A Trust and Authentication Framework for Cross-Domain Agent-to-Agent Communications

AI-based agent-to-agent communication increasingly occurs across trust domains (e.g., between enterprises, service providers, SaaS platforms, and application third parties). While many agent protocols and platforms can provide transport security and local permission models, deployments lack a coherent, interoperable baseline for verifiable agent identity, credentialing, cross-domain authorisation, delegation, revocation, and auditability. This document defines an architectural framework for a cross-domain trust substrate for AI-based agent ecosystems. The framework is intended to be agent protocol-agnostic and to provide a consistent trust baseline that existing and emerging AI agent protocols can build upon.