APEREO CASDocumentation

Enterprise Authentication for All Earthlings and Beyond

Identity, Single Sign-On and Access Management
View on GitHub

Attribute Consent

CAS provides the ability to enforce user-informed consent upon attribute release. Practically, this means that prior to accessing the target application, the user will be presented with a collection of attributes allowed to be released to the application with options to either proceed or deny the release of said attributes. There are also additional options to indicate how should underlying changes in the attribute release policy be considered by the consent engine. Users are also provided the ability to set up reminders in the event that no change is detected in the attribute release policy.

Consent attribute records stored in the configured repository are signed and encrypted. Every CAS node must share the same keys. A record that can no longer be deciphered, because the keys were rotated or because a node does not have them, counts as a mismatch: the user is asked to consent again and the record is replaced with one that is encoded using the current keys.

Consent decisions record their creation date in UTC, and reminders are calculated in UTC. This keeps a decision’s age the same on every CAS node, whatever time zone each node runs in. Dates presented back to the user, such as those on the account profile screen, are shown in UTC as well.

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



1
2
3
4
5



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





1



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





1
2
3
4
5
6
7
8
9



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

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





1
2
3
4
5
6
7
8
9
10



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-consent-webflow"
}

Configuration

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

cas.consent.core.crypto.encryption.keyThe encryption key is a string whose length is defined by the encryption key size setting.
no default
RequiredSpEL

The encryption key is a string whose length is defined by the encryption key size setting.

Type
String
Default
none
Defined by
EncryptionJwtCryptoProperties
Supports
Spring Expression Language
cas.consent.core.crypto.signing.keyThe signing key is a string whose length is defined by the signing key size setting.
no default
RequiredSpEL

The signing key is a string whose length is defined by the signing key size setting.

Type
String
Default
none
Defined by
SigningJwtCryptoProperties
Supports
Spring Expression Language
cas.consent.core.activeWhether consent functionality should be globally applicable to all applications and requests.
true

Whether consent functionality should be globally applicable to all applications and requests.

Type
Boolean
Default
true
Defined by
ConsentCoreProperties
cas.consent.core.crypto.algThe signing/encryption algorithm to use.
no default

The signing/encryption algorithm to use.

Type
String
Default
none
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.consent.core.crypto.enabledWhether crypto operations are enabled.
true

Whether crypto operations are enabled.

Type
Boolean
Default
true
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.consent.core.crypto.encryption.key-sizeThe encryption key size.
512

The encryption key size.

Type
Integer
Default
512
Defined by
EncryptionJwtCryptoProperties
cas.consent.core.crypto.signing.key-sizeThe signing key size.
512

The signing key size.

Type
Integer
Default
512
Defined by
SigningJwtCryptoProperties
cas.consent.core.crypto.strategy-typeControl the cipher sequence of operations.
ENCRYPT_AND_SIGN
Control the cipher sequence of operations. The accepted values are:
  • ENCRYPT_AND_SIGN: Encrypt the value first, and then sign.
  • SIGN_AND_ENCRYPT: Sign the value first, and then encrypt.
Type
String
Default
ENCRYPT_AND_SIGN
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.consent.core.enabledWhether consent functionality should be enabled.
true

Whether consent functionality should be enabled.

Type
Boolean
Default
true
Defined by
ConsentCoreProperties
cas.consent.core.excluded-attributesAttributes that should always and globally be excluded from the list of consentable attributes.
no default

Attributes that should always and globally be excluded from the list of consentable attributes. Such attributes are always ignored during consent rule calculations and users will not be prompted to consent to their release..

Type
List<String>
Default
none
Defined by
ConsentCoreProperties
cas.consent.core.reminderGlobal reminder time unit, to reconfirm consent in cases no changes are detected.
30

Global reminder time unit, to reconfirm consent in cases no changes are detected.

Type
Long
Default
30
Defined by
ConsentCoreProperties
cas.consent.core.reminder-time-unitGlobal reminder time unit of measure, to reconfirm consent in cases no changes are detected.
days

Global reminder time unit of measure, to reconfirm consent in cases no changes are detected.

