我正在尝试制作一个使用AES加密来发送数据的聊天程序（基于this），但我遇到了一些问题。我已经加密了这些消息（我认为...... [这只是我的第二个程序所以我对Java很新]）但是当我尝试解密消息时，程序找不到先前创建的符号“cipher” 。下面是错误的地方：
public void run() throws IOException {
// Make connection and initialize streams
String serverAddress = getServerAddress();
Socket socket = new Socket(serverAddress, 9001);
in = new BufferedReader(new InputStreamReader(
socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(), true);
// Process all messages from server, according to the protocol.
while (true) {
String line = in.readLine();
if (line.startsWith("SUBMITNAME")) {
out.println(getName());
} else if (line.startsWith("NAMEACCEPTED")) {
textField.setEditable(true);
} else if (line.startsWith("MESSAGE")) {
//DECRYPTION
messageArea.append(line.substring(8) + "\n");
cipher.init(Cipher.DECRYPT_MODE, key);
line = new String(cipher.doFinal(line));
System.out.println(line);
}
}
}
创建密码的地方：
public void actionPerformed(ActionEvent e) {
try {
String input = (textField.getText());
//ENCRYPTION
MessageDigest md5 = MessageDigest.getInstance("MD5");
md5.update("So What's Up Doc?".getBytes());
SecretKeySpec key = new SecretKeySpec(md5.digest(), "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, key);
byte encryptedMessage[] = cipher.doFinal(input.getBytes());
//Sends the encrypted version of message
System.out.println(encryptedMessage);
out.println(encryptedMessage);
//Clears the input box
textField.setText("");
} catch ( NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException ex) {
Logger.getLogger(ChatClient.class.getName()).log(Level.SEVERE, null, ex);
}
}
完整的代码在这里：
package Chat.Application;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import java.security.GeneralSecurityException;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;
import org.omg.PortableInterceptor.SYSTEM_EXCEPTION;
/**
* A simple Swing-based client for the chat server. Graphically
* it is a frame with a text field for entering messages and a
* textarea to see the whole dialog.
*
* The client follows the Chat Protocol which is as follows.
* When the server sends "SUBMITNAME" the client replies with the
* desired screen name. The server will keep sending "SUBMITNAME"
* requests as long as the client submits screen names that are
* already in use. When the server sends a line beginning
* with "NAMEACCEPTED" the client is now allowed to start
* sending the server arbitrary strings to be broadcast to all
* chatters connected to the server. When the server sends a
* line beginning with "MESSAGE " then all characters following
* this string should be displayed in its message area.
*/
public class ChatClient {
BufferedReader in;
PrintWriter out;
JFrame frame = new JFrame("ELECTRON Chatroom");
JTextField textField = new JTextField(40);
JTextArea messageArea = new JTextArea(8, 40);
/**
* Constructs the client by laying out the GUI and registering a
* listener with the textfield so that pressing Return in the
* listener sends the textfield contents to the server. Note
* however that the textfield is initially NOT editable, and
* only becomes editable AFTER the client receives the NAMEACCEPTED
* message from the server.
*/
public ChatClient() {
// Layout GUI
textField.setEditable(false);
messageArea.setEditable(false);
messageArea.setWrapStyleWord(true);
messageArea.setLineWrap(true);
frame.getContentPane().add(textField, "North");
frame.getContentPane().add(new JScrollPane(messageArea), "Center");
frame.pack();
// Add Listeners
textField.addActionListener(new ActionListener() {
/**
* Responds to pressing the enter key in the textfield by sending
* the contents of the text field to the server. Then clear
* the text area in preparation for the next message.
*/
@Override
public void actionPerformed(ActionEvent e) {
try {
String input = (textField.getText());
//ENCRYPTION
MessageDigest md5 = MessageDigest.getInstance("MD5");
md5.update("So What's Up Doc?".getBytes());
SecretKeySpec key = new SecretKeySpec(md5.digest(), "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, key);
byte encryptedMessage[] = cipher.doFinal(input.getBytes());
//Sends the encrypted version of message
System.out.println(encryptedMessage);
out.println(encryptedMessage);
//Clears the input box
textField.setText("");
} catch ( NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException ex) {
Logger.getLogger(ChatClient.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
}
/**
* Prompt for and return the address of the server.
*/
private String getServerAddress() {
return JOptionPane.showInputDialog(
frame,
"Enter IP Address of the Server:",
"ELECTRON Chatroom",
JOptionPane.QUESTION_MESSAGE);
}
/**
* Prompt for and return the desired screen name.
*/
private String getName() {
return JOptionPane.showInputDialog(
frame,
"Choose a screen name:",
"Screen name selection",
JOptionPane.PLAIN_MESSAGE);
}
/**
* Connects to the server then enters the processing loop.
*/
public void run() throws IOException {
// Make connection and initialize streams
String serverAddress = getServerAddress();
Socket socket = new Socket(serverAddress, 9001);
in = new BufferedReader(new InputStreamReader(
socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(), true);
// Process all messages from server, according to the protocol.
while (true) {
String line = in.readLine();
if (line.startsWith("SUBMITNAME")) {
out.println(getName());
} else if (line.startsWith("NAMEACCEPTED")) {
textField.setEditable(true);
} else if (line.startsWith("MESSAGE")) {
//DECRYPTION
messageArea.append(line.substring(8) + "\n");
cipher.init(Cipher.DECRYPT_MODE, key);
line = new String(cipher.doFinal(line));
System.out.println(line);
}
}
}
/**
* Runs the client as an application with a closeable frame.
*/
public static void main(String[] args) throws Exception {
ChatClient client = new ChatClient();
client.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
client.frame.setVisible(true);
client.run();
}
}
AES加密的代码来自here
我确信这是一个简单的解决方案，但是AES加密部分与它有任何关系，但也可以添加它。感谢你的帮助！ - 银
编辑 - 错误：
no suitable method found for doFinal(String)
method Cipher.doFinal(ByteBuffer,ByteBuffer) is not applicable
(actual and formal argument lists differ in length)
method Cipher.doFinal(byte[],int,int,byte[],int) is not applicable
(actual and formal argument lists differ in length)
method Cipher.doFinal(byte[],int,int,byte[]) is not applicable
(actual and formal argument lists differ in length)
method Cipher.doFinal(byte[],int,int) is not applicable
(actual and formal argument lists differ in length)
method Cipher.doFinal(byte[]) is not applicable
(actual argument String cannot be converted to byte[] by method invocation conversion)
method Cipher.doFinal(byte[],int) is not applicable
(actual and formal argument lists differ in length)
method Cipher.doFinal() is not applicable
(actual and formal argument lists differ in length)
答案 0 :(得分：1)
使cicher成为全局变量。在类的顶层声明它：
Cipher cipher;
变化：
Cipher cipher = Cipher.getInstance("AES");
为：
cipher = Cipher.getInstance("AES");
在此处添加null支票：
if (cipher != null) {
cipher.init(Cipher.DECRYPT_MODE, key);
line = new String(cipher.doFinal(line));
System.out.println(line);
}
基本上，变量cipher在您尝试使用它的地方是未知的。在顶层声明它将使整个班级都可见。如果在此＆lt; - 订单中调用null和actionPerformed(ActionEvent)，则不需要run()检查。