UDP协议实现对等通讯Java+RSA加密解密传送信息实现
摘要
本文介绍了一个基于UDP协议的对等通讯Java实现方案，采用RSA加密算法确保信息安全。 系统包含客户端和服务器端（两者代码相同），通过DatagramSocket实现消息收发。 客户端使用服务器公钥加密发送消息，接收时用自身私钥解密。
文章详细展示了包括界面设计、密钥初始化、消息加密/解密和网络通信在内的完整代码实现， 实现了本地主机（127.0.0.1）在55512和55513端口间的安全通讯。 该方案采用固定RSA密钥参数，通过时间戳记录通讯过程，具有完整的错误处理机制。
思路流程
执行效果
代码
下面贴出客户端代码（RSA算法部分参照开头的说明链接，因为是对等通讯，所以服务端代码和客户端是一样的，只是他们的监听和发送端口互换而已）：
import java.awt.EventQueue;
import java.awt.Rectangle;
import java.awt.TextArea;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
import java.awt.event.ActionEvent;
import java.awt.event.WindowEvent;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import myrsa2.RSAUtils;
public class ClientWindow1 extends JFrame implements Runnable
{
private static final long serialVersionUID = -9061845795224200533L;
private JPanel contentPane;
JLabel jLabel1 = new JLabel();
TextArea jTextArea1 = new TextArea("你好! ", 100, 250,TextArea.SCROLLBARS_VERTICAL_ONLY);
JLabel jLabel2 = new JLabel();
JTextField jTextField1 = new JTextField();
Thread c;
private DatagramSocket sendSocket, receiveSocket;
private DatagramPacket sendPacket, receivePacket;
//server端公钥参数
private String public_exponent="65537";
private String modulus="104344065049535235337602750745972062206029307981021347712560211453856339371441553987973583092897777954138410872748183586468653712704255491417965770505559379560464351555212396558781035059397673682011104226754831711072822991514780158821061675743098642785196847109412740308768227675829387795015925250708654667999";
private RSAPublicKey pubKey;
//client 端公钥密钥参数
private String client_modulus="113073745494321136725643384276722554235918070888758423613996572688337880324241477133718433831999005142699224319183845232695295297468715990337671678419444783042160223540025404015195691927944232410884578134672967651594589403061833363946041818438441160271287476138927799777730705047831779398357394582752490728477";
private String client_public_exponent="65537";
private String client_private_exponent="96655390029103626966557334491451763291733925099701476254325068260270936930960095678899558748530086319165559082426693223382564625471030692505099487262702213820107182483208312048057602807578526587131082022149038938961334471000154642010315296540992797729318728885945908324955019647195175495375437240594636763713";
private RSAPublicKey client_pubKey;
private RSAPrivateKey client_priKey;
/**
* Launch the application.
*/
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
try
{
ClientWindow1 frame = new ClientWindow1();
frame.setVisible(true);
} catch (Exception e)
{
e.printStackTrace();
}
}
});
}
/*initial the pubkey and prikey
*/
public void InitKey()
{
//使用模和指数生成公钥和私钥
pubKey = RSAUtils.getPublicKey(modulus, public_exponent);
jTextArea1.append("\nserver publicKey:" + pubKey);
client_pubKey = RSAUtils.getPublicKey(client_modulus, client_public_exponent);
jTextArea1.append("\nclient publicKey:" + client_pubKey);
client_priKey= RSAUtils.getPrivateKey(client_modulus, client_private_exponent);
}
/**
* Create the frame.
*/
public ClientWindow1()
{
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 430, 500);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
//this.setSize(new Dimension(400, 400));
this.setTitle("UDPClient");
jLabel1.setText("通信记录:");
jLabel1.setBounds(new Rectangle(10, 3, 70, 30));
contentPane.setLayout(null);
jTextArea1.setBounds(new Rectangle(15, 30, 400, 350));
jTextArea1.setEditable(false);
InitKey();
jLabel2.setText("输入通信内容:");
jLabel2.setBounds(new Rectangle(17, 385, 92, 37)); // 创建输入内容区域
jTextField1.setText("");
jTextField1.setBounds(new Rectangle(130, 385, 244, 31));
jTextField1.setEditable(true);
//监听输入框的回车事件
jTextField1.addActionListener(new java.awt.event.ActionListener()
{
public void actionPerformed(ActionEvent e)
{
//执行，发送输入框信息
jTextField1_actionPerformed(e);
}
});
contentPane.add(jLabel1, null);
contentPane.add(jTextArea1, null);
contentPane.add(jTextField1, null);
contentPane.add(jLabel2, null);
try
{
sendSocket = new DatagramSocket();
receiveSocket = new DatagramSocket(55512);
} catch (SocketException e)
{
jTextArea1.append("不能打开数据报Socket,或者数据报Socket无法与指定端口连接！");
}
// 创建一个线程,监听本机55512端口，执行run();方法
c = new Thread(this);
c.start();
}
protected void processWindowEvent(WindowEvent e) {
super.processWindowEvent(e);
if (e.getID() == WindowEvent.WINDOW_CLOSING) {
System.exit(0);
}
}
void jTextField1_actionPerformed(ActionEvent e)
{
try
{
Date date=new Date();
DateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String time=format.format(date);
jTextArea1.append("\n\n客户端:"+time);
String string1 = jTextField1.getText().trim();
jTextArea1.append("\n加密前明文:"+string1);
//加密后的密文
string1 = RSAUtils.encryptByPublicKey(string1, pubKey);
jTextArea1.append("\n加密后密文:"+string1);
//将信息发送到IP： 127.0.0.1 的55513端口
sendPacket = new DatagramPacket(string1.getBytes(),
string1.getBytes().length,
java.net.InetAddress.getByName("127.0.0.1"), 55513);
sendSocket.send(sendPacket);
} catch (IOException ioe)
{
jTextArea1.append("\n网络通信出现错误,问题在于" + e.toString());
} catch (Exception e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
@Override
public void run()
{
// TODO Auto-generated method stub
while (true)
{
try
{
byte buf[] = new byte[256];//接受的最大长度，超出的长度被丢弃
receivePacket = new DatagramPacket(buf, buf.length);
receiveSocket.receive(receivePacket);
Date date=new Date();
DateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String time=format.format(date);
jTextArea1.append("\n\n服务器："+time);
byte[] data = receivePacket.getData();
String receiveString = new String(data);
jTextArea1.append("\n解密前密文："+receiveString);
receiveString = RSAUtils.decryptByPrivateKey(receiveString, client_priKey);
jTextArea1.append("\n解密后密文："+receiveString);
} catch (IOException e)
{
jTextArea1.append("\n网络通信出现错误,问题在于" + e.toString());
} catch (Exception e)
{
// TODO Auto-generated catch block
jTextArea1.append("\nRSAUtils.decryptByPrivateKey error!!!:" + e.toString());
}
}
}
}