Add Claims during the OWIN pipeline with Windows Authentication - asp.net-mvc-5

Question

I'm trying to explore how it's possible to add additional claims to a User during the OWIN pipeline.
I know that I can do this at the login stage or at some other points, possibly in the Application_PostAuthenticate section in the Global.asax since I don't have a Login section (it's a Windows Authentication app), but I was wondering if it's possible or even better to do it in the OWIN pipeline.
My idea comes from the fact that OWIN too has a PostAuthenticate stage in the pipeline. So I tried this:
app.Use((context, next) =>
{
var user = context.Authentication.User.Identity as ClaimsIdentity;
if (user != null)
{
user.AddClaim(new Claim(ClaimTypes.Role, "Admin"));
user.AddClaim(new Claim(ClaimTypes.GivenName, "Mr. Tallmaris"));
}
return next.Invoke();
});
With a break point I can see that the user is the correct one and that the claims are added, but in my View I have something like this:
<ul>
#foreach (var claim in ClaimsPrincipal.Current.Claims)
{
<li>#claim.Type - #claim.Value</li>
}
</ul>
But my newly added claims are not showing up. Any ideas?
I know that "some" claims need to be added at Application level anyway (roles coming from DB and other things) but I would like to explore adding certain claims straight from the OWIN pipeline.

Answer 1

I used this principle in my asp.net application for converting groupsid claims to role claims.
app.Use((context, func) => {
var claimsIdentity = context.Authentication.User.Identity as ClaimsIdentity;
if (claimsIdentity != null) {
var claimsToAdd = new List<Claim>();
//check if we have any groupsid claims, add these as role claims
foreach (var claim in claimsIdentity.Claims) {
if (claim.Type == ClaimTypes.GroupSid) {
claimsToAdd.Add(new Claim(ClaimTypes.Role,
new SecurityIdentifier(claim.Value)
.Translate(typeof(NTAccount)).ToString()));
}
}
if (claimsToAdd.Count > 0) {
claimsIdentity.AddClaims(claimsToAdd);
}
}
return func.Invoke();
});
This worked for me using Microsoft.Owin v3.0.0.0