Java UTF-8 Encoding/decoding is only displaying the first word

Question

i have a quick question that will hopefully be a quick fix.

I currently have a client/server program which takes input from the client, encodes this using UTF-8 into a byte Array, Encrypts the Array using AES, send it to the server, and reverses the process for decryption.

The only issue is, if the message has a space from the user, it will only display the word before the first space as the decrypted message.

E.G:

Input: Hello i am Tom

Output: Hello

But if my Input is all one word, it decrypts perfectly

Input: HelloIamTom

Output: HelloIamTom

I cannot find information on this anywhere!

Any help would be appreciated,

CLIENT CODE

 System.out.println("Please type a message to be encrypted:");
       message = scanner.next();


     //create iv array
     byte[] iv = toByteArray("a11f001ed2dec0de6e6f6e73656e7365");

     Cipher aesCipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
     SecretKey key = new SecretKeySpec(decryptedKey, "AES");
     IvParameterSpec ivParSpec = new IvParameterSpec(iv);
     aesCipher.init(Cipher.ENCRYPT_MODE, key, ivParSpec);
     byte[] encryptedMessage = aesCipher.doFinal(message.getBytes("UTF-8"));


     dos.writeInt(encryptedMessage.length);
     dos.write(encryptedMessage);

SERVER CODE

  int length = dis.readInt();//recieve length of byte array for incoming message
        byte[] encryptedMessage = new byte[length];//create a byte array to the length recieved
        dis.readFully(encryptedMessage);//fill the byte array with incoming data

        //decrypt using AES

        Cipher aesCipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");//create a cipher with correct parameters
        IvParameterSpec ivParaSpec = new IvParameterSpec(iv);//create IvParameter spec using IV provided in assignment brief

        aesCipher.init(Cipher.DECRYPT_MODE,key,ivParaSpec);//initialise the Cipher in DECRYPT mode
        byte[] decryptedMessage = aesCipher.doFinal(encryptedMessage);//create decryptedMessage and put in byte array

        String decMess = new String(decryptedMessage,"UTF-8");

        System.out.println("User ID:");
        System.out.println(uid);

        System.out.println("Decrypted Message:");
        System.out.println(decMess);

Instead of message = scanner.next(); try... message = scanner.nextLine(); — 3kings
– 3kings, Commented Feb 16, 2016 at 21:26

dur · Accepted Answer · 2016-02-16 21:36:04Z

2

See Scanner:

A Scanner breaks its input into tokens using a delimiter pattern, which by default matches whitespace.

and Scanner#next():

Finds and returns the next complete token from this scanner. A complete token is preceded and followed by input that matches the delimiter pattern. This method may block while waiting for input to scan, even if a previous invocation of hasNext() returned true.

If you want to scan the hole line, your modified client code is:

System.out.println("Please type a message to be encrypted:");
message = scanner.nextLine();

edited Feb 16, 2016 at 21:36

answered Feb 16, 2016 at 21:31

dur

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Comments

ninja.coder · Accepted Answer · 2016-02-16 21:30:52Z

0

You are doing message = scanner.next();. Instead of this you should be doing message = scanner.nextLine(); to take the complete line as input.

answered Feb 16, 2016 at 21:30

ninja.coder

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