APEREO CASDocumentation

Enterprise Authentication for All Earthlings and Beyond

Identity, Single Sign-On and Access Management
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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 are included automatically and are listed 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:

cas.authn.saml-idp.metadata.rest.crypto.encryption.keyThe encryption key is a string whose length is defined by the encryption key size setting.
no default
RequiredSpEL

The encryption key is a string whose length is defined by the encryption key size setting.

Type
String
Default
none
Defined by
EncryptionJwtCryptoProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.rest.crypto.signing.keyThe signing key is a string whose length is defined by the signing key size setting.
no default
RequiredSpEL

The signing key is a string whose length is defined by the signing key size setting.

Type
String
Default
none
Defined by
SigningJwtCryptoProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.rest.urlThe endpoint URL to contact and retrieve attributes.
no default
RequiredSpEL

The endpoint URL to contact and retrieve attributes.

Type
String
Default
none
Defined by
RestSamlMetadataProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.rest.basic-auth-passwordIf REST endpoint is protected via basic authentication, specify the password for authentication.
no default

If REST endpoint is protected via basic authentication, specify the password for authentication.

Type
String
Default
none
Defined by
RestSamlMetadataProperties
cas.authn.saml-idp.metadata.rest.basic-auth-usernameIf REST endpoint is protected via basic authentication, specify the username for authentication.
no default

If REST endpoint is protected via basic authentication, specify the username for authentication.

Type
String
Default
none
Defined by
RestSamlMetadataProperties
cas.authn.saml-idp.metadata.rest.crypto.algThe signing/encryption algorithm to use.
no default

The signing/encryption algorithm to use.

Type
String
Default
none
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.authn.saml-idp.metadata.rest.crypto.enabledWhether crypto operations are enabled.
true

Whether crypto operations are enabled.

Type
Boolean
Default
true
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.authn.saml-idp.metadata.rest.crypto.encryption.key-sizeThe encryption key size.
512

The encryption key size.

Type
Integer
Default
512
Defined by
EncryptionJwtCryptoProperties
cas.authn.saml-idp.metadata.rest.crypto.signing.key-sizeThe signing key size.
512

The signing key size.

Type
Integer
Default
512
Defined by
SigningJwtCryptoProperties
cas.authn.saml-idp.metadata.rest.crypto.strategy-typeControl the cipher sequence of operations.
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.
Type
String
Default
ENCRYPT_AND_SIGN
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.authn.saml-idp.metadata.rest.headersHeaders, defined as a Map, to include in the request when making the REST call.
no default

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.

Type
Map<String,String>
Default
none
Defined by
RestSamlMetadataProperties
cas.authn.saml-idp.metadata.rest.idp-metadata-enabledWhether identity provider metadata artifacts are expected to be found in the database.
false

Whether identity provider metadata artifacts are expected to be found in the database.

Type
Boolean
Default
false
Defined by
RestSamlMetadataProperties
cas.authn.saml-idp.metadata.rest.maximum-retry-attemptsWhen attempting to reach the endpoint, this setting controls the number of retry attempts that CAS should execute Setting this value to a zero or negative value will disable the retry policy.
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When attempting to reach the endpoint, this setting controls the number of retry attempts that CAS should execute Setting this value to a zero or negative value will disable the retry policy.

Type
Integer
Default
3
Defined by
RestSamlMetadataProperties
cas.authn.saml-idp.metadata.rest.methodHTTP method to use when contacting the rest endpoint.
GET

HTTP method to use when contacting the rest endpoint. Examples include GET, POST, etc.

Type
String
Default
GET
Defined by
RestSamlMetadataProperties

Required settings may be needed to activate or affect the feature; review them even when they have a default. Optional settings only need to be set to change a default or to turn on the behavior they control. Third party settings belong to libraries such as Spring Boot that CAS builds on; their own documentation may have more detail.

Signing & encryption

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.

Notes on configuration

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, especially 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.

Actuator Endpoints

The following endpoints are provided by CAS:

samlIdPRegisteredServiceMetadata
CAS endpoint4 operationsNot exposed by default
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Turn the endpoint on and expose it over the web. One entry covers every operation. By default only info, health and status are exposed.



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management.endpoint.samlIdPRegisteredServiceMetadata.access=UNRESTRICTED
management.endpoints.web.exposure.include=samlIdPRegisteredServiceMetadata

Endpoints may be mapped to other paths. For example, to serve health at healthcheck:



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management.endpoints.web.path-mapping.health=healthcheck

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.