DES算法的加密解密类,由于MD5很难解密,自己不方便，所以用这个了

using System;
using System.Text;
using System.IO;
using System.Security.Cryptography;


/// <summary>
/// 字符串加密、解密类，利用DES算法
/// </summary>
public class myEncrypt
{
    private static byte[] key = new byte[] { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
    private static byte[] iv = new byte[] { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };

    /// <summary>
    /// 加密
    /// </summary>
    /// <param name="notEncryptStr">待加密的明文字符串</param>
    /// <returns>加密后的字符串</returns>
    public static string EncryptString(string notEncryptStr)
    {
        //初始化加密器生成器
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        byte[] byteNotEncrypt = Encoding.UTF8.GetBytes(notEncryptStr);//将字符串转换成字节
        MemoryStream encryptMs = new MemoryStream();//创建内存数据流
        CryptoStream encryptCs = new CryptoStream(encryptMs, des.CreateEncryptor(key,iv), CryptoStreamMode.Write);//创建加密器

        //加密数据
        encryptCs.Write(byteNotEncrypt, 0, byteNotEncrypt.Length);//将字节加密并写入内存
        encryptCs.FlushFinalBlock();//将缓存中的数据写入内存
        encryptMs.Seek(0, SeekOrigin.Begin);//回到内存流开始的位置

        //将加密后的数据读取出来
        byte[] byteEncrypt = new byte[1024];
        int i = encryptMs.Read(byteEncrypt, 0, 1024);

        encryptCs.Close();

        //将加密后的字节转换为BASE64编码
        string decryptStr = Convert.ToBase64String(byteEncrypt, 0, i);
        return decryptStr;
    }

    void test()
    {
        string str1 = "Hello";
        string str2 = myEncrypt.EncryptString(str1);
    }

    /// <summary>
    /// 解密
    /// </summary>
    /// <param name="decryptStr">待解密的密文字符串</param>
    /// <returns>解密后的字符串</returns>
    public static string DecryptString(string decryptStr)
    {
        //初始化解密器生成器
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();


        byte[] byteNotDecrypt = Convert.FromBase64String(decryptStr);//将加密后的BASE64编码的字符串转换成字节
        MemoryStream decryptMs = new MemoryStream(byteNotDecrypt);//创建内存数据流
        CryptoStream decryptCs = new CryptoStream(decryptMs, des.CreateDecryptor(key, iv), CryptoStreamMode.Read);//创建解密器

        //解密数据
        byte[] byteDecrypt = new byte[1024];
        int i = decryptCs.Read(byteDecrypt, 0, 1024);
        decryptCs.Close();

        //将解密后的字节转换为BASE64编码
        string notEncryptStr = Encoding.UTF8.GetString(byteDecrypt, 0, i);
        return notEncryptStr;
    }
}