keycloak-scim/docs/documentation/server_admin/topics/sso-protocols/con-oidc.adoc

[id="con-oidc_{context}"]

=== OpenID Connect
[role="_abstract"]
link:https://openid.net/developers/how-connect-works/[OpenID Connect] (OIDC) is an authentication protocol that is an extension of link:https://datatracker.ietf.org/doc/html/rfc6749[OAuth 2.0].

OAuth 2.0 is a framework for building authorization protocols and is incomplete. OIDC, however, is a full authentication and authorization protocol that uses the link:https://jwt.io[Json Web Token] (JWT) standards.  The JWT standards define an identity token JSON format and methods to digitally sign and encrypt data in a compact and web-friendly way.

In general, OIDC implements two use cases. The first case is an application requesting that a  {project_name} server authenticates a user. Upon successful login, the application receives an _identity token_ and an _access token_.
The _identity token_ contains user information including user name, email, and profile information. The realm digitally signs the _access token_ which contains access information (such as user role mappings) that applications use to determine the resources users can access in the application.

The second use case is a client accessing remote services.

* The client requests an _access token_ from {project_name} to invoke on remote services on behalf of the user.
* {project_name} authenticates the user and asks the user for consent to grant access to the requesting client.
* The client receives the _access token_ which is digitally signed by the realm.
* The client makes REST requests on remote services using the _access token_.
* The remote REST service extracts the _access token_.
* The remote REST service verifies the tokens signature.
* The remote REST service decides, based on access information within the token, to process or reject the request.