Google reCAPTCHA

reCAPTCHA is a Google service that protects your CAS deployment from spam and abuse. It uses advanced risk analysis techniques to tell humans and bots apart. CAS supports the reCAPTCHA API v2 and v3.

Support is enabled by including the following module in the WAR Overlay:

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

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

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

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

dependencies {
    /*
        The following platform references should be included automatically and are listed here 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-captcha"
}

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.google-recaptcha.enabled=true

Whether reCAPTCHA should be enabled.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

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.

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.enabled=true

This is the most common form of property configuration that is recognized by CAS, regardless of the actual property source, which might in fact be managed separately outside the CAS environment, by another system or cloud framework.

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    enabled: "true"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.enabled="true" -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory. Note the placement of the system property which must be specified before the CAS web application is launched.

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_ENABLED="true"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.enabled="true"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.score=0.5

Google reCAPTCHA v3 returns a score (1.0 is very likely a good interaction, 0.0 is very likely a bot). reCAPTCHA learns by seeing real traffic on your site. For this reason, scores in a staging environment or soon after implementing may differ from production. As reCAPTCHA v3 doesn't ever interrupt the user flow, you can first run reCAPTCHA without taking action and then decide on thresholds by looking at your traffic in the admin console. By default, you can use a threshold of 0.5.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.score=0.5

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    score: "0.5"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.score="0.5" -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_SCORE="0.5"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.score="0.5"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.secret=

The reCAPTCHA site secret.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.secret=...

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    secret: "..."

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.secret="..." -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_SECRET="..."

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.secret="..."

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.site-key=

The reCAPTCHA site key.

This setting supports the Spring Expression Language.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.site-key=...

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    site-key: "..."

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.site-key="..." -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_SITE_KEY="..."

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.site-key="..."

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

_{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.google-recaptcha.activate-for-ip-address-pattern=

A regular expression pattern to indicate that captcha should be activated when the remote IP address matches this pattern, and otherwise skipped and disabled.

This settings supports regular expression patterns. ^[?].

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.activate-for-ip-address-pattern=...

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    activate-for-ip-address-pattern: "..."

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.activate-for-ip-address-pattern="..." -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_ACTIVATE_FOR_IP_ADDRESS_PATTERN="..."

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.activate-for-ip-address-pattern="..."

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.headers=

Headers, defined as a Map, to include in the request when making the verification call to the recaptcha API.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.headers=...

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    headers: "..."

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.headers="..." -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_HEADERS="..."

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.headers="..."

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.invisible=false

Whether google reCAPTCHA invisible should be enabled.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.invisible=...

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    invisible: "..."

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.invisible="..." -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_INVISIBLE="..."

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.invisible="..."

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.position=bottomright

The google reCAPTCHA badge position (only if invisible is enabled). Accepted values are:

bottomright: bottom right corner, default value.
bottomleft: bottom left corner
inline: allows to control the CSS.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.position=bottomright

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    position: "bottomright"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.position="bottomright" -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_POSITION="bottomright"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.position="bottomright"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.verify-url=https://www.google.com/recaptcha/api/siteverify

The reCAPTCHA endpoint for verification of the reCAPTCHA response. The endpoint is specific to the reCAPTCHA provider:

For Google reCAPTCHA, the endpoint is https://www.google.com/recaptcha/api/siteverify.
For hCaptcha, the endpoint is https://hcaptcha.com/siteverify.
For Turnstile, the endpoint is https://challenges.cloudflare.com/turnstile/v0/siteverify.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.verify-url=https://www.google.com/recaptcha/api/siteverify

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    verify-url: "https://www.google.com/recaptcha/api/siteverify"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.verify-url="https://www.google.com/recaptcha/api/siteverify" -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_VERIFY_URL="https://www.google.com/recaptcha/api/siteverify"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.verify-url="https://www.google.com/recaptcha/api/siteverify"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

cas.google-recaptcha.version=GOOGLE_RECAPTCHA_V2

Indicate the version of the recaptcha api. Available values are as follows:

