EthereumZuri.ch 2024

Compressed to 0: The Silent Strings of Proof of Personhood
04-07, 12:05–12:25 (Europe/Zurich), Surge Stage

We would like to present our latest paper on an empirical study of Idena protocol (idena.io). The paper titled “Compressed to 0: The Silent Strings of Proof-of-Personhood" is co-authored by Puja Ohlhaver, me, the founder of Idena, and Paula Berman.

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4749892

The paper highlights the flaws of Proof-of-Personhood, which prompted the Idena protocol to pivot towards "sublinear identity staking”. The findings will undoubtedly serve as the foundation for the next generation protocols proposing Sybil-resistant and collusion-resistant forms of consensus.


Idena is an open-source Proof of Personhood blockchain. To gain the status of a unique identity or “human” in Idena, users synchronously participate in a series of consecutive validation ceremonies, progressively increasing their status to “human".

Validation ceremonies are scheduled in advance (15:00 UTC) every few weeks (“epoch”). In each validation ceremony, participants solve 6 FLIP (“Filter for Live Intelligent People”) puzzles within 2 minutes. A FLIP is a cognitive test, consisting of a series of photos generated by other participants that convey an intelligible human story in one configuration and are meaningless in another random configuration. FLIPS aim to be a reverse Turing test, verifying the presence of a human rather than a bot. The AI-resistance of Idena's FLIPS is achieved by employing open source AI to assist users in creating their FLIPs.

Founder of Idena

Puja Ohlhaver is a lawyer, innovator, and technologist. She is a member of the Getting Plurality Research Group at the Allen Lab for Democracy Renovation at Harvard. She is co-author with Glen Weyl and Vitalik Buterin of “Decentralized Society: Finding Web3’s Soul.” Her writing has been featured in the New York Times, Washington Post, Politico, and WIRED. She previously practiced law at Skadden, Arps and founded ClearPath Surgical, Inc., a women’s healthcare company.