Passwordless Authentication

Passwordless Authentication is a form of authentication in CAS where passwords take the form of tokens that expire after a configurable period of time. Using this strategy, users are asked for an identifier (i.e. username) which is used to locate the user record that contains forms of contact such as email and phone number. Once located, the CAS-generated token is sent to the user via the configured notification strategies (i.e. email, sms, etc) where the user is then expected to provide the token back to CAS in order to proceed.

:information_source: No Magic Link

Presently, there is no support for magic links that would remove the task of providing the token back to CAS allowing the user to proceed automagically. This variant may be worked out in future releases.

In order to successfully implement this feature, configuration needs to be in place to contact account stores that hold user records who qualify for passwordless authentication. Similarly, CAS must be configured to manage issued tokens in order to execute find, validate, expire or save operations in appropriate data stores.

Qualifying passwordless accounts may also directly be routed to selected multifactor authentication providers or delegated to external identity providers for further verification.

Passwordless Variants

Passwordless authentication can also be activated using QR Code Authentication, allowing end users to login by scanning a QR code using a mobile device.

Passwordless authentication can also be achieved via FIDO2 WebAuthn which lets users verify their identities without passwords and login using FIDO2-enabled devices.

Overview

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



1
2
3
4
5



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





1



implementation "org.apereo.cas:cas-server-support-passwordless-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-passwordless-webflow"
}





1
2
3
4
5
6
7
8
9
10



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-passwordless-webflow"
}

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.passwordless.core.delegated-authentication-selector-script.location=

    • 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, specially if the script 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.

    org.apereo.cas.configuration.model.SpringResourceProperties.

    How can I configure this property?

    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.authn.passwordless.core.delegated-authentication-activated=false

    • Allow passwordless authentication to skip its own flow in favor of delegated authentication providers that may be available and defined in CAS.

    If delegated authentication is activated, CAS will skip its normal passwordless authentication flow in favor of the requested delegated authentication provider. If no delegated providers are available, passwordless authentication flow will commence as usual.

    org.apereo.cas.configuration.model.support.passwordless.PasswordlessAuthenticationCoreProperties.

    How can I configure this property?

  • cas.authn.passwordless.core.enabled=true

    • Flag to indicate if paswordless authentication is enabled.

    org.apereo.cas.configuration.model.support.passwordless.PasswordlessAuthenticationCoreProperties.

    How can I configure this property?

  • cas.authn.passwordless.core.multifactor-authentication-activated=false

    • Allow passwordless authentication to skip its own flow in favor of multifactor authentication providers that may be available and defined in CAS.

    If multifactor authentication is activated, and defined MFA triggers in CAS signal availability and eligibility of an MFA flow for the given passwordless user, CAS will skip its normal passwordless authentication flow in favor of the requested multifactor authentication provider. If no MFA providers are available, or if no triggers require MFA for the verified passwordless user, passwordless authentication flow will commence as usual.

    org.apereo.cas.configuration.model.support.passwordless.PasswordlessAuthenticationCoreProperties.

    How can I configure this property?

    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, 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.

    Account Stores

    User records that qualify for passwordless authentication must be found by CAS using one of the following strategies. All strategies may be configured using CAS settings and are activated depending on the presence of configuration values.

    Option Description
    Simple Please see this guide.
    MongoDb Please see this guide.
    LDAP Please see this guide.
    JSON Please see this guide.
    Groovy Please see this guide.
    REST Please see this guide.
    Custom Please see this guide.
    Duo Security Please see this guide.

    Note that Multiple passwordless account stores can be used simultaneously to verify and locate passwordless accounts.

    Token Management

    The following strategies define how issued tokens may be managed by CAS.

    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.passwordless.tokens.crypto.encryption.key=

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

    This setting supports the Spring Expression Language.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.signing.key=

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

    This setting supports the Spring Expression Language.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

    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.authn.passwordless.tokens.crypto.alg=

    • The signing/encryption algorithm to use.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.enabled=true

    • Whether crypto operations are enabled.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.encryption.key-size=512

    • The encryption key size.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.signing.key-size=512

    • The signing key size.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.strategy-type=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.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.core.expiration=PT180S

    • Indicate how long should the token be considered valid.

    This settings supports the java.time.Duration syntax [?].

    org.apereo.cas.configuration.model.support.passwordless.token.PasswordlessAuthenticationTokensCoreProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.encryption.key=

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

    This setting supports the Spring Expression Language.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.signing.key=

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

    This setting supports the Spring Expression Language.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.alg=

    • The signing/encryption algorithm to use.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.enabled=true

    • Whether crypto operations are enabled.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.encryption.key-size=512

    • The encryption key size.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.signing.key-size=512

    • The signing key size.

    org.apereo.cas.configuration.model.core.util.SigningJwtCryptoProperties.

    How can I configure this property?

  • cas.authn.passwordless.tokens.crypto.strategy-type=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.

    org.apereo.cas.configuration.model.core.util.EncryptionJwtSigningJwtCryptographyProperties.

    How can I configure this property?

    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.

    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, 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.

    Option Description
    Memory This is the default option where tokens are kept in memory using a cache with a configurable expiration period.
    MongoDb Please see this guide.
    JPA Please see this guide.
    REST Please see this guide.
    Custom Please see this guide.

    Messaging & Notifications

    Please see this for details.

    Disabling Passwordless Authentication Flow

    Passwordless authentication can be disabled conditionally on a per-user basis. If the passwordless account retrieved from the account store carries a user whose requestPassword is set to true, the passwordless flow (i.e. as described above with token generation, etc) will be disabled and skipped in favor of the more usual CAS authentication flow, challenging the user for a password. Support for this behavior may depend on each individual account store implementation.

    Passwordless Authentication Per Application

    Passwordless authentication can be selectively controlled for specific applications. By default, all services and applications are eligible for passwordless authentication.

    

    1
2
3
4
5
6
7
8
9
10

    		

    {
  "@class": "org.apereo.cas.services.CasRegisteredService",
  "serviceId": "^https://app.example.org",
  "name": "App",
  "id": 1,
  "passwordlessPolicy" : {
    "@class" : "org.apereo.cas.services.DefaultRegisteredServicePasswordlessPolicy",
    "enabled": false
  }
}

    The following passwordless policy settings are supported:

    Name Description
    enabled Boolean to define whether passwordless authentication is allowed for this service.