c#加密解密字符串

可以参考这里：http://msdn.microsoft.com/zh-cn/library/system.security.cryptography.descryptoserviceprovider(v=vs.80).aspx

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

namespace WanT
{
    class Encrypt
    {
        public static string Encode(string data)    //加密
        {
            byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes("56565656");
            byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes("78787878");

            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            int i = cryptoProvider.KeySize;
            MemoryStream ms = new MemoryStream();
            CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIV), CryptoStreamMode.Write);

            StreamWriter sw = new StreamWriter(cst);
            sw.Write(data);
            sw.Flush();
            cst.FlushFinalBlock();
            sw.Flush();
            return Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length);

        }

        public static string Decode(string data) //解密
        {
            byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes("56565656");
            byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes("78787878");

            byte[] byEnc;
            try
            {
                byEnc = Convert.FromBase64String(data);
            }
            catch
            {
                return null;
            }

            DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
            MemoryStream ms = new MemoryStream(byEnc);
            CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateDecryptor(byKey, byIV), CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(cst);
            return sr.ReadToEnd();
        }

    }
}