Get IPrincipal from OAuth Bearer Token in OWIN

I found a part of the solution in this blog post: http://leastprivilege.com/2013/10/31/retrieving-bearer-tokens-from-alternative-locations-in-katanaowin/

So I created my own Provider as follows:

public class QueryStringOAuthBearerProvider : OAuthBearerAuthenticationProvider
{
    public override Task RequestToken(OAuthRequestTokenContext context)
    {
        var value = context.Request.Query.Get("access_token");

        if (!string.IsNullOrEmpty(value))
        {
            context.Token = value;
        }

        return Task.FromResult<object>(null);
    }
}

Then I needed to add it to my App in Startup.Auth.cs like this:

OAuthBearerOptions = new OAuthBearerAuthenticationOptions()
{
   Provider = new QueryStringOAuthBearerProvider(),
   AccessTokenProvider = new AuthenticationTokenProvider()
   {
       OnCreate = create,
       OnReceive = receive
   },
};

app.UseOAuthBearerAuthentication(OAuthBearerOptions);

With a custom AuthenticationTokenProvider, I can retrieve all other values from the token early in the pipeline:

public static Action<AuthenticationTokenCreateContext> create = new Action<AuthenticationTokenCreateContext>(c =>
{
    c.SetToken(c.SerializeTicket());
});

public static Action<AuthenticationTokenReceiveContext> receive = new Action<AuthenticationTokenReceiveContext>(c =>
{
    c.DeserializeTicket(c.Token);
    c.OwinContext.Environment["Properties"] = c.Ticket.Properties;
});

And now, for example in my WebSocket Hander, I can retrieve ClientId and others like this:

IOwinContext owinContext = context.GetOwinContext();
if (owinContext.Environment.ContainsKey("Properties"))
{
    AuthenticationProperties properties = owinContext.Environment["Properties"] as AuthenticationProperties;
    string clientId = properties.Dictionary["clientId"];
...
 }