APEREO CASDocumentation

Enterprise Authentication for All Earthlings and Beyond

Identity, Single Sign-On and Access Management
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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:

cas.authn.accept.password-encoder.encoding-algorithmThe encoding algorithm to use such as MD5 .
no default
Required

The encoding algorithm to use such as MD5. Relevant when the type used is DEFAULT or GLIBC_CRYPT. When used with PasswordEncoderTypes#PBKDF2, it should be one of PBKDF2WithHmacSHA1, PBKDF2WithHmacSHA256 or PBKDF2WithHmacSHA512.

Type
String
Default
none
Defined by
PasswordEncoderProperties
cas.authn.accept.password-encoder.typeDefine the password encoder type to use.
NONE
Required

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} or {SSHA} 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.
Type
String
Default
NONE
Defined by
PasswordEncoderProperties
cas.authn.accept.password-policy.groovy.locationThe location of the resource.
no default
Required

The location of the resource. Resources can be URLs, or files found either on the classpath or outside somewhere in the file system.

In the event the configured resource is a Groovy script, especially if the script is set to reload on changes, you may need to adjust the total number of inotify instances. On Linux, you may need to add the following line to /etc/sysctl.conf: fs.inotify.max_user_instances = 256.

You can check the current value via cat /proc/sys/fs/inotify/max_user_instances.

In situations and scenarios where CAS is able to automatically watch the underlying resource for changes and detect updates and modifications dynamically, you may be able to specify the following setting as either an environment variable or system property with a value of false to disable the resource watcher: org.apereo.cas.util.io.PathWatcherService.

Type
Resource
Default
none
Defined by
GroovyPasswordPolicyProperties
cas.authn.accept.principal-transformation.groovy.locationThe location of the resource.
no default
Required

The location of the resource. Resources can be URLs, or files found either on the classpath or outside somewhere in the file system.

In the event the configured resource is a Groovy script, especially if the script is set to reload on changes, you may need to adjust the total number of inotify instances. On Linux, you may need to add the following line to /etc/sysctl.conf: fs.inotify.max_user_instances = 256.

You can check the current value via cat /proc/sys/fs/inotify/max_user_instances.

In situations and scenarios where CAS is able to automatically watch the underlying resource for changes and detect updates and modifications dynamically, you may be able to specify the following setting as either an environment variable or system property with a value of false to disable the resource watcher: org.apereo.cas.util.io.PathWatcherService.

Type
Resource
Default
none
Defined by
GroovyPrincipalTransformationProperties
cas.authn.accept.usersAccepted users for authentication, in the syntax of uid::password .
no default
Required

Accepted users for authentication, in the syntax of uid::password.

Type
String
Default
none
Defined by
AcceptAuthenticationProperties
cas.authn.accept.credential-criteriaA 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.
no default
Regex
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.
Type
String
Default
none
Defined by
AcceptAuthenticationProperties
cas.authn.accept.enabledIndicates whether the authentication strategy is enabled.
true

Indicates whether the authentication strategy is enabled. The strategy may also be disabled explicitly if the #users is left blank.

Type
Boolean
Default
true
Defined by
AcceptAuthenticationProperties
cas.authn.accept.nameName of the authentication handler.
no default

Name of the authentication handler.

Type
String
Default
none
Defined by
AcceptAuthenticationProperties
cas.authn.accept.orderOrder of the authentication handler in the chain.
no default

Order of the authentication handler in the chain.

Type
Integer
Default
none
Defined by
AcceptAuthenticationProperties
cas.authn.accept.password-encoder.character-encodingThe encoding algorithm to use such as 'UTF-8'.
UTF-8

The encoding algorithm to use such as 'UTF-8'. Relevant when the type used is DEFAULT.

Type
String
Default
UTF-8
Defined by
PasswordEncoderProperties
cas.authn.accept.password-encoder.hash-lengthWhen used by PasswordEncoderTypes#ARGON2 , it indicates the hash strength/length.
16

When used by PasswordEncoderTypes#ARGON2, it indicates the hash strength/length.

Type
Integer
Default
16
Defined by
PasswordEncoderProperties
cas.authn.accept.password-encoder.iterationsWhen used by PasswordEncoderTypes#PBKDF2 , it indicates the required number of iterations.
310000

When used by PasswordEncoderTypes#PBKDF2, it indicates the required number of iterations.

Type
Integer
Default
310000
Defined by
PasswordEncoderProperties
cas.authn.accept.password-encoder.secretSecret to use with PasswordEncoderTypes#STANDARD , PasswordEncoderTypes#PBKDF2 , PasswordEncoderTypes#BCRYPT , PasswordEncoderTypes#GLIBC_CRYPT password encoders.
no default

Secret to use with PasswordEncoderTypes#STANDARD, PasswordEncoderTypes#PBKDF2, PasswordEncoderTypes#BCRYPT, PasswordEncoderTypes#GLIBC_CRYPT password encoders. Secret usually is an optional setting.

