# Overview

Source: https://apereo.github.io/cas/development/integration/ADFS-Integration.html

The integration between the CAS Server and ADFS delegates user authentication from CAS Server to ADFS, making CAS Server a WS-Federation client. Claims released from ADFS are made available as attributes to CAS Server, and by extension CAS Clients.

> **Deprecated**
>
> WS-Federation support is deprecated and is scheduled for removal in a future CAS version.

> **Remember**
>
> The functionality described here allows CAS to use ADFS as an external identity provider. If you wish to do the opposite, allowing ADFS to become a CAS client and using CAS as an identity provider, you may take advantage of [SAML2 support in CAS](https://apereo.github.io/cas/development/authentication/Configuring-SAML2-Authentication.html) as one integration option.

Support is enabled by including the following dependency in the WAR overlay:

```groovy
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-wsfederation-webflow"
}
```

You may also need to declare the following repository in your CAS Overlay to be able to resolve dependencies:

```groovy
repositories {
    maven { 
        mavenContent { releasesOnly() }
        url "https://build.shibboleth.net/maven/releases/" 
    }
}
```

> **JCE Requirement**
>
> It's safe to make sure you have the proper JCE bundle installed in your Java environment that is used by CAS, especially if you need to consume encrypted payloads issued by ADFS. Be sure to pick the right version of the JCE for your Java version. Java versions can be detected via the `java -version` command.

## WsFed Configuration

Adjust and provide settings for the ADFS instance, and make sure you have obtained the ADFS signing certificate and made it available to CAS at a location that can be resolved at runtime.

