Configuration

The CAS authentication process is primarily controlled by an authentication manager, which orchestrates a collection of authentication handlers.

Authentication Manager

CAS ships with a single yet flexible authentication manager which performs authentication according to the following contract.

For any given credential the manager does the following:

  1. Iterate over all configured authentication handlers.
  2. Attempt to authenticate a credential if a handler supports it.
  3. On success attempt to resolve a principal.
  4. Check whether a resolver is configured for the handler that authenticated the credential.
  5. If a suitable resolver is found, attempt to resolve the principal.
  6. If a suitable resolver is not found, use the principal resolved by the authentication handler.
  7. Check whether the security policy (e.g. any, all) is satisfied.
  8. If security policy is met return immediately.
  9. Continue if security policy is not met.
  10. After all credentials have been attempted check security policy again and throw AuthenticationException if not satisfied.

There is an implicit security policy that requires at least one handler to successfully authenticate a credential.

Authentication Handlers

There are a variety of authentication handlers and methods supported by CAS. Use the menu to navigate around the site and choose. By default, CAS is configured to accept a pre-defined set of credentials that are supplied via the CAS configuration.

:warning: Default Credentials

To test the default authentication scheme in CAS, use casuser and Mellon as the username and password respectively. These are automatically configured via the static authentication handler, and MUST be removed from the configuration prior to production rollouts.

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.

CAS takes advantage of Apache Groovy in forms of either embedded or external scripts that allow one to, by default, dynamically build constructs, attributes, access strategies and a lot more. To activate the functionality described here, you may need to prepare CAS to support and integrate with Apache Groovy.

Please review this guide to configure your build.

If you need to design your own password encoding scheme where the type is specified as a fully qualified Java class name, the structure of the class would be similar to the following:



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package org.example.cas;

import org.springframework.security.crypto.codec.*;
import org.springframework.security.crypto.password.*;

public class MyEncoder extends AbstractPasswordEncoder {
    @Override
    protected byte[] encode(CharSequence rawPassword, byte[] salt) {
        return ...
    }
}

If you need to design your own password encoding scheme where the type is specified as a path to a Groovy script, the structure of the script would be similar to the following:



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import java.util.*

byte[] run(final Object... args) {
    def (rawPassword,generatedSalt,logger,applicationContext) = args
    logger.debug("Encoding password...")
    return ...
}

Boolean matches(final Object... args) {
    def (rawPassword,encodedPassword,logger,applicationContext) = args
    logger.debug("Does match or not ?");
    return ...

To prepare CAS to support and integrate with Apache Groovy, please review this guide.

Password Policy Strategies

If the password policy strategy is to be handed off to a Groovy script, the outline of the script may be as follows:



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import java.util.*
import org.ldaptive.auth.*
import org.apereo.cas.*
import org.apereo.cas.authentication.*
import org.apereo.cas.authentication.support.*

List<MessageDescriptor> run(final Object... args) {
    def (response,configuration,logger,applicationContext) = args
    logger.info("Handling password policy [{}] via ${configuration.getAccountStateHandler()}", response)

    def accountStateHandler = configuration.getAccountStateHandler()
    return accountStateHandler.handle(response, configuration)
}

The parameters passed are as follows:

Parameter Description
response The LDAP authentication response of type org.ldaptive.auth.AuthenticationResponse
configuration The LDAP password policy configuration carrying the account state handler defined.
logger The object responsible for issuing log messages such as logger.info(...).
applicationContext The Spring ApplicationContext that allows one to interact with the runtime.

To prepare CAS to support and integrate with Apache Groovy, please review this guide.

Authentication handlers that generally deal with username-password credentials can be configured to transform the user id prior to executing the authentication sequence. Each authentication strategy in CAS provides settings to properly transform the principal. Refer to the relevant settings for the authentication strategy at hand to learn more.

Authentication handlers as part of principal transformation may also be provided a path to a Groovy script to transform the provided username. The outline of the script may take on the following form:



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String run(final Object... args) {
    def (providedUsername,logger) = args
    return providedUsername.concat("SomethingElse")
}

To prepare CAS to support and integrate with Apache Groovy, please review this guide.

Certain authentication handlers are allowed to determine whether they can operate on the provided credential and as such lend themselves to be tried and tested during the authentication handler selection phase. The credential criteria may be one of the following options:

  • A regular expression pattern that is tested against the credential identifier.
  • A fully qualified class name of your own design that looks similar to the below example:


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import java.util.function.Predicate;
import org.apereo.cas.authentication.Credential;

public class PredicateExample implements Predicate<Credential> {
    @Override
    public boolean test(final Credential credential) {
        // Examine the credential and return true/false
    }
}
  • Path to an external Groovy script that looks similar to the below example:


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import org.apereo.cas.authentication.Credential
import java.util.function.Predicate

class PredicateExample implements Predicate<Credential> {
    @Override
    boolean test(final Credential credential) {
        // test and return result
    }
}

To prepare CAS to support and integrate with Apache Groovy, please review this guide.

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.

Actuator Endpoints

The following endpoints are provided by CAS:

 Get available authentication handler by name.

 Get collection of available authentication handlers.


Resolution Strategy

Please see this guide for more info.

Authentication Sequence

At runtime, CAS maintains a collection of authentication handlers/strategies that typically execute one after another. Each CAS module that presents a form of authentication strategy will insert itself into this collection at bootstrap time. At the end of this process, the result of all authentication transactions is collected and optionally processed by an authentication policy where success/failure of certain strategies/sources may be taken into account to fully satisfy the authentication requirements. The collection of authentication handlers tries to preserve order in a rather more deterministic way. The idea is that adopters can assign an order value to an authentication handler thereby explicitly positioning it in the collection and controlling its execution sequence.

Authentication Pre/Post Processing

Please see this guide for more details.

Naming Strategy

Each authentication handler in CAS can be named via CAS settings and if left undefined, the short name of the handler component itself is used (i.e. LdapAuthenticationHandler). The name itself can be any arbitrary string and typically is used to identify and refer to the handler components in areas such as required authentication for a service, etc. In the event that multiple authentication handlers of the same type are defined, it is RECOMMENDED that each be given a unique name so as to avoid conflicts. Authentication failures are typically collected in CAS by the name of each authentication handler. Leaving the name undefined will likely result in subsequent components in the authentication chain overriding previous results.

Authentication Policy

Please see authentication security policies for more details.

Long Term Authentication

CAS has support for long term Ticket Granting Tickets, a feature that is also referred to as “Remember Me” to extend the length of the SSO session beyond the typical configuration. Please see this guide for more details.

Proxy Authentication

Please see this guide for more details.

Multifactor Authentication (MFA)

Please see this guide for more details.

Login Throttling

CAS provides a facility for limiting failed login attempts to support password guessing and related abuse scenarios. Please see this guide for additional details on login throttling.

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. Please see this guide for additional details.