AuthCacheCustomAuthenticationHttpModule.cs

using System;
using System.IdentityModel.Services;
using System.Security.Claims;
using System.Threading;
using System.Web;

namespace CustomAuth
{
    public class CacheCustomAuthenticationHttpModule : IHttpModule
    {
        public void Dispose()
        { 
            // nothing to dispose...
        }

        public void Init(HttpApplication context)
        {
            // wire up our custom authentication after default Windows Authentication
            context.PostAuthenticateRequest += Context_PostAuthenticateRequest;
        }

        void Context_PostAuthenticateRequest(object sender, EventArgs e)
        {
            var context = ((HttpApplication)sender).Context;

            // no need to call transformation if session already exists
            if (FederatedAuthentication.SessionAuthenticationModule != null &&
                FederatedAuthentication.SessionAuthenticationModule.ContainsSessionTokenCookie(context.Request.Cookies))
            {
                return;
            }

            // find our CustomAuthenticationManager instance
            var transformer = FederatedAuthentication.FederationConfiguration.IdentityConfiguration.ClaimsAuthenticationManager;
            if (transformer != null)
            {
                // Invoke authentication which will process/transform claims
                var transformedPrincipal = transformer.Authenticate(context.Request.RawUrl, context.User as ClaimsPrincipal);

                // set context and thread user
                context.User = transformedPrincipal;
                Thread.CurrentPrincipal = transformedPrincipal;
            }
        }
    }
}