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POCannot send AES encrypted messages of over 47 characters
 

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  1. POCannot send AES encrypted messages of over 47 characters
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    <p>Ello mates! I am creating an AES encrypted chat program but have ran into an issue; Whenever a message is over 47 characters, it displays "javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher". I understand the error message but I can't seem to figure out how to fix it. Here is my FULL code: ChatClient.java package Chat.Application;</p> <pre><code>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 javax.swing.text.*; import java.security.*; import java.util.logging.Level; import java.util.logging.Logger; import javax.crypto.*; import javax.crypto.spec.SecretKeySpec; import sun.misc.*; import java.net.InetAddress; /* * Known Bugs: * Message size is limited to 47 characters */ public class ChatClient { BufferedReader in; PrintWriter out; JFrame frame = new JFrame("ELECTRON Chatroom"); JTextField textField = new JTextField(32); JTextArea messageArea = new JTextArea(8, 40); byte[] keyValue = new byte[]{'5', '7', '3', '4', '5', '6', '3', '4', '9', '8', '5', '6', 'l', '9', '3', '4'}; final String ALGO = "AES"; String name; String myName; InetAddress ip = null; String errorType; /* * 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 class JTextFieldLimit extends PlainDocument { private int limit; // optional uppercase conversion private boolean toUppercase = false; JTextFieldLimit(int limit) { super(); this.limit = limit; } JTextFieldLimit(int limit, boolean upper) { super(); this.limit = limit; toUppercase = upper; } public void insertString (int offset, String str, AttributeSet attr) throws BadLocationException { if (str == null) return; if ((getLength() + str.length()) &lt;= limit) { if (toUppercase) str = str.toUpperCase(); super.insertString(offset, str, attr); } } } 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 { if ((textField.getText()).startsWith("/")) { if ("Electron".equals(myName)) { String command = (textField.getText()); out.println(command); textField.setText(""); } } else { //ENCRYPTION String encrypt = textField.getText(); Key key = generateKey(); Cipher c = Cipher.getInstance(ALGO); c.init(Cipher.ENCRYPT_MODE, key); byte[] encVal = c.doFinal(encrypt.getBytes()); String input = new BASE64Encoder().encode(encVal); out.println(input); textField.setText(""); } } catch (Exception 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. */ private 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")) { if (line.length() == 18) { line = line.substring(11); System.out.println(line); switch (line) { case "ERROR 1": errorType = "[ERROR: Name cannot be blank]"; JOptionPane.showMessageDialog(frame, errorType); System.exit(0); break; case "ERROR 2": errorType = "[ERROR: Your names 'Admin'? Seems legit...]"; JOptionPane.showMessageDialog(frame, errorType); System.exit(0); break; case "ERROR 3": errorType = "[ERROR: You have been banned]"; JOptionPane.showMessageDialog(frame, errorType); System.exit(0); break; } } else if (line.length() == 10) { out.println(getName()); } } else if (line.startsWith("NAMEACCEPTED")) { myName = line.substring(13); if (myName == "Admin") { errorType = "[ERROR: Your names 'Admin'? Seems legit...]"; JOptionPane.showMessageDialog(frame, errorType); System.exit(0); } else if (myName == "ADMIN") { errorType = "[ERROR: Your names 'Admin'? Seems legit...]"; JOptionPane.showMessageDialog(frame, errorType); System.exit(0); } else if (myName == "admin") { errorType = "[ERROR: Your names 'Admin'? Seems legit...]"; JOptionPane.showMessageDialog(frame, errorType); System.exit(0); } JOptionPane.showMessageDialog(frame, "Welcome " + myName + " (" + ip + ")"); ip = InetAddress.getLocalHost(); textField.setEditable(true); //Limits message length to 47 characters (Disabled for debugging purposes) //textField.setDocument(new JTextFieldLimit(47)); out.println(ip); } else if (line.startsWith("SERVERMESSAGE")) { line = line.substring(14); messageArea.append(line + "\n"); messageArea.setCaretPosition(messageArea.getDocument().getLength()); } else if (line.startsWith("SERVERCOMMAND")) { line = line.substring(14); if (line.startsWith("kick " + ip)) { System.exit(0); } } else if (line.startsWith("FINGERPRINT")) { ip = InetAddress.getLocalHost(); out.println(ip); } else if (line.startsWith("NAME")) { name = line.substring(5); } else if (line.startsWith("MESSAGE")) { try { //DECRYPTION System.out.println(line); line = line.substring(8); String encryptedData = line; System.out.println(line.length()); Key key = generateKey(); Cipher c = Cipher.getInstance(ALGO); c.init(Cipher.DECRYPT_MODE, key); byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedData); byte[] decValue = c.doFinal(decordedValue); String decryptedValue = new String(decValue); messageArea.append(name + ": " + decryptedValue + "\n"); messageArea.setCaretPosition(messageArea.getDocument().getLength()); } catch (Exception ex) { Logger.getLogger(ChatClient.class.getName()).log(Level.SEVERE, null, ex); } } } } private Key generateKey() throws Exception { Key key = new SecretKeySpec(keyValue, ALGO); return key; } /** * 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(); } } </code></pre> <p>ChatServer.java</p> <pre><code>package Chat.Application; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.ServerSocket; import java.net.Socket; import java.util.HashSet; /** * A multi-threaded chat room server. When a client connects the server requests * a screen name by sending the client the text "SUBMITNAME", and keeps * requesting a name until a unique one is received. After a client submits a * unique name, the server acknowledges with "NAMEACCEPTED". Then all messages * from that client will be broadcast to all other clients that have submitted a * unique screen name. The broadcast messages are prefixed with "MESSAGE ". * * Because this is just a teaching example to illustrate a simple chat server, * there are a few features that have been left out. Two are very useful and * belong in production code: * * 1. The protocol should be enhanced so that the client can send clean * disconnect messages to the server. * * 2. The server should do some logging. */ public class ChatServer { /** * The