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Documents authored by Choi, Kevin


Document
Accountable Secret Leader Election

Authors: Miranda Christ, Kevin Choi, Walter McKelvie, Joseph Bonneau, and Tal Malkin

Published in: LIPIcs, Volume 316, 6th Conference on Advances in Financial Technologies (AFT 2024)


Abstract
We consider the problem of secret leader election with accountability. Secret leader election protocols counter adaptive adversaries by keeping the identities of elected leaders secret until they choose to reveal themselves, but in existing protocols this means it is impossible to determine who was elected leader if they fail to act. This opens the door to undetectable withholding attacks, where leaders fail to act in order to slow the protocol or bias future elections in their favor. We formally define accountability (in weak and strong variants) for secret leader election protocols. We present three paradigms for adding accountability, using delay-based cryptography, enforced key revelation, or threshold committees, all of which ensure that after some time delay the result of the election becomes public. The paradigm can be chosen to balance trust assumptions, protocol efficiency, and the length of the delay before leaders are revealed. Along the way, we introduce several new cryptographic tools including re-randomizable timed commitments and timed VRFs.

Cite as

Miranda Christ, Kevin Choi, Walter McKelvie, Joseph Bonneau, and Tal Malkin. Accountable Secret Leader Election. In 6th Conference on Advances in Financial Technologies (AFT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 316, pp. 1:1-1:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{christ_et_al:LIPIcs.AFT.2024.1,
  author =	{Christ, Miranda and Choi, Kevin and McKelvie, Walter and Bonneau, Joseph and Malkin, Tal},
  title =	{{Accountable Secret Leader Election}},
  booktitle =	{6th Conference on Advances in Financial Technologies (AFT 2024)},
  pages =	{1:1--1:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-345-4},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{316},
  editor =	{B\"{o}hme, Rainer and Kiffer, Lucianna},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2024.1},
  URN =		{urn:nbn:de:0030-drops-209378},
  doi =		{10.4230/LIPIcs.AFT.2024.1},
  annote =	{Keywords: Consensus Protocols, Single Secret Leader Election, Accountability}
}
Document
Cornucopia: Distributed Randomness at Scale

Authors: Miranda Christ, Kevin Choi, and Joseph Bonneau

Published in: LIPIcs, Volume 316, 6th Conference on Advances in Financial Technologies (AFT 2024)


Abstract
We propose Cornucopia, a protocol framework for distributed randomness beacons combining accumulators and verifiable delay functions. Cornucopia generalizes the Unicorn protocol, using an accumulator to enable efficient verification by each participant that their contribution has been included. The output is unpredictable as long as at least one participant is honest, yielding a scalable distributed randomness beacon with strong security properties. Proving this approach secure requires developing a novel property of accumulators, insertion security, which we show is both necessary and sufficient for Cornucopia-style protocols. We show that not all accumulators are insertion-secure, then prove that common constructions (Merkle trees, RSA accumulators, and bilinear accumulators) are either naturally insertion-secure or can be made so with trivial modifications.

Cite as

Miranda Christ, Kevin Choi, and Joseph Bonneau. Cornucopia: Distributed Randomness at Scale. In 6th Conference on Advances in Financial Technologies (AFT 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 316, pp. 17:1-17:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


Copy BibTex To Clipboard

@InProceedings{christ_et_al:LIPIcs.AFT.2024.17,
  author =	{Christ, Miranda and Choi, Kevin and Bonneau, Joseph},
  title =	{{Cornucopia: Distributed Randomness at Scale}},
  booktitle =	{6th Conference on Advances in Financial Technologies (AFT 2024)},
  pages =	{17:1--17:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-345-4},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{316},
  editor =	{B\"{o}hme, Rainer and Kiffer, Lucianna},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.AFT.2024.17},
  URN =		{urn:nbn:de:0030-drops-209533},
  doi =		{10.4230/LIPIcs.AFT.2024.17},
  annote =	{Keywords: Randomness beacons, accumulators}
}
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