Type
ChronoUnit
Default
days
Defined by
ConsentCoreProperties
cas.consent.core.webflow.enabledWhether webflow auto-configuration should be enabled.
true

Whether webflow auto-configuration should be enabled.

Type
Boolean
Default
true
Defined by
WebflowAutoConfigurationProperties
cas.consent.core.webflow.orderThe order in which the webflow is configured.
0

The order in which the webflow is configured.

Type
Integer
Default
0
Defined by
WebflowAutoConfigurationProperties

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.

Signing & encryption

This CAS feature is able to accept signing and encryption crypto keys. In most scenarios if keys are not provided, CAS will auto-generate them. The following instructions apply if you wish to manually and beforehand create the signing and encryption keys.

Note that if you are asked to create a JWK of a certain size for the key, you are to use the following set of commands to generate the token:



1
2



wget https://raw.githubusercontent.com/apereo/cas/master/etc/jwk-gen.jar
java -jar jwk-gen.jar -t oct -s [size]

The outcome would be similar to:



1
2
3
4
5



{
  "kty": "oct",
  "kid": "...",
  "k": "..."
}

The generated value for k needs to be assigned to the relevant CAS settings. Note that keys generated via the above algorithm are processed by CAS using the Advanced Encryption Standard (AES) algorithm which is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology.

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:

attributeConsent
CAS endpoint6 operationsNot exposed by default
base path /cas/actuator/
1

Turn the endpoint on and expose it over the web. One entry covers every operation. By default only info, health and status are exposed.



1
2



management.endpoint.attributeConsent.access=UNRESTRICTED
management.endpoints.web.exposure.include=attributeConsent

Endpoints may be mapped to other paths. For example, to serve health at healthcheck:



1



management.endpoints.web.path-mapping.health=healthcheck

Account Profile Management

The attribute consent feature is able to provide consent decision records and information to the account profile management feature in CAS. See this guide for better details.

Attribute Selection

By default, all attributes that are marked for release do qualify for consent. To control this process, you may define a consent policy that indicates a criteria by which attribute selection for consent is carried out.

The policy assigned to each service includes the following features:

Field Description
excludedAttributes Optional. Exclude the indicated attributes from consent.
includeOnlyAttributes Optional. Force-include the indicated attributes in consent, provided attributes are resolved.
excludedServices Optional. Set of service identifiers, defined as a regular expression, for which consent should be skipped. Particularly useful if the service definition is treated as an aggregate of many other applications, allowing this to act as an inner filter.
status Controls whether consent for this service should be activated. See below for activation rules.

A sample definition follows:



1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17



{
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "sample",
  "name" : "sample",
  "id" : 100,
  "description" : "sample",
  "attributeReleasePolicy" : {
    "@class" : "org.apereo.cas.services.ReturnAllAttributeReleasePolicy",
    "consentPolicy": {
      "@class": "org.apereo.cas.services.consent.DefaultRegisteredServiceConsentPolicy",
      "excludedAttributes": ["java.util.LinkedHashSet", ["test"]],
      "includeOnlyAttributes": ["java.util.LinkedHashSet", ["test"]],
      "excludedServices": ["java.util.LinkedHashSet", ["https://example.*"]],
      "status": "FALSE"
    }
  }
}

Activation

See this guide for more details.

Storage

User consent decisions may be stored and remembered using one of the following options.

Storage Description
DynamoDb See this guide.
Groovy See this guide.
JDBC See this guide.
JSON See this guide.
LDAP See this guide.
MongoDb See this guide.
Redis See this guide.
REST See this guide.
Custom See this guide.

Multitenancy

Configuration settings for attribute consent storage can be specified in a multitenant environment. For example, one tenant may choose to store consent decisions in MongoDb, while another tenant may choose to use a SQL database.

:information_source: Remember

Not every attribute consent storage service is multitenant-aware, and this capability is limited to CAS features and modules that are explicitly designed to support multitenancy. Please verify with the specific documentation for your storage service of choice.

Please review this guide for more information on multitenancy.