REST - SAML2 Metadata Management

Similar to the Dynamic Metadata Query Protocol (MDQ), SAML service provider metadata may also be fetched using a more traditional REST interface. This is a simpler option that does not require one to deploy a compliant MDQ server and provides the flexibility of producing SP metadata using any programming language or framework.

Support is enabled by including the following module in the overlay:

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<dependency>
    <groupId>org.apereo.cas</groupId>
    <artifactId>cas-server-support-saml-idp-metadata-rest</artifactId>
    <version>${cas.version}</version>
</dependency>
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implementation "org.apereo.cas:cas-server-support-saml-idp-metadata-rest:${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-saml-idp-metadata-rest"
}
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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-saml-idp-metadata-rest"
}

Use the below snippet as an example to fetch metadata from REST endpoints:

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{
  "@class" : "org.apereo.cas.support.saml.services.SamlRegisteredService",
  "serviceId" : "the-entity-id-of-the-sp",
  "name" : "SAMLService",
  "id" : 10000003,
  "evaluationOrder" : 10,
  "metadataLocation" : "rest://"
}
:information_source: Metadata Location

The metadata location in the registration record above needs to be specified as rest:// to signal to CAS that SAML metadata for registered service provider must be fetched from REST endpoints defined in CAS configuration.

Requests are submitted to REST endpoints with entityId as the parameter and Content-Type: application/xml as the header. Upon a successful 200 - OK response status, CAS expects the body of the HTTP response to match the below snippet:

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{  
   "id":1000,
   "name":"SAML Metadata For Service Provider",
   "value":"...",
   "signature":"..."
}

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.

  • cas.authn.saml-idp.metadata.rest.crypto.encryption.key=
  • The encryption key is a JWT whose length is defined by the encryption key size setting.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.signing.key=
  • The signing key is a JWT whose length is defined by the signing key size setting.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.url=
  • The endpoint URL to contact and retrieve attributes.

    org.apereo.cas.configuration.model.support.saml.idp.metadata.RestSamlMetadataProperties.

    How can I configure this property?

    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.saml-idp.metadata.rest.crypto.alg=
  • The signing/encryption algorithm to use.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.enabled=true
  • Whether crypto operations are enabled.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.encryption.key-size=512
  • The encryption key size.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.signing.key-size=512
  • The signing key size.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.strategy-type=ENCRYPT_AND_SIGN
  • Control the cipher sequence of operations. The accepted values are:

    • ENCRYPT_AND_SIGN: Encrypt the value first, and then sign.
    • SIGN_AND_ENCRYPT: Sign the value first, and then encrypt.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.basic-auth-password=
  • If REST endpoint is protected via basic authentication, specify the password for authentication.

    org.apereo.cas.configuration.model.support.saml.idp.metadata.RestSamlMetadataProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.basic-auth-username=
  • If REST endpoint is protected via basic authentication, specify the username for authentication.

    org.apereo.cas.configuration.model.support.saml.idp.metadata.RestSamlMetadataProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.headers=
  • Headers, defined as a Map, to include in the request when making the REST call. Will overwrite any header that CAS is pre-defined to send and include in the request. Key in the map should be the header name and the value in the map should be the header value.

    org.apereo.cas.configuration.model.support.saml.idp.metadata.RestSamlMetadataProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.idp-metadata-enabled=false
  • Whether identity provider metadata artifacts are expected to be found in the database.

    org.apereo.cas.configuration.model.support.saml.idp.metadata.RestSamlMetadataProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.method=GET
  • HTTP method to use when contacting the rest endpoint. Examples include GET, POST, etc.

    org.apereo.cas.configuration.model.support.saml.idp.metadata.RestSamlMetadataProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.encryption.key=
  • The encryption key is a JWT whose length is defined by the encryption key size setting.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.signing.key=
  • The signing key is a JWT whose length is defined by the signing key size setting.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.alg=
  • The signing/encryption algorithm to use.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.enabled=true
  • Whether crypto operations are enabled.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.encryption.key-size=512
  • The encryption key size.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.signing.key-size=512
  • The signing key size.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.saml-idp.metadata.rest.crypto.strategy-type=ENCRYPT_AND_SIGN
  • Control the cipher sequence of operations. The accepted values are:

    • ENCRYPT_AND_SIGN: Encrypt the value first, and then sign.
    • SIGN_AND_ENCRYPT: Sign the value first, and then encrypt.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

    This CAS feature is able to accept signing and encryption crypto keys. In most scenarios if keys are not provided, CAS will auto-generate them. The following instructions apply if you wish to manually and beforehand create the signing and encryption keys.

    Note that if you are asked to create a JWK of a certain size for the key, you are to use the following set of commands to generate the token:

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    wget https://raw.githubusercontent.com/apereo/cas/master/etc/jwk-gen.jar
    java -jar jwk-gen.jar -t oct -s [size]
    

    The outcome would be similar to:

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    {
      "kty": "oct",
      "kid": "...",
      "k": "..."
    }
    

    The generated value for k needs to be assigned to the relevant CAS settings. Note that keys generated via the above algorithm are processed by CAS using the Advanced Encryption Standard (AES) algorithm which is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology.


    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.

    Identity Provider Metadata

    Metadata artifacts that belong to CAS as a SAML2 identity provider may also be managed and stored via REST APIs. Artifacts such as the metadata, signing and encryption keys, etc are passed along to an external API endpoint in the following structure as the request body:

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    {
        "signingCertificate": "...",
        "signingKey": "...",
        "encryptionCertificate": "...",
        "encryptionKey": "...",
        "metadata": "...",
        "appliesTo": "CAS"
    }
    

    The URL endpoint, defined in CAS settings is expected to be available at a path that ends in /idp, which is added onto the URL endpoint by CAS automatically. The API is expected to produce a successful 200 - OK response status on all operations outlined below:

    Method Description
    GET The response is expected to produce a JSON document outlining keys and metadata as indicated above. An appliesTo parameter may be passed to indicate the document owner and applicability, where a value of CAS indicates the CAS server as the global owner of the metadata and keys.
    POST Store the metadata and keys to finalize the metadata generation process. The request body contains the JSON document that outlines metadata and keys as indicated above.

    Per Service

    Identity provider metadata, certificates and keys can also be defined on a per-service basis to override the global defaults. Metadata documents that would be applicable to a service definition need to adjust the appliesTo field in the metadata document to carry the service definition’s name and numeric identifier using the [service-name]-[service-numeric-identifier] format.