using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Text;
using System.IO;
using System.Security.Cryptography;

/// <summary>
///CookiesHelper 的摘要说明
/// </summary>
// 这个类是实现了DES的加密和解密
public class CookieHelper
{
    //URL传输参数加密Key这个key可以自己设置支持8位这个东西很重要的,密钥
    static string _QueryStringKey = "e2345678";

    /// <summary>
    /// 加密算法
    /// </summary>
    public static string EncryptQueryString(string QueryString)
    {
        return Encrypt(QueryString, _QueryStringKey);
    }


    /// <summary>
    /// 解密算法
    /// </summary>
    public static string DecryptQueryString(string QueryString)
    {
        return Decrypt(QueryString, _QueryStringKey);
    }


    public static string Encrypt(string originalString, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();

            // 把字符串放到byte数组中
            byte[] inputByteArray = Encoding.Default.GetBytes(originalString);

            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey); //建立加密对象的密钥和偏移量
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);  //原文使用ASCIIEncoding.ASCII方法的

                                                            //GetBytes方法
            MemoryStream ms = new MemoryStream();         //使得输入密码必须输入英文文本
            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();
        }

    public static string Decrypt(string originalString, string sKey)
    {
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        byte[] inputByteArray = new byte[originalString.Length / 2];
        for (int x = 0; x < originalString.Length / 2; x++)
        {
            int i = (Convert.ToInt32(originalString.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());
    }

}