title: How to acquire a user based token from Azure Graph API
body: <p>I have an Azure Active Directory and in my Web Api I have a piece of code that I can get a token from Azure Graph Api using the Application that I have registered with Azure and a Client Certificate.
  Here is the code that I use right now:</p>
  
  <pre><code>public static string AcquireServiceToken()
  {
      var authority = string.Format(_authority, "common");
      var authContext = new AuthenticationContext(authority);
  
      var result = authContext.AcquireToken(_serviceTokenResourceId, new ClientAssertionCertificate(_serviceTokenClientId, GetClientCertificate(_certThumbprint)));
      return result.AccessToken;
  }
  </code></pre>
  
  <p>This snippet of code works just fine, now what I need is a more specific token which has logged-in user's context, so basically I need to be able to pass in a username and password and get a Graph token back from Azure.
  Any Ideas?</p>