Peer-to-Peer Presence Verification for Relationship-Bound Authorization

Existing protocols authenticate users to services, negotiate session keys, or protect message content from eavesdroppers. None verify that a remote party is the same individual whose key was accepted during an earlier in-person exchange and has just now physically authorized a signature on the device holding that key. Advances in synthetic media make it increasingly difficult to trust unauthenticated audio, video, or text for sensitive authorizations. This document defines transport-independent CBOR- and COSE-based objects that chain every remote interaction back to a bilateral in- person contact exchange -- not a certificate authority, identity provider, or key server. The protocol specifies Key Binding Objects, short-lived Session Credentials, replay-protected Signed Messages, a Presence Challenge requiring fresh platform-mediated user verification, and a Relationship Fingerprint for out-of-band key confirmation. It does not claim to prove biological humanness, legal identity, or voluntary action.