title: Use Active Directory with Web API for SPA
body: <p>I am building single page application and I would like to know user's identity. We have Active Directory in our intranet but I don't know much about it. I am able to use code like this to verify username and password.</p>
  
  <pre><code>using(PrincipalContext pc = new PrincipalContext(ContextType.Domain, "YOURDOMAIN"))
  {
    bool isValid = pc.ValidateCredentials("myuser", "mypassword");
  }
  </code></pre>
  
  <p>In fact that is everything I need from the Active Directory side of thing. So I could create some AuthorizationFilter with this code but this would mean that username and password must be in every request. I would like to send username and password only once and then use some token for authorization. So there should be some token provider inside my server-side application.</p>
  
  <p>I am building this application from scratch so I can use the latest .net technologies. I found that there are some Owin middlewares which are handling tokens, cookies and OAuth. Could anything of that help me?</p>