Delegation

Table of Contents Introduction Why Token Exchange Exists The Core Concepts of RFC 8693 3.1 Actors and Roles 3.2 Grant Types and Token Types Protocol Flow in Detail 4.1 Step‑by‑Step Request/Response Walk‑through 4.2 Message Parameters Explained Practical Use‑Cases 5.1 Service‑to‑Service Delegation 5.2 Impersonation & On‑Behalf‑Of (OBO) 5.3 Cross‑Domain Identity Propagation 5.4 Legacy System Integration (SAML ↔ JWT) Implementing Token Exchange 6.1 Using Keycloak 6.2 Using Hydra (ORY) 6.3 Azure AD & Microsoft Identity Platform 6.4 Sample cURL & Python Code Security Considerations 7.1 Audience Restriction & Token Binding 7.2 Replay Protection & JTI 7.3 Scope Limiting & Principle of Least Privilege Common Pitfalls & Troubleshooting Future Directions & Extensions Conclusion Resources Introduction OAuth 2.0 has become the de‑facto standard for delegated authorization on the web. Its original grant types—authorization code, client credentials, resource owner password credentials, and implicit—address many classic scenarios, but modern micro‑service architectures, multi‑tenant SaaS platforms, and hybrid cloud‑on‑prem environments often demand more flexible token handling. ...

RFC 8693: Mastering OAuth 2.0 Token Exchange for Secure Delegation and Impersonation In the evolving landscape of modern web applications and microservices, securely managing identities across trust boundaries is paramount. RFC 8693, published in January 2020, defines the OAuth 2.0 Token Exchange protocol, providing a standardized HTTP- and JSON-based mechanism for clients to request and obtain security tokens from authorization servers acting as Security Token Services (STS).[1][3][4] This specification extends OAuth 2.0 to support critical patterns like impersonation and delegation, addressing gaps left by legacy protocols like WS-Trust.[1] ...