# Performing a WS-Trust login request Create a WS-Trust login request using the metadata exchange data (MEX) response. ## Discussion After receiving a WS-Trust MEX response, the next step that the system performs for federated authentication with WS-Trust, meaning between security domains, is to send a login request to a federated identity provider (IdP). The system uses the [`federationRequestURN`](/documentation/AuthenticationServices/ASAuthorizationProviderExtensionLoginConfiguration/federationRequestURN) and the URLs specified in the MEX response to create the WS-Trust login request, per Web Services Security Username Token Profile Version 1.1.1. The system doesn’t support `PasswordDigest`. The system sends the WS-Trust login using Simple Object Access Protocol (SOAP) to the endpoint in the MEX response. For more information about federated authentication with WS-Trust, see [Authentication process](/documentation/AuthenticationServices/authentication-process). ### Receive the WS-Trust login response The system loads the SOAP response as XML and validates it, which includes checking that the nonce is correct and the created and expires dates are current. The system then parses the `TokenType` and uses it to set the correct `grant_type` in the Platform SSO login request. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)