WORKERS AHEAD!

You are viewing the development documentation for the Apereo CAS server. The functionality presented here is not officially released yet. This is a work in progress and will be continually updated as development moves forward. You are most encouraged to test the changes presented.

Clients - OpenID Connect Authentication

Clients can be registered with CAS in the following ways.

Note that OpenID connect clients as service definitions are an extension of OAuth services in CAS. All settings that apply to an OAuth service definition should equally apply here as well.

Static Registration

OpenID Connect clients can be statically registered with CAS as such:

{
  "@class" : "org.apereo.cas.services.OidcRegisteredService",
  "clientId": "client",
  "clientSecret": "secret",
  "serviceId" : "^<https://the-redirect-uri>",
  "name": "OIDC",
  "id": 1000
}

Redirect URIs

Client application redirect URIs are specified using the serviceId field which supports regular expression patterns. If you need to support multiple URIs, you can try to OR them together or you may be able to construct the pattern that supports and matches all URIs with minor changes.

The following fields are specifically available for OpenID connect services:

Version	Reference
`clientId`	Required. The identifier for this client application.
`clientSecret`	Required. The secret for this client application. The client secret received from the service will be URL decoded before being compared to the secret in the CAS service definition.
`clientSecretExpiration`	Optional. Time, measured in UTC epoch, at which the `client_secret` will expire or 0 if it will not expire.
`serviceId`	Required. The authorized redirect URI for this OIDC client.
`supportedGrantTypes`	Optional. Collection of supported grant types for this service.
`supportedResponseTypes`	Optional. Collection of supported response types for this service.
`signIdToken`	Optional. Whether ID tokens should be signed. Default is `true`.
`jwks`	Optional. Resource path to the keystore location that holds the keys for this application.
`jwksKeyId`	Optional. JSON web key id to find in the keystore.
`jwksCacheDuration`	Optional. The expiration policy duration, i.e. `PT1S`, applied to loaded/cached keys for this application.
`encryptIdToken`	Optional. Whether ID tokens should be encrypted. Default is `false`.
`idTokenEncryptionOptional`	Optional. Whether ID tokens encryption should be skipped if no keystore or encryption key is available. Default is `false`.
`idTokenIssuer`	Optional. Override the `iss` claim in the ID Token, which should only be used in special circumstances. Do NOT use this setting carelessly as the ID token’s issuer MUST ALWAYS match the identity provider’s issuer.
`idTokenSigningAlg`	Optional. The algorithm header value used to sign the id token.
`idTokenEncryptionAlg`	Optional. The algorithm header value used to encrypt the id token.
`idTokenEncryptionEncoding`	Optional. The algorithm method header value used to encrypt the id token.
`userInfoSigningAlg`	Optional. The algorithm header value used to sign user profile responses.
`userInfoEncryptedResponseAlg`	Optional. The algorithm header value used to encrypt user profile responses.
`userInfoEncryptedResponseEncoding`	Optional. The algorithm method header value used to encrypt the user profile response.
`tokenEndpointAuthenticationMethod`	Optional. The requested client authentication method to the token endpoint.
`applicationType`	Optional. `web`, `native`, or blank. Defined the kind of the application. The default, if omitted, is `web`.
`subjectType`	Optional value chosen from `public` or `pairwise`. Type to use when generating principal identifiers. Default is `public`.
`sectorIdentifierUri`	Optional. Host value of this URL is used as the sector identifier for the pairwise identifier calculation. If left undefined, the host value of the `serviceId` will be used instead.

Keep What You Need!

You are encouraged to only keep and maintain properties and settings needed for a particular integration. It is UNNECESSARY to grab a copy of all service fields and try to configure them yet again based on their default. While you may wish to keep a copy as a reference, this strategy would ultimately lead to poor upgrades increasing chances of breaking changes and a messy deployment at that.

Service definitions are typically managed and registered with CAS by the service management facility.

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.}

cas.authn.oidc.services.defaults=

Control the default, initial values for fields that are part of a OIDC service definition. This is defined as a map where the key is the field name (i.e. signIdToken) and the value should be the default value. If a service definition explicitly defines a value for a field, that value will take over and the default defined here will be ignored. If a service definition does not define a value for a field and no defaults are specified for that field, then the default value that is directly assigned to the field in the body of the service definition will take over.

org.apereo.cas.configuration.model.support.oidc.OidcServicesProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

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.

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.authn.oidc.services.defaults=...

This is the most common form of property configuration that is recognized by CAS, regardless of the actual property source, which might in fact be managed separately outside the CAS environment, by another system or cloud framework.

CAS properties can be specified using the YAML syntax:

cas: 
  authn: 
    oidc: 
      services: 
        defaults: "..."

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.authn.oidc.services.defaults="..." -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory. Note the placement of the system property which must be specified before the CAS web application is launched.

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_AUTHN_OIDC_SERVICES_DEFAULTS="..."

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.authn.oidc.services.defaults="..."

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

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.

Note

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.

Example

An example registration record for an OpenID Connect relying party follows that allows the application with the redirect URI https://app.example.org/oidc to send authorization requests to CAS using the authorization code authentication flow. The registration record also instructs CAS to bypass the approval/consent screen and to assume access to requested scopes and claims should be granted automatically without the user’s explicit permission.

{
  "@class": "org.apereo.cas.services.OidcRegisteredService",
  "clientId": "client-id",
  "clientSecret": "secret",
  "serviceId": "^https://app.example.org/oidc",
  "name": "MyApplication",
  "id": 1,
  "bypassApprovalPrompt": true,
  "supportedResponseTypes": [ "java.util.HashSet", [ "code" ] ],
  "supportedGrantTypes": [ "java.util.HashSet", [ "authorization_code" ] ],
  "scopes" : [ "java.util.HashSet", [ "profile", "openid", "email" ] ]
}

Dynamic Registration

Client applications may dynamically be registered with CAS for authentication. See this guide for more info.