Type
String
Default
none
Defined by
PasswordEncoderProperties
cas.authn.accept.password-encoder.strengthStrength or number of iterations to use for password hashing.
16

Strength or number of iterations to use for password hashing. Usually relevant when dealing with PasswordEncoderTypes#BCRYPT, PasswordEncoderTypes#PBKDF2 or PasswordEncoderTypes#GLIBC_CRYPT. When used by PasswordEncoderTypes#ARGON2 or PasswordEncoderTypes#PBKDF2, it indicates the salt strength.

Type
Integer
Default
16
Defined by
PasswordEncoderProperties
cas.authn.accept.password-policy.account-state-handling-enabledIndicates whether account state handling should be enabled to process warnings or errors reported back from the authentication response, produced by the source.
true

Indicates whether account state handling should be enabled to process warnings or errors reported back from the authentication response, produced by the source.

Type
Boolean
Default
true
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.display-warning-on-matchIndicates if warning should be displayed, when the ldap attribute value matches the #warningAttributeValue .
true

Indicates if warning should be displayed, when the ldap attribute value matches the #warningAttributeValue.

Type
Boolean
Default
true
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.enabledWhether password policy should be enabled.
true

Whether password policy should be enabled.

Type
Boolean
Default
true
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.login-failuresWhen dealing with FreeIPA, indicates the number of allows login failures.
5

When dealing with FreeIPA, indicates the number of allows login failures.

Type
Integer
Default
5
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.policy-attributesKey-value structure (Map) that indicates a list of boolean attributes as keys.
no default

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

Type
Map<String,Class<? extends LoginException>>
Default
none
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.strategyDecide how authentication should handle password policy changes.
DEFAULT
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.
Type
PasswordPolicyProperties.PasswordPolicyHandlingOptions
Default
DEFAULT
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.warn-allAlways display the password expiration warning regardless.
false

Always display the password expiration warning regardless.

Type
Boolean
Default
false
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.warning-attribute-nameUsed by an account state handling policy that only calculates account warnings in case the entry carries this attribute.
no default

Used by an account state handling policy that only calculates account warnings in case the entry carries this attribute.

Type
String
Default
none
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.warning-attribute-valueUsed by an account state handling policy that only calculates account warnings in case the entry carries an attribute #warningAttributeName whose value matches this field.
no default

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.

Type
String
Default
none
Defined by
PasswordPolicyProperties
cas.authn.accept.password-policy.warning-daysThis is used to calculate a warning period to see if account expiry is within the calculated window.
30

This is used to calculate a warning period to see if account expiry is within the calculated window.

Type
Integer
Default
30
Defined by
PasswordPolicyProperties
cas.authn.accept.principal-transformation.blocking-patternA regular expression that will be used against the username to match for blocking/forbidden values.
no default
SpEL

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.

Type
String
Default
none
Defined by
PrincipalTransformationProperties
Supports
Spring Expression Language
cas.authn.accept.principal-transformation.case-conversionIndicate whether the principal identifier should be transformed into upper-case, lower-case, etc.
NONE
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.
Type
PrincipalTransformationProperties.CaseConversion
Default
NONE
Defined by
PrincipalTransformationProperties
cas.authn.accept.principal-transformation.patternA regular expression that will be used against the provided username for username extractions.
no default
SpEL

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.

Type
String
Default
none
Defined by
PrincipalTransformationProperties
Supports
Spring Expression Language
cas.authn.accept.principal-transformation.prefixPrefix to add to the principal id prior to authentication.
no default
SpEL

Prefix to add to the principal id prior to authentication.

Type
String
Default
none
Defined by
PrincipalTransformationProperties
Supports
Spring Expression Language
cas.authn.accept.principal-transformation.suffixSuffix to add to the principal id prior to authentication.
no default
SpEL

Suffix to add to the principal id prior to authentication.

Type
String
Default
none
Defined by
PrincipalTransformationProperties
Supports
Spring Expression Language
cas.authn.accept.stateDefine the scope and state of this authentication handler and the lifecycle in which it can be invoked or activated.
active
Define the scope and state of this authentication handler and the lifecycle in which it can be invoked or activated. Available values are as follows:
  • ACTIVE: Active authentication handler, and is invoked by default automatically to verify credentials globally.
  • STANDBY: Authentication handler is in a semi-enabled state, waiting to be called only on-demand when explicitly asked for.
Type
AuthenticationHandlerStates
Default
active
Defined by
AcceptAuthenticationProperties

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.

Groovy scripting

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.

Authentication

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.

Password encoding

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

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.

Principal transformation

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.

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:

authenticationHandlers
CAS endpoint2 operationsNot exposed by defaultcas-server-support-reports
1

Include the module that provides this endpoint in the WAR overlay:

Show in CAS Initializr Generate CAS Server WAR Overlay 


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





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implementation "org.apereo.cas:cas-server-support-reports:${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-reports"
}





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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-reports"
}
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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.authenticationHandlers.access=UNRESTRICTED
management.endpoints.web.exposure.include=authenticationHandlers

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

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.