title: Angular & Asp.Net Core - Enable 2 Factor Authentication
body: <p>I have a single page application written in angular 7 which communicates with my ASP.Net Core 2.2 Web API server. 
  On login, the user sends his credentials to my authorization server (connect/token) using "resource owner password credentials" grant. 
  I am trying to add 2-factor authentication (SMS), but I can't find any example describing how to do this. All the examples I found were written with MVC using cookies authentication. </p>
  
  <p>I was thinking about this flow but it feels to me there should be a much better way</p>
  
  <ol>
  <li>A user enters his user name &amp; password</li>
  <li>If the user has 2 factors enabled I will send him an SMS with a code. In addition, a limited access_token and id token will be sent to the client. this access_token will be valid only to enable the user to send the 2-factor code.
  if id-token will have a claim for 'two factors': 'on', I will redirect the user to an SMS confirmations code.</li>
  <li>The user will send a post request with the code. If the code matche, I will return to the client a new access_token with all the claims.</li>
  </ol>