Achieving Sybil-Proofness in DistributedWork Systems

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In a multi-agent system where agents provide quantifiable work for each other on a voluntary basis, reputation mechanisms are incorporated to induce cooperation. Hereby agents assign their peers numerical scores based on their reported transaction histories. In such systems, adversaries can launch an attack by creating fake identities called Sybils, who report counterfeit transactions among one another, with the aim of increasing their own scores in the eyes of others. This paper provides new results about the Sybil-proofness of reputation mechanisms. We revisit the impossibility result of Seuken and Parkes (2011), who show that strongly-beneficial Sybil attacks cannot be prevented on reputation mechanisms satisfying three particular requirements. We prove that, under a more rigorous set of definitions of Sybil attack benefit, this result no longer holds. We characterise properties under which reputation mechanisms are susceptible to strongly-beneficial Sybil attacks. Building on our results, we propose a minimal set of requirements for reputation mechanisms to achieve resistance to such attacks, which are stronger than the results by Cheng and Friedman (2005), who show Sybil-proofness of certain asymmetric reputation mechanisms.
Original languageEnglish
Title of host publicationProceedings of the 20th International Conference on Autonomous Agents and MultiAgent Systems
Place of PublicationRichland, SC
PublisherInternational Foundation for Autonomous Agents and Multiagent Systems
Number of pages9
ISBN (Electronic)9781450383073
Publication statusPublished - 2021
Event20th International Conference on Autonomous Agentsand Multiagent Systems - Virtual/online event due to COVID-19
Duration: 3 May 20217 May 2021
Conference number: 20

Publication series

NameAAMAS '21
PublisherInternational Foundation for Autonomous Agents and Multiagent Systems
ISSN (Electronic)2523-5699


Conference20th International Conference on Autonomous Agentsand Multiagent Systems
Abbreviated titleAAMAS 2021


  • Sybil Attacks
  • Cooperation
  • Reputation
  • Impossibility Results


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