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Quadratic Asynchronous DKG from Plain Setup

Authors Ittai Abraham , Renas Bacho , Gilad Stern

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Subject Classification

ACM Subject Classification
  • Theory of computation → Distributed algorithms
Keywords
  • Asynchronous Network
  • Consensus
  • Distributed Key Generation
  • Leader Election

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Abstract

Asynchronous distributed key generation (ADKG) is a fundamental primitive for building threshold cryptosystems and fault-tolerant distributed protocols in adversarial network settings. A central objective in this line of work is to achieve ADKG with O(n²) communication and constant round complexity under minimal setup assumptions. Recent progress has led to subcubic-communication ADKG protocols under different trade-offs. Feng and Tang (CRYPTO 2025) presented an ADKG protocol with O(n²) communication and O(1) rounds, but at the cost of a cubic-communication setup phase in which each party posts a linear-sized public key on a public bulletin board. In contrast, Abraham et al. (PODC 2026) achieved an ADKG protocol with a standard setup phase, where each party posts only a constant-sized public key, but with O(n^{2+1/k}) communication and O(k) rounds for a tunable parameter k ≤ log{n}. These results leave open whether one can simultaneously obtain constant-round complexity and quadratic communication under a standard setup phase. 
In this work, we resolve this open problem by presenting the first ADKG protocol that achieves O(n²) communication and O(1) rounds while requiring only a standard setup phase in which each party posts a constant-sized public key on a public bulletin board. Our protocol is resilient to a strongly adaptive adversary corrupting up to f < n/3 parties and assumes only random oracles and secure erasures, both of which are also assumed by prior subcubic-communication ADKG constructions.

Cite As Get BibTex

Ittai Abraham, Renas Bacho, and Gilad Stern. Quadratic Asynchronous DKG from Plain Setup. In 40th International Symposium on Distributed Computing (DISC 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 397, pp. 9:1-9:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026) https://doi.org/10.4230/LIPIcs.DISC.2026.9

Author Details

Ittai Abraham
  • a16zcrypto, New York, NY, USA
Renas Bacho
  • Ruhr University Bochum, Germany
Gilad Stern
  • Tel Aviv University, Israel
  • Hebrew University, Jerusalem, Israel

Funding

  • Stern, Gilad: Gilad Stern is partially supported by the Israel Science Foundation (Grant No. 1336/22) and by the European Union (ERC, FTRC, 101043243). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them.

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