Web API using windows authentication + Xamarin Client

Hi all,

I'm working on an android application and I need to make sure the user is connected, so our manager wants to use the active directory to verify if the right user is connected. So I created a web api that uses windows auth and from my android app I sen a webrequest with the username and compare it with the AD... All that is through VPN

The problem is on my android app when I send the webrequest I get this error: {System.Net.WebException: The remote server returned an error: (401) Unauthorized. This happends because the web api requires a login and password when we access it....

My question is: is there a solution to keep using the AD from the android app? Any ideas how?

Thanks,