SSO Cookie

A ticket-granting cookie is an HTTP cookie set by CAS upon the establishment of a single sign-on session. This cookie maintains login state for the client, and while it is valid, the client can present it to CAS in lieu of primary credentials.

The cookie value is linked to the active ticket-granting ticket, the remote IP address that initiated the request as well as the user agent that submitted the request. The final cookie value is then encrypted and signed.

These keys MUST be regenerated per your specific environment. Each key is a JSON Web Token with a defined length per the algorithm used for encryption and signing.

In the event that keys are not generated by the deployer, CAS will attempt to auto-generate keys and will output the result for each respected key. The deployer MUST attempt to copy the generated keys over to the appropriate settings in their CAS properties file, specially when running a multi-node CAS deployment. Failure to do so will prevent CAS to appropriate decrypt and encrypt the cookie value and will prevent successful single sign-on.

:information_source: Forced Authentication

Each application can opt out of a single sign-on session on a per-request basis. The availability of this behavior does depend on the authentication protocol used by the application. For example, applications that use the CAS protocol can opt out of single sign-on through the renew parameter or the CAS server may conditionally opt the service out based on the policies defined for the application in the service registry

Configuration

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. 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.

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.

The cookie has the following properties:

  1. It is marked as secure.
  2. Depending on container support, the cookie would be marked as http-only automatically.
  3. The cookie value is encrypted and signed via secret keys that need to be generated upon deployment.

If keys are left undefined, on startup CAS will notice that no keys are defined and it will appropriately generate keys for you automatically. Your CAS logs will then show the following snippet:



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WARN [...] - <Secret key for encryption is not defined. CAS will auto-generate the encryption key>
WARN [...] - <Generated encryption key ABC of size ... . The generated key MUST be added to CAS settings.>
WARN [...] - <Secret key for signing is not defined. CAS will auto-generate the signing key>
WARN [...] - <Generated signing key XYZ of size ... . The generated key MUST be added to CAS settings.>

You should then grab each generated key for encryption and signing, and put them inside your CAS properties for each setting. If you wish you manually generate keys, you may use the following tool.

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

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.

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.

SSO Expiration Policy

The single sign-on expiration policy that is tied to the CAS single sign-on cookie is mainly controlled by a specific ticket type that represents the single sign-on session managed by the CAS server.

See this page for more.

SameSite Attribute

CAS configuration allows the deployer to control and modify the SameAttribute cookie attribute statically. The deployer also has the option to generate this cookie attribute dynamically via the following strategies.

  • The cookie setting in CAS configuration may point to a Groovy script that is tasked to generate the SameAttribute cookie attribute. The outline of the script may be as follows:

    

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    import org.apereo.cas.web.cookie.*

def run(final Object... args) {
    def (request,response,context,logger) = args
    
    logger.info("Generating SameSite for ${context.name}")
    return "SameSite=Lax;"
}

    The parameters that may be passed are as follows:

    Parameter Description
    request The HTTP request object.
    response The HTTP response object.
    context The cookie configuration context that points to the cookie configuration and other helper objects.
    logger The object responsible for issuing log messages such as logger.info(...).

  • The cookie setting in CAS configuration may point to a Java class using its FQDN that is tasked to generate the SameAttribute cookie attribute.

    

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    public class MyCookieSameSitePolicy implements CookieSameSitePolicy {
    @Override
    public Optional<String> build(HttpServletRequest request, 
                                  HttpServletResponse response, 
                                  CookieGenerationContext context) {
        return Optional.of("SameSite=Lax;");
    }
}

By default, forced authentication requests that challenge the user for credentials either via the renew request parameter (that is, using the CAS protocol), or via the service-specific setting of the CAS service registry will always generate the ticket-granting cookie nonetheless. What this means is, logging in to a non-SSO-participating application via CAS nonetheless creates a valid CAS single sign-on session that will be honored on a subsequent attempt to authenticate to a SSO-participating application.

The cookie generation strategy can also be customized on a per-application basis. For additional details, please review this guide.