JWKS Storage - OpenID Connect Authentication

The following strategies can be used to generate, manage and storage a JSON Web keystore.

Default

By default, a global keystore can be expected and defined via CAS properties as a path on the file system. The format of the keystore file is similar to the following:

{
  "keys": [
    {
      "d": "...",
      "e": "AQAB",
      "use": "sig",
      "n": "...",
      "kty": "RSA",
      "kid": "cas",
      "state": 0
    }
  ]
}

Clustered Deployments

When deploying CAS in a cluster, you must make sure all CAS server nodes have access to and share an identical and exact copy of the keystore file. Keystore differences will lead to various validation failures and application integration issues.

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.

The keystore is automatically watched and monitored by CAS for changes. As changes are detected, CAS will invalidate the cache and will reload the keystore once again.

JPA

Keystore generation can be outsourced to an external relational database, such as MySQL, etc.

Support is enabled by including the following module in the WAR Overlay:

<dependency>
  <groupId>org.apereo.cas</groupId>
  <artifactId>cas-server-support-jpa-hibernate</artifactId>
  <version>${cas.version}</version>
</dependency>

implementation "org.apereo.cas:cas-server-support-jpa-hibernate:${project.'cas.version'}"

dependencyManagement {
  imports {
    mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
  }
}

dependencies {  
  implementation "org.apereo.cas:cas-server-support-jpa-hibernate"
}

To learn how to configure database drivers and JPA implementation options, please review this guide.

The following settings and properties are available from the CAS configuration catalog:

Configuration Metadata

Be Selective

YAGNI

Naming Convention

Validation

Indexed Settings

MongoDb

Keystore generation can be outsourced to an external MongoDb instance.

Support is enabled by including the following module in the WAR Overlay:

<dependency>
  <groupId>org.apereo.cas</groupId>
  <artifactId>cas-server-support-mongo-core</artifactId>
  <version>${cas.version}</version>
</dependency>

implementation "org.apereo.cas:cas-server-support-mongo-core:${project.'cas.version'}"

dependencyManagement {
  imports {
    mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
  }
}

dependencies {  
  implementation "org.apereo.cas:cas-server-support-mongo-core"
}

The following settings and properties are available from the CAS configuration catalog:

Configuration Metadata

Be Selective

YAGNI

Naming Convention

Validation

Indexed Settings

REST

Keystore generation can be outsourced to an external REST API. Endpoints must be designed to accept/process application/json and generally should return a 2xx response status code.

The following requests are made by CAS to the endpoint:

Operation	Parameters	Description	Result
`GET`	N/A	Retrieve the keystore, or generate one.	`2xx` status code; JWKS resource in response body.
`POST`	JWKS in request body.	Store the keystore.	`2xx` status code.

The following settings and properties are available from the CAS configuration catalog:

Configuration Metadata

Be Selective

YAGNI

Naming Convention

Validation

Indexed Settings

Groovy

Keystore generation can be outsourced to an external Groovy script whose body should be defined as such:

import org.apereo.cas.oidc.jwks.*
import org.jose4j.jwk.*

def run(Object[] args) {
    def logger = args[0]
    logger.info("Generating JWKS for CAS...")
    def jsonWebKeySet = "{ \"keys\": [...] }"
    return jsonWebKeySet
}

def store(Object[] args) {
    def jwks = args[0] as JsonWebKeySet
    def logger = args[1]
    logger.info("Storing JWKS for CAS...")
    return jwks
}

def find(Object[] args) {
    def logger = args[0]
    logger.info("Looking up JWKS...")
    return new JsonWebKeySet(...)
}

The following settings and properties are available from the CAS configuration catalog:

Configuration Metadata

Be Selective

YAGNI

Naming Convention

Validation

Indexed Settings

Custom

It is possible to design and inject your own keystore generation strategy into CAS using the following @Bean that would be registered in a @Configuration class:

@Bean(initMethod = "generate")
public OidcJsonWebKeystoreGeneratorService oidcJsonWebKeystoreGeneratorService() {
    return new MyJsonWebKeystoreGeneratorService(...);
}

Your configuration class needs to be registered with CAS. See this guide for better details.