my last dev

/*
* This is my last dev, which is a module to auth user by base windows auth using 401 request
*/

   public class Module : IHttpModule
    {
        private static readonly List<string> AuthList = new List<string>();
        #region IHttpModule Implements
        public void Init(HttpApplication context)
        {
            context.BeginRequest += AddRequestHeaders;
            context.BeginRequest += CheckAuthentication;
        }

        public void Dispose()
        {
            //empty
        }
        #endregion

        #region Misc Functions

        private void AddRequestHeaders(object sender, EventArgs e)
        {
            var app = (HttpApplication) sender;
            app.Context.Response.AddHeader("X-MyModuleAuth", "true");
        }

        private void CheckAuthentication(object sender, EventArgs e)
        {
            var app = (HttpApplication) sender;

            var authHeader = app.Context.Request.Headers["Authorization"];
            if (AuthList.Contains(authHeader)) return;
            if (authHeader != null && authHeader.StartsWith("Basic"))
            {
                var encodeId = authHeader.Substring("Basic ".Length).Trim();
                var encoding = Encoding.GetEncoding("iso-8859-1");
                var strId = encoding.GetString(Convert.FromBase64String((encodeId)));

                var sep = strId.IndexOf(':');
                var user = strId.Substring(0, sep);
                var pass = strId.Substring(sep + 1);

                try
                {
                    var usr = FTELNASAuthentication.ValidateUser(user, pass);
                    if (usr != null)
                    {
                        AuthList.Add(authHeader);
                        return;
                    }

                }
                catch (Exception ex)
                {
                    //empty for the moment.
                }

            }
            app.Context.Response.Headers["WWW-Authenticate"] = "Basic";
            app.Context.Response.StatusCode = 401;
            app.CompleteRequest();
        }
        #endregion

    }