(2026-02) A Cryptographic Framework for Proof of Personhood
2026-02-20
We initiate study on how to build a rigorous, cryptographic foundation for proofs of personhood - convincing, privacy-preserving evidence that a digital participant is a real, unique, and reputable human, optionally with authenticated attributes such as age or institutional affiliation. Towards this goal, we introduce a framework based on two types of credentials: personhood credentials (PHCs), issued by trusted authorities to attest to uniqueness and basic attributes, and verifiable relationship credentials (VRCs), issued peer-to-peer to capture reputation and real-world interactions.
We formalize ideal functionalities that capture desirable security and privacy notions for proofs of personhood, including Sybil-resistance, authenticated personhood, and unlinkability across contexts. Finally, we then give efficient cryptographic constructions that realize these functionalities by combining PHCs, VRCs, and zero-knowledge proofs. Our results suggest that a scalable, Sybil-resistant, and decentralized proof-of-personhood layer can serve as a reusable trust substrate for a wide range of online economic, social, and civic applications.