C#—非对称加密：加密文件
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说明：
1.你要注意的是读取文件的两种不同方式；
2.从已经保存的钥匙文件中读取其内容；
3.这个程序做的很粗糙（要准备考外语六级，要准备期末考试，实在很忙啊！），希望诸位能够完善，然后也发表出来，在下表示感谢；
4.参考书目： 《C#数据安全手册》;
5.有做这方面程序的朋友，愿意相交。
代码部分：

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

namespace 非对称加密
{
/// <summary>
/// Form1 的摘要说明。
/// </summary>
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.TabControl tabControl1;
private System.Windows.Forms.TabPage tabPage1;
private System.Windows.Forms.TabPage tabPage2;
private System.Windows.Forms.TabPage tabPage3;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.Button button3;
private System.Windows.Forms.SaveFileDialog save;
private System.Windows.Forms.Label label1;
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.Button button4;
private System.Windows.Forms.Button button5;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.RichTextBox richtext2;
private System.Windows.Forms.OpenFileDialog open;
private System.Windows.Forms.Label label3;
private System.Windows.Forms.RichTextBox richtext3;
private System.Windows.Forms.RichTextBox richtext;
private System.Windows.Forms.Button button6;
private System.Windows.Forms.Button button7;
private System.Windows.Forms.Button button8;
private System.Windows.Forms.TextBox textBox2;
private System.Windows.Forms.Label label4;
private System.Windows.Forms.Button button9;
private System.Windows.Forms.TextBox textBox3;
private System.Windows.Forms.Label label5;
private System.Windows.Forms.Button button10;
private System.Windows.Forms.Label label6;
private System.Windows.Forms.Button button11;
private System.Windows.Forms.Button button12;
private System.Windows.Forms.RichTextBox richtext4;
private System.Windows.Forms.Button button13;
private System.Windows.Forms.Button button14;
private System.Windows.Forms.Button button15;
private System.Windows.Forms.TabPage tabPage4;
private System.Windows.Forms.TextBox textBox4;
private System.Windows.Forms.Button button16;
private System.Windows.Forms.TextBox textBox5;
private System.Windows.Forms.Button button17;
private System.Windows.Forms.Button button18;
private System.Windows.Forms.Button button19;
private System.Windows.Forms.Button button20;
private System.Windows.Forms.Button button21;
private System.Windows.Forms.RichTextBox richtext5;
/// <summary>
/// 必需的设计器变量。
private static RSACryptoServiceProvider crypt;
private static string privatekey;
private static string publickey;
private static byte [] bytes;
private static string publicinfo;
private static string privateinfo;
private static string readpublickey;
private static string readprivatekey;
//文件打开和是否读取钥匙的标记
private bool openla = false;
private bool savela = false;
private bool readpubkey=false;
private bool readprikey=false;
private Thread th;
/// </summary>
private System.ComponentModel.Container components = null;
<