ETHPrague 2026

The web has a growing problem: it needs a better way to tell people apart from bots, and the current options are not holding up well. CAPTCHAs are increasingly fragile in the face of modern AI, while account-based authentication solves a different problem. It ties activity to an identity or account, but it does not actually prove personhood, and it often asks users to disclose more than a site really needs.
This talk is about X511, a protocol that turns HTTP 511 into a human-verification step. Rather than making users solve puzzles or create accounts, X511 lets them prove personhood through a mobile wallet that generates a zero-knowledge proof from an identity credential such as an ePassport. The site only learns the claim it needs, for example that the visitor is a real person or old enough to access a service, without learning their name, passport number, birth date, or other personal information.
We will cover how the protocol works end to end, how proof providers such as Self Protocol and ZK Passport fit into the flow, and how the reference implementation works as middleware. We will also look at the tradeoffs: where this model is stronger than CAPTCHA-based approaches, and where deployment, wallet support, and document availability still limit it.