加密  Cookies
Response.Cookies["askCRM"]["USERID"] = Tools.Encrypt(strUserName.Trim(), Tools.myKey);
解密
string strUid = Request.Cookies["askCRM"]["USERID"];
strUid = Tools.Decrypt(strUid, Tools.myKey);

加密解密 掉用的方法
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Security.Cryptography;
using System.IO;
using System.Text;

/// <summary>
/// Tools 的摘要说明


/// </summary>
public class Tools
{
  

    /// <summary>
    /// 当前程序加密所使用的密钥

    /// </summary>
    public static readonly string myKey = "q0m3sd8l";

    #region 加密方法
    /// <summary>
    /// 加密方法
    /// </summary>
    /// <param name="pToEncrypt">需要加密字符串</param>
    /// <param name="sKey">密钥</param>
    /// <returns>加密后的字符串</returns>
    public static string Encrypt(string pToEncrypt, string sKey)
    {
        try
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            //把字符串放到byte数组中


            //原来使用的UTF8编码,我改成Unicode编码了,不行
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);

            //建立加密对象的密钥和偏移量


            //使得输入密码必须输入英文文本
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);

            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();
        }
        catch (Exception ex)
        {
            JS.Alert("写入配置信息失败,详细信息:" + ex.Message.Replace("\r\n", "").Replace("'", ""));
        }

        return "";
    }
    #endregion

    #region 解密方法
    /// <summary>
    /// 解密方法
    /// </summary>
    /// <param name="pToDecrypt">需要解密的字符串</param>
    /// <param name="sKey">密匙</param>
    /// <returns>解密后的字符串</returns>
    public static string Decrypt(string pToDecrypt, string sKey)
    {
        try
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < pToDecrypt.Length / 2; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }

            //建立加密对象的密钥和偏移量,此值重要,不能修改
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            //建立StringBuild对象,CreateDecrypt使用的是流对象,必须把解密后的文本变成流对象
            StringBuilder ret = new StringBuilder();
            return System.Text.Encoding.Default.GetString(ms.ToArray());
        }
        catch (Exception ex)
        {
            JS.Alert("读取配置信息失败,详细信息:" + ex.Message.Replace("\r\n", "").Replace("'", ""));
        }
        return "";
    }
    #endregion
}