Authena

Authena is a zero-knowledge protocol for personhood verification: it answers whether an address belongs to one real, unique person without exposing identity. It aggregates a user's activity across social platforms, off-chain accounts and existing credentials into a set of verifiable claims, and the user proves with zero knowledge that they meet a set of conditions, leaving the verifier with a pass or fail plus whatever fields were authorised for disclosure.

Credentials come from two sources: social accounts bound through a signature challenge, and off-chain accounts imported as verifiable credentials issued by third parties. Each verification writes a proof and an expiry to a contract, so a verifier can check validity on demand without a plaintext record. The protocol is permissionless for other projects, used to filter sybil addresses when distributing rewards, to enforce one claim per person, and to weight verified addresses. IRYS, Intuition, Union, Somnia, Caldera and Trusta run parts of their verification through it.