OpenID Connect Authentication

Allow CAS to act as an OpenId Connect Provider (OP).

:information_source: Remember

OpenId Connect is a continuation of the OAuth protocol with some additional variations. If you enable OpenId Connect, you will have automatically enabled OAuth as well. Options and behaviors that are documented for the OAuth protocol support may apply here just the same.

Support is enabled by including the following dependency in the WAR overlay:



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<dependency>
    <groupId>org.apereo.cas</groupId>
    <artifactId>cas-server-support-oidc</artifactId>
    <version>${cas.version}</version>
</dependency>





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implementation "org.apereo.cas:cas-server-support-oidc:${project.'cas.version'}"





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dependencyManagement {
    imports {
        mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
    }
}

dependencies {
    implementation "org.apereo.cas:cas-server-support-oidc"
}





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dependencies {
    /*
        The following platform references should be included automatically and are listed here for reference only.

        implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
        implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
        
    */
    implementation "org.apereo.cas:cas-server-support-oidc"
}

To learn more about OpenId Connect, please review this guide.

The current implementation provides support for:

Endpoints

Field Description
/oidc/.well-known The discovery endpoint used to query for CAS OIDC configuration information and metadata.
/oidc/.well-known/openid-configuration Same as .well-known discovery endpoint.
/oidc/.well-known/webfinger WebFinger discovery endpoint
/oidc/jwks Contains the server’s public keys, which clients may use to verify the digital signatures of access tokens and ID tokens issued by CAS. Accepts an optional state query parameter to narrow down keys by their current state (i.e. current, previous, future).
/oidc/authorize Authorization requests are handled here.
/oidc/profile User profile requests are handled here.
/oidc/logout Logout requests are handled here.
/oidc/introspect Query CAS to detect the status of a given access token via introspection. This endpoint expects HTTP basic authentication with OIDC service client_id and client_secret associated as username and password.
/oidc/accessToken, /oidc/token Produces authorized access tokens.
/oidc/revoke Revoke access or refresh tokens. This endpoint expects HTTP basic authentication with OIDC service client_id and client_secret associated as username and password.
/oidc/register Register clients via the dynamic client registration protocol.
/oidc/initToken Obtain an initial master access token required for dynamic client registration when operating in PROTECTED mode.
/oidc/clientConfig Update or retrieve client application definitions, registered with the server.
:warning: Use Discovery

The above endpoints are not strictly defined in the OpenID Connect specification. The CAS software may choose to change URL endpoints at any point in time. Do NOT hardcode these endpoints in your application configuration. Instead, use the Dynamic Discovery endpoint and parse the discovery document to discover the endpoints.

Configuration

The following settings and properties are available from the CAS configuration catalog:

The configuration settings listed below are tagged as Required in the CAS configuration metadata. This flag indicates that the presence of the setting may be needed to activate or affect the behavior of the CAS feature and generally should be reviewed, possibly owned and adjusted. If the setting is assigned a default value, you do not need to strictly put the setting in your copy of the configuration, but should review it nonetheless to make sure it matches your deployment expectations.

The configuration settings listed below are tagged as Optional in the CAS configuration metadata. This flag indicates that the presence of the setting is not immediately necessary in the end-user CAS configuration, because a default value is assigned or the activation of the feature is not conditionally controlled by the setting value. In other words, you should only include this field in your configuration if you need to modify the default value or if you need to turn on the feature controlled by the setting.

Configuration Metadata

The collection of configuration properties listed in this section are automatically generated from the CAS source and components that contain the actual field definitions, types, descriptions, modules, etc. This metadata may not always be 100% accurate, or could be lacking details and sufficient explanations.

Be Selective

This section is meant as a guide only. Do NOT copy/paste the entire collection of settings into your CAS configuration; rather pick only the properties that you need. Do NOT enable settings unless you are certain of their purpose and do NOT copy settings into your configuration only to keep them as reference. All these ideas lead to upgrade headaches, maintenance nightmares and premature aging.

YAGNI

Note that for nearly ALL use cases, declaring and configuring properties listed here is sufficient. You should NOT have to explicitly massage a CAS XML/Java/etc configuration file to design an authentication handler, create attribute release policies, etc. CAS at runtime will auto-configure all required changes for you. If you are unsure about the meaning of a given CAS setting, do NOT turn it on without hesitation. Review the codebase or better yet, ask questions to clarify the intended behavior.

Naming Convention

Property names can be specified in very relaxed terms. For instance cas.someProperty, cas.some-property, cas.some_property are all valid names. While all forms are accepted by CAS, there are certain components (in CAS and other frameworks used) whose activation at runtime is conditional on a property value, where this property is required to have been specified in CAS configuration using kebab case. This is both true for properties that are owned by CAS as well as those that might be presented to the system via an external library or framework such as Spring Boot, etc.

:information_source: Note

When possible, properties should be stored in lower-case kebab format, such as cas.property-name=value. The only possible exception to this rule is when naming actuator endpoints; The name of the actuator endpoints (i.e. ssoSessions) MUST remain in camelCase mode.

Settings and properties that are controlled by the CAS platform directly always begin with the prefix cas. All other settings are controlled and provided to CAS via other underlying frameworks and may have their own schemas and syntax. BE CAREFUL with the distinction. Unrecognized properties are rejected by CAS and/or frameworks upon which CAS depends. This means if you somehow misspell a property definition or fail to adhere to the dot-notation syntax and such, your setting is entirely refused by CAS and likely the feature it controls will never be activated in the way you intend.

Validation

Configuration properties are automatically validated on CAS startup to report issues with configuration binding, specially if defined CAS settings cannot be recognized or validated by the configuration schema. Additional validation processes are also handled via Configuration Metadata and property migrations applied automatically on startup by Spring Boot and family.

Indexed Settings

CAS settings able to accept multiple values are typically documented with an index, such as cas.some.setting[0]=value. The index [0] is meant to be incremented by the adopter to allow for distinct multiple configuration blocks.

Sample Client Applications

Troubleshooting

To enable additional logging, configure the log4j configuration file to add the following levels:



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...
<Logger name="org.apereo.cas.oidc" level="debug" additivity="false">
    <AppenderRef ref="casConsole"/>
    <AppenderRef ref="casFile"/>
</Logger>
<Logger name="PROTOCOL_MESSAGE" level="debug" additivity="false">
    <AppenderRef ref="casConsole"/>
    <AppenderRef ref="casFile"/>
</Logger>
...