private void ThemDangKy()
 {
     using (var md5Hash = MD5.Create())
     {
         var kh = new Kh
         {
             Email   = Request.Form["email"].Replace(",", ""),
             MatKhau = SecurityHelper.GetMd5Hash(md5Hash, Request.Form["password"].Replace(",", "")),
             TenKh   = Request.Form["f_Name"].Replace(",", "")
         };
         KhBus.Insert(kh);
         Response.Redirect("/GioHang", false);
     }
 }
        public static string Login(FilterClass fc)
        {
            var    email = fc.Email;
            string password;

            using (var md5Hash = MD5.Create())
            {
                password = SecurityHelper.GetMd5Hash(md5Hash, fc.Password);
            }

            var kh = KhBus.GetAll().FirstOrDefault(m => m.Email == email && m.MatKhau == password);

            if (kh != null)
            {
                HttpContext.Current.Session["uid"]  = kh.MaKh;
                HttpContext.Current.Session["name"] = kh.TenKh;
                return("Thành công");
            }

            return("<span style='color:red;'>Đăng ký nếu chưa có tài khoản!</span>");
        }