title: Authenticate Azure AD v1 WebAPI from Azure AD v2 mobile app
body: <p>We have a Xamarin forms mobile app where users are authenticated by AAD v2 endpoint (MSAL - Microsoft.Identity.Client) and an ASP.NET Web API application where the same users are authenticated by AAD v1 endpoint (ADAL - Microsoft.IdentityModel.Clients.ActiveDirectory). </p>
  
  <p>We would like to have REST calls authenticated in the Web API from the mobile app. We've tried passing v2 authentication tokens but get InvalidAuthenticationToken returned to us.</p>
  
  <p>First of all not sure if it is actually possible. <a href="https://www.youtube.com/watch?v=BcSdX9p92Pk" rel="nofollow noreferrer">This MS presentation from 2017</a> says that it hasn't been implemented 'yet', but can't find whether it is now possible. Failing that, is there some other way to get this to work?</p>
  
  <p>Thanks</p>