Client Registration - OAuth Authentication

Every OAuth relying party must be defined as a CAS service:

{
  "@class" : "org.apereo.cas.support.oauth.services.OAuthRegisteredService",
  "clientId": "clientid",
  "clientSecret": "clientSecret",
  "serviceId" : "^(https|imaps)://<redirect-uri>.*",
  "name" : "OAuthService",
  "id" : 100,
  "supportedGrantTypes": [ "java.util.HashSet", [ "...", "..." ] ],
  "supportedResponseTypes": [ "java.util.HashSet", [ "...", "..." ] ]
}

The following fields are supported:

Field	Description
`clientId`	The client identifier for the application/service.
`clientSecret`	The client secret for the application/service.
`supportedGrantTypes`	Collection of supported grant types for this service.
`supportedResponseTypes`	Collection of supported response types for this service.
`bypassApprovalPrompt`	Whether approval prompt/consent screen should be bypassed. Default is `false`.
`generateRefreshToken`	Whether a refresh token should be generated along with the access token. Default is `false`.
`renewRefreshToken`	Whether the existing refresh token should be expired and a new one generated (and sent along) whenever a new access token is requested (with `grant_type` = `refresh_token`). Only possible if `generateRefreshToken` is set to `true`. Default is `false`.
`jwtAccessToken`	Whether access tokens should be created as JWTs. Default is `false`.
`serviceId`	The pattern that authorizes the redirect URI(s), or same as `clientId` in case `redirect_uri` is not required by the grant type (i.e `client_credentials`, etc).

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 by the service management facility.

Usage Warning!

CAS today does not strictly enforce the collection of authorized supported response/grant types for backward compatibility reasons. This means that if left undefined, all grant and response types may be allowed by the service definition and related policies. Do please note that this behavior is subject to change in future releases and thus, it is strongly recommended that all authorized grant/response types for each profile be declared in the service definition immediately to avoid surprises in the future.

Encryptable Client Secrets

Client secrets for OAuth relying parties may be defined as encrypted values prefixed with {cas-cipher}:

{
  "@class": "org.apereo.cas.support.oauth.services.OAuthRegisteredService",
  "clientId": "clientid",
  "clientSecret": "{cas-cipher}eyJhbGciOiJIUzUxMiIs...",
  "serviceId" : "^(https|imaps)://<redirect-uri>.*",
  "name": "Sample",
  "id": 100
}

Client secrets may be encrypted using CAS-provided cipher operations either manually or via the CAS Command-line shell.

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. You should only include this field in your
configuration if you need to modify the default value.}

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.

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. The validation process is on by default and can be skipped on startup using a special system property SKIP_CONFIG_VALIDATION that should be set to true. 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.

Attribute Release

Attribute/claim filtering and release policies are defined per OAuth service. See this guide for more info.