用C#写DES加密算法

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

namespace desfile
{
    public partial class Form1 : Form
    {
        string fileName;
        string desFileName;

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog openFileDialog = new OpenFileDialog();
            openFileDialog.InitialDirectory = "c://";
            openFileDialog.Filter = "文本文件|*.*|C#文件|*.cs|所有文件|*.*";
            openFileDialog.RestoreDirectory = true;
            openFileDialog.FilterIndex = 1;
            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                fileName = openFileDialog.FileName;
                textBox1.Text = fileName;
            }  
        }

        private void button2_Click(object sender, EventArgs e)
        {
            desFileName = fileName + "E";
            FileStream fin = new FileStream(fileName, FileMode.Open, FileAccess.Read);
            FileStream fout = new FileStream(desFileName, FileMode.OpenOrCreate, FileAccess.Write);
            fout.SetLength(0);
            byte[] bin = new byte[1000];
            long rdlen = 0;
            //This is the total number of bytes written.

            long totlen = fin.Length;
            int len;
            DES des = new DESCryptoServiceProvider();
            byte[] desKey = ASCIIEncoding.ASCII.GetBytes("luckyprg");
            //the keys length must be morethan 8
            byte[] desIV = ASCIIEncoding.ASCII.GetBytes("luckyprg");

            CryptoStream encStream = new CryptoStream(fout, des.CreateEncryptor(desKey, desIV), CryptoStreamMode.Write);
            while (rdlen < totlen)
            {
                len = fin.Read(bin, 0, 1000);
                encStream.Write(bin, 0, len);
                rdlen = rdlen + len;
            }
            encStream.Close();
            fout.Close();
            fin.Close();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            desFileName = fileName + "D";
            FileStream fin = new FileStream(fileName, FileMode.Open, FileAccess.Read);
            FileStream fout = new FileStream(desFileName, FileMode.OpenOrCreate, FileAccess.Write);
            fout.SetLength(0);
            byte[] bin = new byte[1000];
            long rdlen = 0;
            //This is the total number of bytes written.

            long totlen = fin.Length;
            int len;
            DES des = new DESCryptoServiceProvider();
            byte[] desKey = ASCIIEncoding.ASCII.GetBytes("luckyprg");
            //the keys length must be morethan 8
            byte[] desIV = ASCIIEncoding.ASCII.GetBytes("luckyprg");

            CryptoStream encStream = new CryptoStream(fout, des.CreateDecryptor(desKey, desIV), CryptoStreamMode.Write);
            while (rdlen < totlen)
            {
                len = fin.Read(bin, 0, 1000);
                encStream.Write(bin, 0, len);
                rdlen = rdlen + len;
            }
            encStream.Close();
            fout.Close();
            fin.Close();
        }
    }
}