Paper 2017/573

Ouroboros Praos: An adaptively-secure, semi-synchronous proof-of-stake protocol

Bernardo David
Peter Gaži
Aggelos Kiayias
Alexander Russell
Abstract

We present ``Ouroboros Praos'', a proof-of-stake blockchain protocol that, for the first time, provides security against fully-adaptive corruption in the semi-synchronous setting: Specifically, the adversary can corrupt any participant of a dynamically evolving population of stakeholders at any moment so long as the stakeholder distribution maintains an honest majority of stake; furthermore, the protocol tolerates an adversarially-controlled message delivery delay unknown to protocol participants. To achieve these guarantees we formalize and realize in the universal composition setting a suitable form of forward secure digital signatures and a new type of verifiable random function that maintains unpredictability under malicious key generation. Our security proof develops a general combinatorial framework for the analysis of semi-synchronous blockchains that may be of independent interest. We prove our protocol secure under standard cryptographic assumptions in the random oracle model.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
A minor revision of an IACR publication in EUROCRYPT 2018
Keywords
blockchainconsensusproof of stake.
Contact author(s)
peter gazi @ iohk io
History
2023-04-27: last of 3 revisions
2017-06-14: received
See all versions
Short URL
https://ia.cr/2017/573
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2017/573,
      author = {Bernardo David and Peter Gaži and Aggelos Kiayias and Alexander Russell},
      title = {Ouroboros Praos: An adaptively-secure, semi-synchronous proof-of-stake protocol},
      howpublished = {Cryptology ePrint Archive, Paper 2017/573},
      year = {2017},
      note = {\url{https://eprint.iacr.org/2017/573}},
      url = {https://eprint.iacr.org/2017/573}
}
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