License: Creative Commons Attribution 3.0 Unported license (CC BY 3.0)
When quoting this document, please refer to the following
DOI: 10.4230/LIPIcs.DISC.2020.45
URN: urn:nbn:de:0030-drops-131236
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Civit, Pierre ; Gilbert, Seth ; Gramoli, Vincent

Brief Announcement: Polygraph: Accountable Byzantine Agreement

LIPIcs-DISC-2020-45.pdf (0.4 MB)


In this paper, we introduce Polygraph, the first accountable Byzantine consensus algorithm. If among n users f < n/3 are malicious then it ensures consensus, otherwise it eventually detects malicious users that cause disagreement. Polygraph is appealing for blockchains as it allows to totally order blocks in a chain whenever possible, hence avoiding double spending and, otherwise, to punish at least n/3 malicious users when a fork occurs. This problem is more difficult than it first appears. Blockchains typically run in open networks whose delays are hard to predict, hence one cannot build upon synchronous techniques [Andreas Haeberlen et al., 2007; Vitalik Buterin and Virgil Griffith, 2019]. One may exploit cryptographic evidence of PBFT-like consensus [Miguel Castro and Barbara Liskov, 2002], however detecting equivocation would be insufficient. We show that it is impossible without extra logs of at least Ω(n) rounds [Pierre Civit et al., 2019]. Each round of Polygraph exchanges O(n²) messages.

BibTeX - Entry

  author =	{Pierre Civit and Seth Gilbert and Vincent Gramoli},
  title =	{{Brief Announcement: Polygraph: Accountable Byzantine Agreement}},
  booktitle =	{34th International Symposium on Distributed Computing (DISC 2020)},
  pages =	{45:1--45:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-168-9},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{179},
  editor =	{Hagit Attiya},
  publisher =	{Schloss Dagstuhl--Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-131236},
  doi =		{10.4230/LIPIcs.DISC.2020.45},
  annote =	{Keywords: Fault detection, cryptography, equivocation, consensus}

Keywords: Fault detection, cryptography, equivocation, consensus
Collection: 34th International Symposium on Distributed Computing (DISC 2020)
Issue Date: 2020
Date of publication: 07.10.2020

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