c#通过DES加密算法加密大文件的方法

本文实例讲述了c#通过des加密算法加密大文件的方法。分享给大家供大家参考。具体实现方法如下：

using system.collections;
using system.configuration;
using system.data;
using system.linq;
using system.web;
using system.web.security;
using system.web.ui;
using system.web.ui.htmlcontrols;
using system.web.ui.webcontrols;
using system.web.ui.webcontrols.webparts;
using system.xml.linq;
using system.text;
using system.io;
using system.security.cryptography;
public partial class default2 : system.web.ui.page
{
  protected void page_load(object sender, eventargs e)
  {
  }
  private static byte[] keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef };//自定义密匙
  private string filepatha;//储存文件路径
  private string filepathb;//储存文件复制后的路径
  /// <summary>
  /// 文件加密
  /// </summary>
  /// <param name="infile">文件储存路径</param>
  /// <param name="outfile">储存文件复制的路径</param>
  /// <param name="encryptkey"></param>
  /// <returns></returns>
  public bool encryptdes(string infile, string outfile, string encryptkey)
  {
   byte[] rgb = keys;
   try
   {
    byte[] rgbkeys = encoding.utf8.getbytes(encryptkey.substring(0, 8));
    filestream infs = new filestream(infile, filemode.open, fileaccess.read);//读入流
    filestream outfs = new filestream(outfile, filemode.openorcreate, fileaccess.write);// 等待写入流
    outfs.setlength(0);//帮助读写的变量
    byte[] bytein = new byte[100];//放临时读入的流
    long readlen = 0;//读入流的长度
    long totallen = infs.length;//读入流的总长度
    int everylen=0;//每次读入流的长度
    des des = new descryptoserviceprovider();//将infile加密后放到outfile
    cryptostream encstream = new cryptostream(outfs, des.createencryptor(rgb, rgbkeys), cryptostreammode.write);
    while (readlen < totallen)
    {
     everylen = infs.read(bytein, 0, 100);
     encstream.write(bytein, 0, everylen);
     readlen = readlen + everylen;
    }
    encstream.close();
    infs.close();
    outfs.close();
    return true;//加密成功
   }
   catch (exception ex)
   {
    response.write(ex.message.tostring());
    return false;//加密失败
   }
  }

  public bool decryptdes(string infile, string outfile, string encryptkey)
  {
   byte[] rgb = keys;
   try
   {
    byte[] rgbkeys = encoding.utf8.getbytes(encryptkey.substring(0, 8));
    filestream infs = new filestream(infile, filemode.open, fileaccess.read);//读入流
    filestream outfs = new filestream(outfile, filemode.openorcreate, fileaccess.write);// 等待写入流
    outfs.setlength(0);//帮助读写的变量
    byte[] bytein = new byte[100];//放临时读入的流
    long readlen = 0;//读入流的长度
    long totallen = infs.length;//读入流的总长度
    int everylen=0;//每次读入流的长度
    des des = new descryptoserviceprovider();//将infile加密后放到outfile
    cryptostream encstream = new cryptostream(outfs, des.createdecryptor(rgb, rgbkeys), cryptostreammode.write);
    while (readlen < totallen)
    {
     everylen = infs.read(bytein, 0, 100);
     encstream.write(bytein, 0, everylen);
     readlen = readlen + everylen;
    }
    encstream.close();
    infs.close();
    outfs.close();
    return true;//加密成功
   }
   catch (exception ex)
   {
    response.write(ex.message.tostring());
    return false;//加密失败
   }
  }
  /// <summary>
  /// 拷贝文件
  /// </summary>
  public void copyfile()
  {
   filepatha = this.fei.postedfile.filename;//获取文件全部路径
   string filename = this.fei.filename;
   string path = system.io.path.getdirectoryname(filepatha);
   filepathb = path + "\\1" + filename;//重新设置文件名
   file.copy(filepatha, filepathb);
  }
  protected void btnok_click(object sender, eventargs e)
  {
   copyfile();
   if (encryptdes(filepathb, filepatha, "mingrisoft"))
   {
    registerstartupscript("false", "<script>alert('加密成功!\\n');</script>");
   }
   else
   {
    registerstartupscript("false", "<script>alert('失败成功!\\n');</script>");
   }
   file.delete(filepathb);
  }
  protected void btncancel_click(object sender, eventargs e)
  {
   copyfile();
   if (decryptdes(filepathb, filepatha, "mingrisoft"))
   {
    registerstartupscript("false", "<script>alert('加密成功!\\n');</script>");
   }
   else
   {
    registerstartupscript("false", "<script>alert('失败成功!\\n');</script>");
   }
   file.delete(filepathb);
  }
}

希望本文所述对大家的c#程序设计有所帮助。