Authentication Flow Explained: Step-by-Step Login & Token Exchange Process

Modern authentication systems rely on a complex handshake between systems to ensure security without exposing user credentials, particularly through token-based identity. This approach separates apps from user credentials, allowing authorization servers to manage interactions with multiple identity providers. Key components include ID tokens and access tokens, which serve distinct roles, and the use of PKCE to secure single-page and mobile apps against potential attacks. JSON Web Tokens (JWTs) contain a header, payload, and signature, ensuring data integrity and authenticity, while token exchange and the On-Behalf-Of flow facilitate secure communication between services. Best practices for maintaining security include using refresh tokens, careful management of redirect URIs, and avoiding the storage of sensitive data in insecure locations. Enterprise systems are advised against in-house authentication solutions in favor of leveraging established identity providers to minimize security risks and focus on core business functionalities.