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

- `cas.authn.wsfed[0].attribute-mutator-script.location` (Required; type `Resource`): Path to attribute mutator groovy script that allows one to modify wsfed attributes before establishing a final principal. 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`.
- `cas.authn.wsfed[0].cookie.crypto.encryption.key` (Required; type `String`): The encryption key is a string whose length is defined by the encryption key size setting.
- `cas.authn.wsfed[0].cookie.crypto.signing.key` (Required; type `String`): The signing key is a string whose length is defined by the signing key size setting.
- `cas.authn.wsfed[0].id` (Required; type `String`): Internal identifier for this wsfed configuration. If undefined, the identifier would be auto-generated by CAS itself. In the event that there is more than on CAS server defined in a clustered deployment, this identifier must be statically defined in the configuration.
- `cas.authn.wsfed[0].identity-attribute` (Required; type `String`; default `upn`): The attribute extracted from the assertion and used to construct the CAS principal id.
- `cas.authn.wsfed[0].identity-provider-identifier` (Required; type `String`; default `http://adfs.example.org/adfs/services/trust`): The entity id or the identifier of the Wsfed instance.
- `cas.authn.wsfed[0].identity-provider-url` (Required; type `String`; default `https://adfs.example.org/adfs/ls/`): Wsfed identity provider url.
- `cas.authn.wsfed[0].principal.principal-transformation.groovy.location` (Required; type `Resource`): Transform usernames using a Groovy resource. 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`.
- `cas.authn.wsfed[0].relying-party-identifier` (Required; type `String`; default `urn:cas:localhost`): The identifier for CAS (RP) registered with wsfed.
- `cas.authn.wsfed[0].signing-certificate-resources` (Required; type `String`; default `classpath:adfs-signing.crt`): Locations of signing certificates used to verify assertions. Locations could be specified as static file-system resources(certificates) or they could also be federation XML metadata, either as a URL or an XML file. If federation metadata XML is provided, the signing certificate is extracted from the `IDPSSODescriptor`'s key descriptor that is marked for signing.
- `cas.authn.wsfed[0].attribute-resolver-enabled` (Optional; type `boolean`; default `true`): Whether CAS should enable its own attribute resolution machinery after having received a response from wsfed.
- `cas.authn.wsfed[0].attributes-type` (Optional; type `String`; default `WSFED`): Indicates how attributes should be recorded into the principal object. Useful if you wish to additionally resolve attributes on top of what wsfed provides. Accepted values are `CAS,WSFED,BOTH`.
- `cas.authn.wsfed[0].auto-redirect-type` (Optional; type `DelegationAutoRedirectTypes`; default `SERVER`): Whether CAS should auto redirect to this wsfed instance. Available values are as follows: - `SERVER`: Redirect on the server side, typically making CAS invisible. - `CLIENT`: Redirect on the client side using browser redirects, etc. - `NONE`: Do nothing and let the selection take place manually.
- `cas.authn.wsfed[0].cookie.allowed-ip-addresses-pattern` (Optional; type `String`): A regular expression pattern that indicates the set of allowed IP addresses, when `#isPinToSession()` is configured. In the event that there is a mismatch between the cookie IP address and the current request-provided IP address (i.e. network switches, VPN, etc), the cookie can still be considered valid if the new IP address matches the pattern specified here.
- `cas.authn.wsfed[0].cookie.crypto.alg` (Optional; type `String`; default `A256CBC-HS512`): The signing/encryption algorithm to use.
- `cas.authn.wsfed[0].cookie.crypto.enabled` (Optional; type `boolean`; default `true`): Whether crypto operations are enabled.
- `cas.authn.wsfed[0].cookie.crypto.encryption.key-size` (Optional; type `int`; default `512`): The encryption key size.
- `cas.authn.wsfed[0].cookie.crypto.signing.key-size` (Optional; type `int`; default `512`): The signing key size.
- `cas.authn.wsfed[0].cookie.crypto.strategy-type` (Optional; type `String`; default `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.
- `cas.authn.wsfed[0].cookie.domain` (Optional; type `String`): Cookie domain. Specifies the domain within which this cookie should be presented. The form of the domain name is specified by RFC 2965. A domain name begins with a dot (.foo.com) and means that the cookie is visible to servers in a specified Domain Name System (DNS) zone (for example, www.foo.com, but not a.b.foo.com). By default, cookies are only returned to the server that sent them.
- `cas.authn.wsfed[0].cookie.geo-locate-client-session` (Optional; type `boolean`): When set to `true` and assuming `#isPinToSession()` is also `true`, client sessions (using the client IP address) are geo-located using a geolocation service when/if configured. The resulting session is either pinned to the client geolocation, or the default client address.
- `cas.authn.wsfed[0].cookie.http-only` (Optional; type `boolean`; default `true`): true if this cookie contains the HttpOnly attribute. This means that the cookie should not be accessible to scripting engines, like javascript.
- `cas.authn.wsfed[0].cookie.max-age` (Optional; type `String`; default `-1`): The maximum age of the cookie, specified in seconds. By default, `-1` indicating the cookie will persist until browser shutdown. A positive value indicates that the cookie will expire after that many seconds have passed. Note that the value is the maximum age when the cookie will expire, not the cookie's current age. A negative value means that the cookie is not stored persistently and will be deleted when the Web browser exits. A zero value causes the cookie to be deleted.
- `cas.authn.wsfed[0].cookie.name` (Optional; type `String`): Cookie name. Constructs a cookie with a specified name and value. The name must conform to RFC 2965. That means it can contain only ASCII alphanumeric characters and cannot contain commas, semicolons, or white space or begin with a `$` character. The cookie's name cannot be changed after creation. By default, cookies are created according to the RFC 2965 cookie specification. Cookie names are automatically calculated assigned by CAS at runtime, and there is usually no need to customize the name or assign it a different value unless a special use case warrants the change.
- `cas.authn.wsfed[0].cookie.path` (Optional; type `String`): Cookie path. Specifies a path for the cookie to which the client should return the cookie. The cookie is visible to all the pages in the directory you specify, and all the pages in that directory's subdirectories. A cookie's path must include the servlet that set the cookie, for example, /catalog, which makes the cookie visible to all directories on the server under /catalog. Consult RFC 2965 (available on the Internet) for more information on setting path names for cookies.
