Two factor auth with IdentityServer3 - remember browser
<p>I'm implementing 2fa with IdentityServer3 + Asp.Net Identity (2.2.1). I'm stuck on the 2fa implementation. I've looked at the "AspNetIdentity_2fa" sample, which helped a lot.</p>

<p>I have everything wired up, except for the cookie that indicates the browser has been successfully authenticated. I can set the cookie during the code confirmation, but I cannot get to the cookie in the PostAuthenticateLocalAsync() call to see whether or not to take the 2fa path.</p>

<pre><code>        protected override Task&lt;AuthenticateResult&gt; PostAuthenticateLocalAsync(User user, SignInMessage message)
    {
        if (user.TwoFactorEnabled) // &amp;&amp; !TwoFactorCookieSet...
        {
            return Task.FromResult(new AuthenticateResult("/auth/sendcode", user.Id, user.DisplayName));
        }

        return base.PostAuthenticateLocalAsync(user, message);
    }
</code></pre>

<p>I believe I'm taking the correct approach in using the partial logins, but how would I detect that the current browser has already been approved?</p>

<p>More detail: the /auth/sendcode is the standard Asp.Net Identity pages/flow for 2fa, combined with the partial login logic from the sample.</p>