Sybil Attacks on Inclusion List Mechanisms: FOCIL and AUCIL
2026-11-03 –, Lightning Stage

This talk will be about answering if Inclusion List Mechanisms can be made inherently Sybil proof, what the state of the art is when it comes to FOCIL and AUCIL and what may a Sybil proof design of an inclusion list mechanism do for Ethereum's censorship resistance.


Inclusion lists are important for Ethereum’s censorship resistance, but their robustness to Sybil attacks remains unresolved. This talk compares FOCIL and AUCIL under a false name attack model. FOCIL limits committee capture through sybils via stake based sampling, yet its economic guarantees can weaken when adversaries combine committee participation, bribery, and fake transactions (by Stouka et al.)
AUCIL raises censorship costs through a scoring auction design, but coordinated sybils may shift its Phase I equilibrium and manipulate the Phase II aggregation auction through multiple high scores. I will show how these attacks affect censorship cost, proposer incentives, and transaction inclusion, then examine mitigations such as stake based rewards, caps on marginal contribution, and optimization problems on committee sizing.
The talk concludes with design requirements for an inclusion list mechanism that remains censorship resistant even when one proposer controls many identities.

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Abhimanyu is a MITACS Fellow in Mathematics at the University of Alberta. He holds a BSc from the University of Alberta and has worked in Security, Risk and Consensus with Nethermind, Pantera Backed TanX, Catalysis Labs as well as Antler's Chainrisk Labs as Chief Scientist. His research has been published by IEEE, Springer, and Financial Cryptography, and he was cited in the Ethereum Research Paper at the age of 20 for EIP 5133. His main work is in the intersection of cryptography and economics.