I am looking at a use case where the service provider will need to capture the user id (not password) to identify the target IDP. In this case, the requirement is to send the user id (that is already captured at service provider end) to IDP, so that IDP can pre-populate the user ID while asking for password to end user.

Is there a standard in SAML how this information can be passed from SP to IDP? I am using SP initiated SAML where SAMLRequest and RelayState will be passed from SP to IDP.

Thank you.

2 Answers 2


Yes, the SP can send a user id to the Idp as part of the AuthnRequest by including a <saml:Subject> element.


In SAML environments, this task (finding out the appropriate IDP) is solved in a different way: There is another indirection to a discovery service where the user chooses the IDP manually by clicking on it. The service provider has no knowledge about which user belongs to which IDP.

  • 1
    Hi, thanks for your response. But my query is somewhat driven by the requirement where end user does not need to do anything specific and should not need to provide the username twice. Commented Jun 27, 2016 at 6:08

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .