用C＃实现Des加密和解密

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Security.Cryptography;
using System.IO;

namespace SoftEncrypt
...{
    public partial class Form1 : Form
    ...{
        const string KEY_64 = "12345678";
        const string IV_64 = "98765432"; //注意了，是8个字符，64位 

        public Form1()
        ...{
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        ...{
            textBox2.Text = Encode(textBox1.Text.Trim());

        }


        public static string Encode(string data)
        ...{
            byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);
            byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);

            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)
        ...{
            byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);
            byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);

            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();
        }

        private void button2_Click(object sender, EventArgs e)
        ...{
            textBox1.Text = Decode(textBox2.Text.Trim());
        } 

    }
}