Universal Authenticated Sender Identity (UASI)

This document defines the Universal Authenticated Sender Identity (UASI) framework, a protocol-agnostic mechanism for cryptographic sender identity assertion and verification across Internet communication protocols. UASI provides a unified method by which any sending entity -- whether a mail server, an API endpoint, an IoT device, or a messaging service -- can assert its identity in a manner that receivers can independently verify using DNS-anchored trust. The framework is designed to be incrementally deployable, backwards-compatible with existing authentication mechanisms, and simple enough to encourage default-on adoption.