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.

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.

  • cas.authn.accept.password-encoder.encoding-algorithm=
  • The encoding algorithm to use such as 'MD5'. Relevant when the type used is 'DEFAULT' or 'GLIBC_CRYPT'.

  • cas.authn.accept.password-encoder.type=NONE
  • Define the password encoder type to use. Type may be specified as blank or 'NONE' to disable password encoding. It may also refer to a fully-qualified class name that implements the Spring Security's PasswordEncoder interface if you wish you define your own encoder. The following types may be used:

    • NONE: No password encoding (i.e. plain-text) takes place.
    • DEFAULT: Use the DefaultPasswordEncoder of CAS. For message-digest algorithms via character-encoding and encoding-algorithm.
    • BCRYPT: Use the BCryptPasswordEncoder based on the strength provided and an optional secret.
    • SCRYPT: Use the SCryptPasswordEncoder.
    • PBKDF2: Use the Pbkdf2PasswordEncoder based on the strength provided and an optional secret.
    • STANDARD: Use the StandardPasswordEncoder based on the secret provided.
    • SSHA: Use the LdapShaPasswordEncoder supports Ldap SHA and SSHA (salted-SHA). The values are base-64 encoded and have the label SHA</code> or SSHA</code> prepended to the encoded hash.
    • GLIBC_CRYPT: Use the GlibcCryptPasswordEncoder based on the encoding-algorithm, strength provided and an optional secret.
    • org.example.MyEncoder: An implementation of PasswordEncoder of your own choosing.
    • file:///path/to/script.groovy: Path to a Groovy script charged with handling password encoding operations.

  • cas.authn.accept.password-policy.groovy.location=
  • The location of the resource. Resources can be URLS, or files found either on the classpath or outside somewhere in the file system.

  • cas.authn.accept.principal-transformation.groovy.location=
  • The location of the resource. Resources can be URLS, or files found either on the classpath or outside somewhere in the file system.

    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.

  • cas.authn.accept.credential-criteria=
  • A number of 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:

    • 1) A regular expression pattern that is tested against the credential identifier.
    • 2) A fully qualified class name of your own design that implements Predicate.
    • 3) Path to an external Groovy script that implements the same interface.

  • cas.authn.accept.enabled=true
  • Indicates whether the authentication strategy is enabled. The strategy may also be disabled explicitly if the #users is left blank.

  • cas.authn.accept.name=
  • Name of the authentication handler.

  • cas.authn.accept.order=
  • Order of the authentication handler in the chain.

  • cas.authn.accept.password-encoder.character-encoding=UTF-8
  • The encoding algorithm to use such as 'UTF-8'. Relevant when the type used is 'DEFAULT'.

  • cas.authn.accept.password-encoder.secret=
  • Secret to use with STANDARD, PBKDF2, BCRYPT, GLIBC_CRYPT password encoders. Secret usually is an optional setting.

  • cas.authn.accept.password-encoder.strength=16
  • Strength or number of iterations to use for password hashing. Usually relevant when dealing with PBKDF2 or BCRYPT encoders. Used by GLIBC_CRYPT encoders as well.

  • cas.authn.accept.password-policy.account-state-handling-enabled=true
  • Indicates whether account state handling should be enabled to process warnings or errors reported back from the authentication response, produced by the source.

  • cas.authn.accept.password-policy.display-warning-on-match=true
  • Indicates if warning should be displayed, when the ldap attribute value matches the #warningAttributeValue.

  • cas.authn.accept.password-policy.enabled=true
  • Whether password policy should be enabled.

  • cas.authn.accept.password-policy.login-failures=5
  • When dealing with FreeIPA, indicates the number of allows login failures.

  • cas.authn.accept.password-policy.policy-attributes=
  • Key-value structure (Map) that indicates a list of boolean attributes as keys. If either attribute value is true, indicating an account state is flagged, the corresponding error can be thrown. Example accountLocked=javax.security.auth.login.AccountLockedException

  • cas.authn.accept.password-policy.strategy=
  • Decide how authentication should handle password policy changes. Available values are as follows:

    • DEFAULT: Default option to handle policy changes.
    • GROOVY: Handle account password policies via Groovy.
    • REJECT_RESULT_CODE: Strategy to only activate password policy if the authentication response code is not blocked.

  • cas.authn.accept.password-policy.warn-all=false
  • Always display the password expiration warning regardless.

  • cas.authn.accept.password-policy.warning-attribute-name=
  • Used by an account state handling policy that only calculates account warnings in case the entry carries this attribute.

  • cas.authn.accept.password-policy.warning-attribute-value=
  • Used by an account state handling policy that only calculates account warnings in case the entry carries an attribute #warningAttributeName whose value matches this field.

  • cas.authn.accept.password-policy.warning-days=30
  • This is used to calculate a warning period to see if account expiry is within the calculated window.

  • cas.authn.accept.principal-transformation.blocking-pattern=
  • A regular expression that will be used against the username to match for blocking/forbidden values. If a match is found, an exception will be thrown and principal transformation will fail.

  • cas.authn.accept.principal-transformation.case-conversion=
  • Indicate whether the principal identifier should be transformed into upper-case, lower-case, etc. Available values are as follows:

    • NONE: No conversion.
    • LOWERCASE: Lowercase conversion.
    • UPPERCASE: Uppercase conversion.

  • cas.authn.accept.principal-transformation.pattern=
  • A regular expression that will be used against the provided username for username extractions. On a successful match, the first matched group in the pattern will be used as the extracted username.

  • cas.authn.accept.principal-transformation.prefix=
  • Prefix to add to the principal id prior to authentication.

  • cas.authn.accept.principal-transformation.suffix=
  • Suffix to add to the principal id prior to authentication.

  • cas.authn.accept.users=
  • Accepted users for authentication, in the syntax of uid::password.

    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 = args[0]
        def generatedSalt = args[1]
        def logger = args[2]
        def casApplicationContext = args[3]
    
        logger.debug("Encoding password...")
        return ...
    }
    
    Boolean matches(final Object... args) {
        def rawPassword = args[0]
        def encodedPassword = args[1]
        def logger = args[2]
        def casApplicationContext = args[3]
    
       logger.debug("Does match or not ?");
       return ...
    

    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 = args[0]
        def configuration = args[1];
        def logger = args[2]
        def applicationContext = args[3]
    
        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(...).

    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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    def String run(final Object... args) {
        def providedUsername = args[0]
        def logger = args[1]
        return providedUsername.concat("SomethingElse")
    }
    

    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
        }
    }
    

    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 below 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.S ettings 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.

    Administrative Endpoints

    The following endpoints are provided by CAS:

    Endpoint Description
    authenticationHandlers A GET request presents the collection of registered authentication handlers. An individual authentication handler can be queried via GET by its name using a selector path (i.e. authenticationHandlers/{name}).

    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.

    Principal Resolution

    Please see this guide 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.