ATTP for Industrial Control Systems: Cryptographic Agent Authentication in SCADA and IoT Environments

This document defines an application profile of the Agent Trust Transport Protocol (ATTP) [draft-sharif-attp-agent-trust-transport] for use in Industrial Control Systems (ICS), Supervisory Control and Data Acquisition (SCADA) environments, and Internet of Things (IoT) deployments. It specifies how ATTP mandatory message signing, agent identity passports, and trust-gated access control apply to industrial protocols including Modbus/TCP, OPC UA, MQTT, and CoAP. The profile addresses the absence of per-message authentication in legacy industrial protocols, which has been exploited in numerous critical infrastructure attacks. It defines a gateway architecture that enables ATTP protection for legacy devices without firmware modification, maps ATTP trust levels to IEC 62443 Security Levels, and specifies real-time revocation mechanisms suitable for safety-critical environments.