Domain Key Authorities (DKA): DNS-Designated Public Key Distribution for Email-Address Identifiers

This document specifies the Domain Key Authority (DKA) framework, a DNS-anchored public-key distribution mechanism for the email-address namespace. The framework enables an Internet domain to designate an authoritative key service that verifies, stores, and distributes selector-scoped public keys for email-address identifiers under that domain. The result is a decentralized, deterministic, and application-agnostic framework for verified public-key discovery that supports incremental deployment and cryptographic agility.