Auto populating j_username using username/password authentication

[Mr. Christopher Bland]

Hi All,

I have been tasked with authenticating Azure AD (cloud only) accounts and on premise AD accounts with the same domain name (@contoso.com) in Office 365.  At present thanks to the great Microsoft Interop docs I have Office365, AD, and Shibboleth working together.  My plan is to deploy a SP with lazy session so I can detect existing session and forward authenticated users accordingly. For unauthenticated users => collect username using a php form local to the SP => Check to see if they are an AD or Azure AD account using Graph API calls (still working on the Graph API authentication portion) => Redirect on prem AD accounts to Office365 using IDP inititated session.

Due to the fact that I need to capture the username for my decision based logic I don’t want to prompt the user to enter the username a second time.  So I am trying to figure out how to pass it as part of my IDP initiated session URL.  I looked at previous posts and it looks like this has been done but it is unclear how.

Also if anyone has solved a problem like the the one I am working with I would appreciate feedback.  At the moment this is a theoretical solution.  I am working on proof of concept.

-Chris