MVC 4 Web Api Authentication - asp.net

Question

I've spent days trying to find examples, but none appear to answer what it is I am looking for. Most other examples are for later versions of Web API.
I am currently consuming a REST web service, that uses basic authentication. I want to emulate this in mine. The path is /api/authenticate
I pass a header of Authorization Basic [base 64 username / password]. The response I am currently seeing is a response code of 200, and a json response that has the session token (among other things).
For future calls, I then pass the session token in an X header back to the server, and that then passes all of my calls.
I'm trying to write a web api that works in a very similar way.
I've done very little with web api, so am a bit lost. Here is what I have so far...
public string[] Post([FromBody]string value)
{
if (Request.Headers.Authorization == null)
{
System.Web.HttpContext.Current.Response.AddHeader("WWW-Authenticate", "Basic");
System.Web.HttpContext.Current.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
}
else
{
// Check for valid users
string authToken = Request.Headers.Authorization.Parameter;
string decodedToken = Encoding.UTF8.GetString(Convert.FromBase64String(authToken));
string username = decodedToken.Substring(0, decodedToken.IndexOf(":"));
string password = decodedToken.Substring(decodedToken.IndexOf(":") + 1);
if (username == "MyApiUserName" && password == "MyApiPassword")
{
// The line below doesn't work yet.
//WebSecurity.Login(model.Username, model.Password, persistCookie: true);
System.Web.HttpContext.Current.Response.AddHeader("Test", "Something");
System.Web.HttpContext.Current.Response.StatusCode = (int)HttpStatusCode.OK;
Pair[0] = username;
Pair[1] = password;
return Pair;
}
else
{
System.Web.HttpContext.Current.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
}
}
return null;
}
What I need is to respond once authenticated with a session token in the json response and I also need to know how to use that session token in my other API calls.

Answer 1

Asp.net Api has its own authentication methods, so you don't need to implement them by yourself. this is why all examples are for latest versions of Web API.
if you want return json responce try to use JsonResult instead of string[ ]
see this https://msdn.microsoft.com/en-us/library/system.web.mvc.jsonresult(v=vs.118).aspx