GOOGLE_RECAPTCHA_V2: V2 version of the recaptcha API.
GOOGLE_RECAPTCHA_V3: V3 version of the recaptcha API.
HCAPTCHA: hCaptcha is an alternative to reCAPTCHA that requires website visitors to label images as part of its business model. The provider is more focused on manual image recognition challenges. It is a image classification task based CAPTCHA provider employing visual challenges like identifying objects.
TURNSTILE: Offers a CAPTCHA alternative by Cloudflare that prioritizes user experience and privacy. Turnstile delivers frustration-free, CAPTCHA-free web experiences to website visitors - with just a simple snippet of free code. Moreover, Turnstile stops abuse and confirms visitors are real without the data privacy concerns or awful user experience of CAPTCHAs.

org.apereo.cas.configuration.model.support.captcha.GoogleRecaptchaProperties.

_{How can I configure this property?}

Configuration properties can be included and activated using the following strategies.

Note

CAS properties can be specified using the Java configuration property syntax in any and all .properties files:

cas.google-recaptcha.version=GOOGLE_RECAPTCHA_V2

CAS properties can be specified using the YAML syntax:

cas: 
  google-recaptcha: 
    version: "GOOGLE_RECAPTCHA_V2"

Note that YAML is very specific about structure and indentation. Be sure to verify the correctness of the final result with your YAML validator of choice.

CAS properties can be passed to the CAS web application as system properties, when the application is launched:

java -Dcas.google-recaptcha.version="GOOGLE_RECAPTCHA_V2" -jar build/libs/cas.war

CAS properties can specified as system environment variables before the CAS web application is launched:

export CAS_GOOGLE_RECAPTCHA_VERSION="GOOGLE_RECAPTCHA_V2"

java -jar build/libs/cas.war

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

CAS properties can be passed to the CAS web application as command-line arguments, when the application is launched:

java -jar build/libs/cas.war --cas.google-recaptcha.version="GOOGLE_RECAPTCHA_V2"

The above example assumes that the CAS web application is packaged as cas.war with an embedded server container and can be found in the build/libs directory.

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.

Note

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.

Use Case

Note that this particular integration applies to login and authentication attempts. Several other CAS modules do also support reCAPTCHA integrations for their own special flows, specially when it comes to reCAPTCHA activation strategies, separate from what is documented and available here.

Internet Explorer

Remember to disable Internet Explorer’s “Compatibility View” mode. reCAPTCHA may not render correctly when that mode is turned on.

reCAPTCHA Per Service

Certain reCAPTCHA settings can be defined on a per-service basis via dedicated properties:

{
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "^https://.+",
  "name" : "sample service",
  "id" : 100,
  "properties" : {
    "@class" : "java.util.HashMap",
    "captchaEnabled" : {
      "@class" : "org.apereo.cas.services.DefaultRegisteredServiceProperty",
      "values" : [ "java.util.HashSet", [ "false" ] ]
    },
    "captchaIPAddressPattern" : {
      "@class" : "org.apereo.cas.services.DefaultRegisteredServiceProperty",
      "values" : [ "java.util.HashSet", [ "pattern1", "pattern2" ] ]
    }
  }
}

The following properties are available and recognized by CAS for various modules and features:

Name	Default Value	Type	Group
`captchaIPAddressPattern`	`true`	`SET`	`RECAPTCHA`
`captchaEnabled`	`true`	`BOOLEAN`	`RECAPTCHA`

Activation Strategy

reCAPTCHA activation strategy is generally controlled via CAS settings. It is also possible to design and inject your own activation strategy into CAS using the following @Bean that would be registered in a @AutoConfiguration class:

@Bean
public CaptchaActivationStrategy captchaActivationStrategy() {
    return new MyCaptchaActivationStrategy();
}

Your configuration class needs to be registered with CAS. See this guide for better details.