- `cas.authn.wsfed[0].cookie.pin-to-session` (Optional; type `boolean`; default `true`): When generating cookie values, determine whether the value should be compounded and signed with the properties of the current session, such as IP address, user-agent, etc. Turning off session pinning is not exactly ideal. This is a barrier to prevent cookie replay attacks. A cookie that was created with an IP given a certain location cannot be replayed back in a different browser with a different IP from a different location. There may however be legitimate reasons to turn it off and relax this after careful reviews, if you intend to support a type of user who intends to switch their IP quite frequently. A classic example is the type of user that is on VPN at the time of login, but decides to resume their work a few hours later off VPN or at a different location.
- `cas.authn.wsfed[0].cookie.same-site-policy` (Optional; type `String`): If a cookie is only intended to be accessed in a first party context, the developer has the option to apply one of settings `SameSite=Lax` or `SameSite=Strict` or `SameSite=None` to prevent external access. To safeguard more websites and their users, the new secure-by-default model assumes all cookies should be protected from external access unless otherwise specified. Developers must use a new cookie setting, `SameSite=None`, to designate cookies for cross-site access. When the `SameSite=None` attribute is present, an additional `Secure` attribute is used so cross-site cookies can only be accessed over HTTPS connections. Accepted values are: - `Lax` - `Strict` - `None` - `Off`: Disable the generation of the SameSite cookie attribute altogether. - Path to a Groovy script that is able to generate the SameSite cookie attribute dynamically. - Fully qualified name of a class that implements `org.apereo.cas.web.cookie.CookieSameSitePolicy`
- `cas.authn.wsfed[0].cookie.secure` (Optional; type `boolean`; default `true`): True if sending this cookie should be restricted to a secure protocol, or false if the it can be sent using any protocol.
- `cas.authn.wsfed[0].encryption-certificate` (Optional; type `String`; default `classpath:certificate.crt`): The path to the public key/certificate used to handle and verify encrypted assertions.
- `cas.authn.wsfed[0].encryption-private-key` (Optional; type `String`; default `classpath:private.key`): The path to the private key used to handle and verify encrypted assertions.
- `cas.authn.wsfed[0].encryption-private-key-password` (Optional; type `String`; default `NONE`): The private key password.
- `cas.authn.wsfed[0].name` (Optional; type `String`): Name of the authentication handler.
- `cas.authn.wsfed[0].order` (Optional; type `int`; default `2147483647`): The order of the authentication handler in the chain.
- `cas.authn.wsfed[0].principal.active-attribute-repository-ids` (Optional; type `String`; default `*`): Activated attribute repository identifiers that should be used for fetching attributes if attribute resolution is enabled. The list here may include identifiers separated by comma.
- `cas.authn.wsfed[0].principal.attribute-repository-selection` (Optional; type `Map<String, String>`): Control the behavior of the attribute repository selection by authentication method or handler. The map here is keyed by the authentication handler name, and the value is the attribute repository identifiers separated by comma. When the authentication handler is executed, the attribute repositories assigned to this handler will be selected to fetch attributes. Note that the resolution engine will always favor attribute repositories assigned to the service definition, if any and as part of its authentication policy, over this global setting.
- `cas.authn.wsfed[0].principal.attribute-resolution-enabled` (Optional; type `TriStateBoolean`; default `UNDEFINED`): Whether attribute repositories should be contacted to fetch person attributes. Defaults to true if not set. Available values are as follows: - `TRUE`: Constant to represent the true state. - `FALSE`: Constant to represent the false state. - `UNDEFINED`: Constant to represent the undefined state.
- `cas.authn.wsfed[0].principal.principal-attribute` (Optional; type `String`): Attribute name to use to indicate the identifier of the principal constructed. If the attribute is blank or has no values, the default principal id will be used determined by the underlying authentication engine. The principal id attribute usually is removed from the collection of attributes collected, though this behavior depends on the schematics of the underlying authentication strategy.
- `cas.authn.wsfed[0].principal.principal-resolution-conflict-strategy` (Optional; type `String`; default `last`): In the event that the principal resolution engine resolves more than one principal, (especially if such principals in the chain have different identifiers), this setting determines strategy by which the principal id would be chosen from the chain. Accepted values are: `last`, `first`.
- `cas.authn.wsfed[0].principal.principal-resolution-failure-fatal` (Optional; type `TriStateBoolean`; default `UNDEFINED`): When true, throws an error back indicating that principal resolution has failed and no principal can be found based on the authentication requirements. Otherwise, logs the condition as an error without raising a catastrophic error. Available values are as follows: - `TRUE`: Constant to represent the true state. - `FALSE`: Constant to represent the false state. - `UNDEFINED`: Constant to represent the undefined state.
- `cas.authn.wsfed[0].principal.principal-transformation.blocking-pattern` (Optional; type `String`): 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.
- `cas.authn.wsfed[0].principal.principal-transformation.case-conversion` (Optional; type `PrincipalTransformationProperties.CaseConversion`; default `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.
- `cas.authn.wsfed[0].principal.principal-transformation.pattern` (Optional; type `String`): 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.
- `cas.authn.wsfed[0].principal.principal-transformation.prefix` (Optional; type `String`): Prefix to add to the principal id prior to authentication.
- `cas.authn.wsfed[0].principal.principal-transformation.suffix` (Optional; type `String`): Suffix to add to the principal id prior to authentication.
- `cas.authn.wsfed[0].principal.return-null` (Optional; type `TriStateBoolean`; default `UNDEFINED`): Return a null principal object if no attributes can be found for the principal. Available values are as follows: - `TRUE`: Constant to represent the true state. - `FALSE`: Constant to represent the false state. - `UNDEFINED`: Constant to represent the undefined state.
- `cas.authn.wsfed[0].principal.use-existing-principal-id` (Optional; type `TriStateBoolean`; default `UNDEFINED`): Uses an existing principal id that may have already been established in order to run person directory queries. This is generally useful in situations where authentication is delegated to an external identity provider and a principal is first established to then query an attribute source. Available values are as follows: - `TRUE`: Constant to represent the true state. - `FALSE`: Constant to represent the false state. - `UNDEFINED`: Constant to represent the undefined state.
- `cas.authn.wsfed[0].tolerance` (Optional; type `String`; default `PT10S`): Tolerance value used to skew assertions to support clock drift.

