Configuring single sign-on (SSO) partners

Before you begin

This task assumes that you have enabled the SAML Web SSO feature.

About this task

Before you can use the WebSphere Application Server as a service provider partner to identity providers for IdP-initiated single sign-on, you need to establish partnerships between the WebSphere Application Server SAML service provider and external SAML identity providers.

Procedure

Add an identity provider to the WebSphere Application Server SAML service provider for single sign-on.
To use the WebSphere Application Server SAML service provider for single sign-on with an identity provider, you need to add the identity provider as a partner. Three equivalent procedures are described here:
- Add an identity provider using metadata of the identity provider.
- Import the SAML token signer certificate using the administrative console.
- Import the SAML token signer certificate using the wsadmin command-line utility.
Pick the procedure you want to use and follow the steps under its underlined heading:
- Add an identity provider using metadata of the identity provider.
1. Start the WebSphere Application Server.
2. Start the wsadmin command-line utility from the app_server_root/bin directory by entering the command: wsadmin -lang jython.
3. At the wsadmin prompt, enter the following command: AdminTask.importSAMLIdpMetadata('-idpMetadataFileName <IdPMetaDataFile> -idpId 1 -ssoId 1 -signingCertAlias <idpAlias>') where IdpMetaDataFile is the full path name of the IdP metadata file, and IdpAlias is any alias name that you specify for the imported certificate.
  
  Note:
  If you encounter an error when running the importSAMLIdpMetadata admin task that you cannot get past, such as a com.ibm.websphere.management.cmdframework.CommandException or schema error, you cannot use the importSAMLIdpMetadata admin task to add the identity provider information to the SAML TAI configuration. Skip to Extract the SAML token signer certificate from the IdP metadata file and perform the described procedure.
4. Save the configuration by entering the following command: AdminConfig.save().
5. Exit the wsadmin command utility by entering the following command: quit.
6. Restart the WebSphere Application Server.
- Extract the SAML token signer certificate from the IdP metadata file
1. Bring up the IdP metadata file in an editor.
2. Find the section in the metadata file from which to extract the X509Certificate:
  - Search the file for IDPSSODescriptor.
    1. From that location, search forward for KeyDescriptor use="signing".
      
      If you don't find KeyDescriptor with use="signing", go to the only KeyDescriptor in that section.
    2. From that location, search forward for X509Certificate.
  - If you don't find IDPSSODescriptor, go to the beginning of the file, then search for the Signature. The easiest way to do that is to search for SignedInfo>.
    - From that location, search forward for X509Certificate
3. Create an IdP.crt file that contains the SAML token signer certificate:
  1. Create a new file called IdP.crt with the following contents:
```
-----BEGIN CERTIFICATE-----
-----END CERTIFICATE-----
```
  2. Copy the value of the X509Certificate element that you located in the metadata file, then paste it between the two lines in the IdP.crt file. For example:
```
-----BEGIN CERTIFICATE-----
MIIE4jBBAs6gAgIBAgIQOw4....
-----END CERTIFICATE-----
```
  3. Save the IdP.crt file.
4. Manually add the identity provider's SAML token signer certificate to the trust store using the IdP.crt file.
  Perform one of the procedures described under Manually add an identity provider to the WebSphere Application Server SAML service provider.
- Manually add an identity provider to the WebSphere Application Server SAML service provider.
  The minimum requirement to configure the WebSphere Application Server SAML service provider as an SSO partner to an identity provider is to import the SAML token signer certificate from the identity provider to the trust store of the service provider. The service provider can be configured to work with multiple identity providers. For each identity provider, you must import the SAML token signer certificate.
  
