KEM-based Authentication for EDHOC in Initiator-Known Responder (IKR) Scenarios

This document specifies a more efficient variant of a Key Encapsulation Mechanism (KEM)-based authentication method for the Ephemeral Diffie-Hellman Over COSE (EDHOC) lightweight protocol, designed for the specific scenario in which the Initiator has prior knowledge of the Responder’s credentials, a case commonly found in constrained environments. Improving upon the approach described in KEM-based Authentication for EDHOC, this method uses only a mandatory three-message handshake to enable signature-free post-quantum authentication when PQC KEMs, such as the NIST-standardized ML-KEM, are employed, while still providing mutual authentication, forward secrecy, and a degree of identity protection.