Mapping Claims - OpenID Connect Authentication

Claims associated with a scope (i.e. given_name for profile) are fixed in the OpenID specification. In the event that custom arbitrary attributes should be mapped to claims, mappings can be defined in CAS settings to link a CAS-defined attribute to a fixed given scope. For instance, CAS configuration may allow the value of the attribute sys_given_name to be mapped and assigned to the claim given_name without having an impact on the attribute resolution configuration and all other CAS-enabled applications.

If mapping is not defined, by default CAS attributes are expected to match claim names.

Claim mapping rules that are defined in CAS settings are global and apply to all applications and requests. Once a claim is mapped to an attribute (i.e. preferred_username to uid), this mapping rule will take over all claim processing rules and conditions.

Mapping Claims Per Service

Claim mapping rules may also be defined for each application using the rules described below:

  • The configuration below will allow CAS to map the value of the uid attribute to the preferred_username claim that is constructed in response to an authentication request from application Sample. The claim mapping rule here is exclusive to this application only, and does not affect any other application or global mapping rule, if any.

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    {
  "@class": "org.apereo.cas.services.OidcRegisteredService",
  "clientId": "client",
  "clientSecret": "secret",
  "serviceId": "^https://...",
  "name": "Sample",
  "id": 1,
  "scopes" : [ "java.util.HashSet", [ "openid", "profile" ] ],
  "attributeReleasePolicy": {
    "@class": "org.apereo.cas.oidc.claims.OidcProfileScopeAttributeReleasePolicy",
    "claimMappings" : {
      "@class" : "java.util.TreeMap",
      "preferred_username" : "uid"
    }
  }
}

  • The configuration below will allow CAS to map the value of the entitlements claim to the outcome of the inline Groovy script, when processing the rules for the MyCustomScope scope.

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    {
  "@class": "org.apereo.cas.services.OidcRegisteredService",
  "clientId": "client",
  "clientSecret": "secret",
  "serviceId": "^https://...",
  "name": "Sample",
  "id": 1,
  "scopes" : [ "java.util.HashSet", [ "openid", "profile", "MyCustomScope" ] ],
  "attributeReleasePolicy": {
    "@class": "org.apereo.cas.services.ChainingAttributeReleasePolicy",
    "policies": [
      "java.util.ArrayList",
      [
        {
          "@class": "org.apereo.cas.oidc.claims.OidcCustomScopeAttributeReleasePolicy",
          "order": 1,
          "scopeName": "MyCustomScope",
          "allowedAttributes" : [ "java.util.ArrayList", [ "entitlements" ] ],
          "claimMappings" : {
            "@class" : "java.util.TreeMap",
            "entitlements" : "groovy { return ['A', 'B'] }"
          }
        }
      ]
    ]
  }
}

    The inline script receives the following parameters for its execution:

    Policy Description
    context Attribute release execution context that carries references to the principal, registered service, etc.
    attributes Map of attributes that are currently resolved.
    logger The object responsible for issuing log messages such as logger.info(...).

    Note that the outcome of the script execution must be a List of a values.

Releasing Claims

Please see this guide to learn more.

Pairwise Identifiers

When pairwise subject type is used, CAS will calculate a unique sub value for each sector identifier. This identifier should not be reversible by any party other than CAS and is somewhat akin to CAS generating persistent anonymous user identifiers. Each value provided to every relying party is different so as not to enable clients to correlate the user’s activities without permission.

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{
  "@class" : "org.apereo.cas.services.OidcRegisteredService",
  "clientId": "client",
  "clientSecret": "secret",
  "serviceId" : "^<https://the-redirect-uri>",
  "subjectType": "pairwise",
  "usernameAttributeProvider" : {
    "@class" : "org.apereo.cas.services.PairwiseOidcRegisteredServiceUsernameAttributeProvider",
    "persistentIdGenerator" : {
      "@class" : "org.apereo.cas.authentication.principal.OidcPairwisePersistentIdGenerator",
      "salt" : "aGVsbG93b3JsZA=="
    }
  }
}

Subject Identifier Claim

To control and modify the value of the sub claim for each OpenID Connect relying party, you may change the application definition to return an attribute that is already resolved for the principal as the sub claim value for this service.

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{
  "@class" : "org.apereo.cas.services.OidcRegisteredService",
  "clientId": "client",
  "clientSecret": "secret",
  "serviceId" : "^<https://the-redirect-uri>",
  "scopes" : [ "java.util.HashSet", [ "openid", "profile" ] ]
  "usernameAttributeProvider" : {
    "@class" : "org.apereo.cas.services.PrincipalAttributeRegisteredServiceUsernameProvider",
    "usernameAttribute" : "cn"
  }
}

In general, all other constructs available to CAS that are described here which control the principal identifier that is shared with a client application may also be used to control the sub claim.