  You can import the certificate used by an IdP to sign the SAML token by using either the administrative console or the wsadmin command-line utility.
- Import the SAML token signer certificate using the administrative console.
1. Log on to the WebSphere Application Server administrative console.
2. Click Security > SSL certificate and key management > Key stores and certificates > NodeDefaultTrustStore > Signer certificates.
  Use CellDefaultTrustStore instead of NodeDefaultTrustStore for a deployment manager.
3. Click Add.
4. Fill in the certificate information.
5. Click Apply.
- Import the SAML token signer certificate using the wsadmin command-line utility.
1. Start the WebSphere Application Server.
2. Start the wsadmin command-line utility from the app_server_root/bin directory by entering the command: wsadmin -lang jython.
3. At the wsadmin prompt, enter the following command: AdminTask.addSignerCertificate('[-keyStoreName NodeDefaultTrustStore -certificateFilePath <certFile> -base64Encoded true -certificateAlias <certAlias>]') where certFile is the full path name of the certificate file and certAlias is the alias of the certificate.
  Use CellDefaultTrustStore instead of NodeDefaultTrustStore for a deployment manager.
4. Save the configuration by entering the following command: AdminConfig.save().
5. Exit the wsadmin command utility by entering the following command: quit.
Make your application trust your Identity provider's realm. Perform one of the following actions:
1. If your application does not require knowledge of the original realm name, you can hardcode the realm name that the SAML TAI specifies for core security to use while creating the subject.
  1. Click Security > Global Security.
  2. Under User account repository, get the realm name from the Realm name field.
  3. Set the sso_<id>.sp.useRealm OIDC TAI property to the realm name acquired in the previous step.
2. If your application must have access to the original realm name in the Subject, perform the following actions.
  Add IdP realms to the list of inbound trusted realms.
  For each Identity provider that is used with your WebSphere Application Server service provider, you must grant inbound trust to all the realms that are used by the identity provider.
  You can grant inbound trust to the identity providers using either the administrative console or the wsadmin command utility.
  - Add inbound trust using the administrative console.
  1. Click Global security.
  2. Under user account repository, click Configure.
  3. Click Trusted authentication realms - inbound.
  4. Click Add External Realm.
  5. Click OK and Save changes to the master configuration.
  Add inbound trust using the wsadmin command-line utility.
1. To add a single identity provider to the inbound trust, use the following command: AdminTask.addTrustedRealms('[-communicationType inbound -realmList <realmName>]') where realmName is the name of the realm that needs to be granted inbound trust.
2. To add a list of realms to the inbound trust, use the following command: AdminTask.addTrustedRealms('[-communicationType inbound -realmList <realm1|realm2|realm3>]') where realm1, realm2, and realm3 are the realms that need to be added as trusted realms.
Fill in the external realm name.
Add the WebSphere Application Server SAML service provider to the identity providers for SSO.
Each identity provider that is used with your WebSphere Application Server service provider needs to be configured to add the service provider as an SSO partner. The procedure for adding the service provider partner to an identity provider depends on the specific identity provider. Refer to the documentation of the identity provider for instructions on how to add a service provider partner for SSO.

You can either export the WebSphere Application Server service provider metadata, and import it to the identity provider, or manually configure the identity provider to add the service provider.

To add the service provider as a federation partner to an identity provider, you must provide the URL of the Assertion Consumer Service (ACS) of the service provider, which is the -acsUrl parameter used when enabling the SAML trust association interceptor (TAI).
If an identity provider can use a metadata file to add the service provider as a federation partner, you can use the following wsadmin command-line utility command to export the service provider metadata:
```
wsadmin -lang jython
AdminTask.exportSAMLSpMetadata('-spMetadataFileName /tmp/spdata.xml -ssoId 1')
```
This command creates the /tmp/spdata.xml metadata file.
If the SAML token is encrypted, you must provide the public key certificate that you want the identity provider to use for encrypting the SAML token, and the certificate must exist in the WebSphere Application Server default KeyStore before performing an export.
Configure the WebSphere Application Server security context using the sso_<id>.sp.idMap,sso_<id>.sp.groupMap, and sso_<id>.sp.groupName attributes.
The WebSphere Application Server service provider intercepts a SAML protocol message from the identity provider and establishes the security context. The security context is created by mapping the SAML assertion. The security context mapping in the service provider is very flexible and configurable. The following is a list of available mapping options:
- idAssertion
  You can map the SAML assertion to the WebSphere Application Server platform Subject without using a local registry and this is the default behavior. In this default implementation, the SAML NameID is mapped to the principal, the issuer is mapped to the realm, and selected attributes can be mapped to group members. ID assertion can be further customized. For example, you can configure a SAML attribute as a principal, realm, accessId, or a list of group members. You can also configure NameQualifier from NameID as a realm, or use a predefined realm name.
- localRealm
  You can configure the WebSphere Application Server service provider to map the NameID from a SAML assertion to the local registry of the service provider, and build the subject from the registry. With this option, you can directly search the SAML NameID against the registry, or use a plugin point for custom mapping of the assertion, and then use the new mapped ID to build the subject from the registry.
- localRealmThenAssertion
  This option allows you to map the NameID to the registry, and fall back to ID assertion if the NameID cannot be mapped to the registry.
- AddGroupsFromLocalRealm
  This option combines ID assertion and local registry and allows you to reevaluate group membership while doing ID assertion. Consider a SAML assertion from a partner lab, containing user Joe with a group attribute of X-ray Techs. At the service provider, the group X-ray Techs is a subgroup of group Technicians, but Joe is not necessarily in the user registry of the service provider. The authorization policy of the service provider application allows access to the Technicians group. To achieve this, the SAML TAI needs to look up the asserted groups X-ray Techs in the registry and then include the parent groups Technicians in the Subject.
When doing ID assertion to create a security context, a custom security realm is chosen. You must explicitly add the custom realm as a trusted realm. In a default ID assertion implementation, the SAML issuer name is used as the security realm. You must explicitly add the issuer name to the list of inbound trusted authentication realms in current user registry. After adding the custom realm to the inbound trusted realms, you are ready to do role mapping with this custom realm.

To add a custom realm as a trusted realm, see the Add IdP realms to the list of inbound trusted realms step.

Results

Your WebSphere Application Server is now configured as a service provider partner for IdP-initiated SSO.

What to do next

For additional configuration options for your service provider, see the SAML web SSO TAI custom properties topics for a complete list of SAML TAI custom properties.