Hi Aarom,
Thanks for posting here.
NPS does not have a built-in method could allow us to do authentication in this way .
We may consider to develop our own software with using Windows Radius API or go to search third party Windows platform based solution. Solution that will help to do
in this way.
http://technet.microsoft.com/en-us/library/dd197535(WS.10).aspx
Thanks.
Tiger Li
Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.