port that the server listens on. */ private static final int PORT = 9001; /** * The set of all names of clients in the chat room. Maintained so that we * can check that new clients are not registering name already in use. */ private static HashSet&lt;String&gt; names = new HashSet&lt;&gt;(); /** * The set of all the print writers for all the clients. This set is kept so * we can easily broadcast messages. */ private static HashSet&lt;PrintWriter&gt; writers = new HashSet&lt;&gt;(); /** * The set of all the print writers for all the clients. This set is kept so * we can easily broadcast messages. */ private static HashSet&lt;String&gt; bans = new HashSet&lt;&gt;(); private static String[] Names = new String[50]; private static String[] Fingerprints = new String[50]; static int array = 0; static int index; /** * The application main method, which just listens on a port and spawns * handler threads. */ public static void main(String[] args) throws Exception { System.out.println("Chat Server Activated"); ServerSocket listener = new ServerSocket(PORT); try { while (true) { new Handler(listener.accept()).start(); } } finally { listener.close(); } } /** * A handler thread class. Handlers are spawned from the listening loop and * are responsible for a dealing with a single client and broadcasting its * messages. */ private static class Handler extends Thread { private String name; private String ban; private Socket socket; private BufferedReader in; private PrintWriter out; private Integer length; private String fingerprint; /** * Constructs a handler thread, squirreling away the socket. All the * interesting work is done in the run method. */ public Handler(Socket socket) { this.socket = socket; } /** * Services this thread's client by repeatedly requesting a screen name * until a unique one has been submitted, then acknowledges the name and * registers the output stream for the client in a global set, then * repeatedly gets inputs and broadcasts them. */ @Override public void run() { try { // Create character streams for the socket. in = new BufferedReader(new InputStreamReader( socket.getInputStream())); out = new PrintWriter(socket.getOutputStream(), true); // Request a name from this client. Keep requesting until // a name is submitted that is not already used. Note that // checking for the existence of a name and adding the name // must be done while locking the set of names. while (true) { out.println("SUBMITNAME"); name = in.readLine(); length = name.length(); if (length == 0) { out.println("SUBMITNAME ERROR 1"); return; } if (name == "null") { out.println("SUBMITNAME ERROR 1"); return; } if (name == "Admin") { out.println("SUBMITNAME ERROR 2"); return; } if (name == "admin") { out.println("SUBMITNAME ERROR 2"); return; } if (name == "ADMIN") { out.println("SUBMITNAME ERROR 2"); return; } synchronized (bans) { out.println("FINGERPRINT"); fingerprint = in.readLine(); if (bans.contains(fingerprint)) { out.println("SUBMITNAME ERROR 3"); return; } } synchronized (names) { if (!names.contains(name)) { names.add(name); break; } } } // Now that a successful name has been chosen, add the // socket's print writer to the set of all writers so // this client can receive broadcast messages. out.println("NAMEACCEPTED " + name); Names[array] = name; System.out.println(Names[array]); Fingerprints[array] = in.readLine(); System.out.println(Fingerprints[array]); array = array + 1; //Announces that user is Online for (PrintWriter writer : writers) { writer.println("SERVERMESSAGE " + name + " is now Online"); } System.out.println(Names); writers.add(out); // Accept messages from this client and broadcast them. // Ignore other clients that cannot be broadcasted to. while (true) { String input = in.readLine(); System.out.println(input); if (input == null) { return; } for (PrintWriter writer : writers) { if (input.startsWith("/")) { if ("Electron".equals(name)) { //Tracks the hostname and IP address of the user if (input.startsWith("/track")) { input = input.substring(7); index = java.util.Arrays.asList(Names).indexOf(input); out.println("SERVERMESSAGE " + input + ": " + Fingerprints[index]); //Bans the user from returning until Server is deactivated } else if (input.startsWith("/ban")) { input = input.substring(5); index = java.util.Arrays.asList(Names).indexOf(input); synchronized (bans) { bans.add(Fingerprints[index]); } out.println("SERVERMESSAGE " + input + "(" + Fingerprints[index] + ")" + " is now banned"); } else if (input.startsWith("/kick")) { input = input.substring(6); index = java.util.Arrays.asList(Names).indexOf(input); out.println("SERVERCOMMAND kick " + Fingerprints[index]); } else if (input.startsWith("/deactivate")) { writer.println("SERVERMESSAGE The server is now Offline"); System.exit(0); } } } else { writer.println("NAME " + name); writer.println("MESSAGE " + input); } } } } catch (IOException e) { System.out.println(e); } finally { // This client is going down! Remove its name and its print // writer from the sets, and close its socket. for (PrintWriter writer : writers) { writer.println("SERVERMESSAGE " + name + " is now Offline"); } if (name != null) { names.remove(name); } if (out != null) { writers.remove(out); } try { socket.close(); } catch (IOException e) { } } } } } </code></pre> <p>I have tried varying the amount of text I send, adding more padding, even trying every input from 1 - 1000 in order to see if there was a pattern (there wasn't....). I have researched all over the internet but to no avail.</p> <p>Thanks for helping a Noob programmer with his 2nd program (Really.)! Have a great week!</p>
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    1. USSilver
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    1. COPlease add only your relevant code, and not everything. Nobody is interested in the graphics code if you are having a problem with encryption (I answered your question without looking at your code)
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      1. POCannot send AES encrypted messages of over 47 characters
      1. USJesse van Bekkum
    2. COSorry, I am new and couldn't figure out what code was truly relevant or not.
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      1. POCannot send AES encrypted messages of over 47 characters
      1. USSilver
 

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