MVC external authentication with the [Authorize] attribute

Question

A site authorizes through a separate system. Once the user is authorized, I want to store some additional information with their Auth cookie. I am able to do this using the code below.

var settings = new JsonSerializerSettings { ContractResolver = new CamelCasePropertyNamesContractResolver() };
var serialized = JsonConvert.SerializeObject(accountNumber, Formatting.None, settings);
var authTicket = new FormsAuthenticationTicket(1, "MyAuthTicket", DateTime.Now, DateTime.Now.AddMinutes(15),
    false, serialized);
var encTicket = FormsAuthentication.Encrypt(authTicket);
var faCookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket)
{
    HttpOnly = true,
};
Response.Cookies.Add(faCookie);

However, when I try to hit a WebAPI method marked with [Authorize], I get a 401 Unauthorized error. What am I missing?

Answer 1

The following needs added to web.config:

<system.web>
    <authentication mode="Forms">
    </authentication>
    <!-- other stuff -->
<system.web>