asp.net读取asp的cookies 及乱码问题

System.Text.Encoding   enc   =   System.Text.Encoding.GetEncoding("gb2312");     
  string   cookie   =   Request.Cookies["YourCookieName"].Value;     
  string   cookieValue   =   HttpUtility.UrlDecode(   cookie,enc);

 System.Text.Encoding enc = System.Text.Encoding.GetEncoding("gb2312");
        for (int i = 0; i < HttpContext.Current.Request.Cookies.Count; i++)
        {
            if (HttpContext.Current.Request.Cookies.Keys[i] == null)
                return;
            
                if (HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies.Keys[i]).ToString() == "admin_session_offices")
                  admin_session_offices = HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies[i].Value.ToString(), enc);

              if (HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies.Keys[i]).ToString() == "admin_session_caozuos")
                  admin_session_caozuos = HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies[i].Value.ToString(), enc);

              if (HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies.Keys[i]).ToString() == "admin_session_cishu")
                  admin_session_cishu = HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies[i].Value.ToString(), enc);                    
        
            ////输出测试
            //Response.Write(HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies.Keys[i], enc) + ":" + HttpUtility.UrlDecode(HttpContext.Current.Request.Cookies[i].Value.ToString(), enc) + "<br>");
        } 

//************************** 关于键名乱码的解决方案

<div style="padding-top: 4px; text-align: right; font-weight: normal">
            <%=request.Cookies("admin_session_offices")%>
            &nbsp;&nbsp;<%=request.Cookies("admin_session_caozuos")%>&nbsp;&nbsp;<br>
            累计登陆<%=request.Cookies("admin_session_cishu")%>次&nbsp;&nbsp;</div>

---------------------------------------------以上是asp的读取。。
aspx：

HttpContext.Current.Request.Cookies["admin_session_caozuos"].Value 报错，而
HttpContext.Current.Request.Cookies["admin%5Fsession%5Fcaozuos"].Value 这样的取值却有效果，
如何统一把cookie里的键及值重新解码??