Public Key Directory - Key Transparency for the Fediverse
Summary
The article describes the Public Key Directory (PKD), a federated approach to key transparency for the Fediverse inspired by Certificate Transparency. It uses an append-only Merkle-tree log to record key events, enabling verifiable history, GDPR-friendly key erasure, and distributed trust without centralized authorities. It provides PHP client and server implementations and positions PKD as a foundation for extending key transparency to other systems.