**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](https://tools.ietf.org/html/rfc7517) of a certain size for the key, you are to use the following set of commands to generate the token:

```bash
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:

```json
{
  "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.

---

**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](https://apereo.github.io/cas/development/integration/Apache-Groovy-Scripting.html) to configure your build.

**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:

```groovy
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](https://apereo.github.io/cas/development//integration/Apache-Groovy-Scripting.html).

## Signed Assertions

CAS is able to ascertain the validity of assertion signatures using dedicated certificate files that are defined via CAS settings. Certificate files and resources may be defined statically as file-system resources that are available to CAS to load and use, or the signing resource may point to ADFS federation metadata (either as a URL or XML file). When using the federation metadata, the signing certificate is extracted from the `IDPSSODescriptor` key descriptor that is marked for signing.

## Encrypted Assertions

CAS is able to automatically decrypt SAML assertions that are issued by ADFS. To do this, you will first need to generate a private/public keypair:

```bash
openssl genrsa -out private.key 1024
openssl rsa -pubout -in private.key -out public.key -inform PEM -outform DER
openssl pkcs8 -topk8 -inform PEM -outform DER -nocrypt -in private.key -out private.p8
openssl req -new -x509 -key private.key -out x509.pem -days 365

# convert the X509 certificate to DER format
openssl x509 -outform der -in x509.pem -out certificate.crt
```

Configure CAS to reference the keypair, and configure the relying party trust settings in ADFS to use the `certificate.crt` file for encryption.

## Modifying ADFS Claims

The WsFed configuration optionally may allow you to manipulate claims coming from ADFS but before they are inserted into the CAS user principal. The manipulation of the attributes is carried out using an *attribute mutator* where its logic may be implemented inside a Groovy script and whose path is taught to CAS via settings.

The script may take on the following form:

```groovy
import org.apereo.cas.*
import java.util.*
import org.apereo.cas.authentication.*

Map run(final Object... args) {
    def (attributes,logger) = args
    logger.warn("Mutating attributes {}", attributes)
    return [upn: ["CASUser"]]
}
```

The parameters passed to the script are as follows:

| Parameter | Description |
| --- | --- |
| `attributes` | A current `Map` of attributes provided from ADFS. |
| `logger` | The object responsible for issuing log messages such as `logger.info(...)`. |

Note that the execution result of the script *MUST* ensure that attributes are collected into a `Map` where the attribute name, the key, is a simple `String` and the attribute value is transformed into a collection.

To prepare CAS to support and integrate with Apache Groovy, please [review this guide](https://apereo.github.io/cas/development/integration/Apache-Groovy-Scripting.html).

## Handling CAS Logout

An optional step, the `casLogoutView.html` can be modified to place a link to ADFS’s logout page.

```html
<a href="https://adfs.example.org/adfs/ls/?wa=wsignout1.0">Logout</a>
```

Alternatively, you may instruct CAS to redirect to the above endpoint after logout operations have executed.

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

- `cas.logout.confirm-logout` (Optional; type `Boolean`; default `false`): Before logout, allow the option to confirm on the web interface.
- `cas.logout.follow-service-redirects` (Optional; type `Boolean`; default `false`): Whether CAS should be allowed to redirect to an alternative location after logout.
- `cas.logout.redirect-parameter` (Optional; type `List<String>`): The target destination to which CAS should redirect after logout is indicated and extracted by a parameter name of your choosing here. If none specified, the default will be used as `service`.
- `cas.logout.redirect-url` (Optional; type `String`): A url to which CAS must immediately redirect after all logout operations have completed. Typically useful in scenarios where CAS is acting as a proxy and needs to redirect to an external identity provider's logout endpoint in order to remove a session, etc.

## Per-Service Relying Party Id

In order to specify a relying party identifier per service definition, adjust your service registry to match the following:

```json
{
  "@class" : "org.apereo.cas.services.CasRegisteredService",
  "serviceId" : "^https://.+",
  "name" : "sample service",
  "id" : 100,
  "properties" : {
    "@class" : "java.util.HashMap",
    "wsfed.relyingPartyIdentifier" : {
      "@class" : "org.apereo.cas.services.DefaultRegisteredServiceProperty",
      "values" : [ "java.util.HashSet", [ "custom-identifier" ] ]
    }
  }
}
```

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

| Name | Default Value | Type | Group |
| --- | --- | --- | --- |
| `wsfed.relyingPartyIdentifier` |  | `STRING` | `DELEGATED_AUTHN_WSFED` |

## Troubleshooting

Be aware of clock drift issues between CAS and the ADFS server. Validation failures of the response do show up in the logs, and the request is routed back to ADFS again, causing redirect loops.

To enable additional logging, configure the log4j configuration file to add the following levels:

```xml
...
<Logger name="org.apereo.cas.support.wsfederation" level="debug" additivity="false">
    <AppenderRef ref="casConsole"/>
    <AppenderRef ref="casFile"/>
</Logger>
...
```