InProceedings{bonneau_et_al:LIPIcs.AFT.2025.12,
  author =	{Bonneau, Joseph and B\"{u}nz, Benedikt and Christ, Miranda and Efron, Yuval},
  title =	{{How Much Public Randomness Do Modern Consensus Protocols Need?}},
  booktitle =	{7th Conference on Advances in Financial Technologies (AFT 2025)},
  pages =	{12:1--12:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-400-0},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{354},
  editor =	{Avarikioti, Zeta and Christin, Nicolas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2025.12},
  URN =		{urn:nbn:de:0030-drops-247310},
  doi =		{10.4230/LIPIcs.AFT.2025.12},
  annote =	{Keywords: Consensus, Randomness Beacon}
}

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DOI: 10.4230/LIPIcs.ITCS.2025.23

Accumulation Without Homomorphism

Authors: Benedikt Bünz, Pratyush Mishra, Wilson Nguyen, and William Wang

Published in: LIPIcs, Volume 325, 16th Innovations in Theoretical Computer Science Conference (ITCS 2025)

Abstract

Accumulation schemes are a simple yet powerful primitive that enable highly efficient constructions of incrementally verifiable computation (IVC). Unfortunately, all prior accumulation schemes rely on homomorphic vector commitments whose security is based on public-key assumptions. It is an interesting open question to construct efficient accumulation schemes that avoid the need for such assumptions. In this paper, we answer this question affirmatively by constructing an accumulation scheme from non-homomorphic vector commitments which can be realized from solely symmetric-key assumptions (e.g., Merkle trees). We overcome the need for homomorphisms by instead performing spot-checks over error-correcting encodings of the committed vectors. Unlike prior accumulation schemes, our scheme only supports a bounded number of accumulation steps. We show that such bounded-depth accumulation still suffices to construct proof-carrying data (a generalization of IVC). We also demonstrate several optimizations to our PCD construction which greatly improve concrete efficiency.

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Benedikt Bünz, Pratyush Mishra, Wilson Nguyen, and William Wang. Accumulation Without Homomorphism. In 16th Innovations in Theoretical Computer Science Conference (ITCS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 325, pp. 23:1-23:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)

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@InProceedings{bunz_et_al:LIPIcs.ITCS.2025.23,
  author =	{B\"{u}nz, Benedikt and Mishra, Pratyush and Nguyen, Wilson and Wang, William},
  title =	{{Accumulation Without Homomorphism}},
  booktitle =	{16th Innovations in Theoretical Computer Science Conference (ITCS 2025)},
  pages =	{23:1--23:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-361-4},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{325},
  editor =	{Meka, Raghu},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2025.23},
  URN =		{urn:nbn:de:0030-drops-226510},
  doi =		{10.4230/LIPIcs.ITCS.2025.23},
  annote =	{Keywords: Proof-carrying data, incrementally verifiable computation, accumulation schemes}
}

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How Much Public Randomness Do Modern Consensus Protocols Need?

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Accumulation Without Homomorphism

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