Google Authenticator Authentication

Google Authenticator generates 2-step verification codes on your phone. With 2-step verification signing in will require a code generated by the Google Authenticator app in addition to primary authentication. Learn more about the topic here.

Note that the functionality presented here should also be compatible with the likes of LastPass Authenticator, etc.

Configuration

Support is enabled by including the following module in the overlay:

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

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

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

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

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.

Repository Cleaner

A background cleaner process is also automatically scheduled to scan the repository periodically and remove expired device registration records based on configured parameters. In the default setting, devices expire after a fixed period since a user registered their device.

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

Configuration Metadata

Be Selective

YAGNI

Naming Convention

Validation

Indexed Settings

Actuator Endpoints

The following endpoints are provided by CAS:

Token Repository

In order to prevent reuse of tokens issued, CAS will attempt to keep track of tokens that are successfully used to authenticate the user. The repository that holds registration records and tokens is periodically scanned and cleaned up so that expired and previously used tokens may be removed.

Registration

By default, an account registry implementation is included that collects user device registrations and saves them into memory. Issued tokens are also captured into a self-cleaning cache to prevent token reuse for a configurable period of time. This option should only be used for demo and testing purposes. Production deployments of this feature will require a separate implementation of the registry that is capable to register accounts into persistent storage.

Note that each individual account is allowed to register multiple devices to be used later for multifactor authentication. Duration the authentication flow, the user will be asked to select the appropriate device for authentication if multiple device registration records are found. The ability to handle multiple device registration records can be controlled via CAS settings.

Storage	Description
JPA	See this guide.
CouchDb	See this guide.
MongoDb	See this guide.
DynamoDb	See this guide.
Redis	See this guide.
LDAP	See this guide.
REST	See this guide.
JSON	See this guide.

REST Protocol Credential Extraction

In the event that the CAS REST Protocol is turned on, a special credential extractor is injected into the REST authentication engine in order to recognize credentials and authenticate them as part of the REST request. The expected parameter name in the request body is gauthotp. The account identifier may also be passed using the gauthacct parameter in the request body.

Account Profile Management

The integration with Google Authenticator is able to provide user device registration information to the account profile management feature in CAS. See this guide for better details.