how to decrypt in java (snippet of my code included)

I am wanting to create a functional Java chat application. So I have a small application which allows users to connect via server classes and talk with each other via client classes and I have started to add Encryption. I am having trouble decrypting output from other clients in my Java chat application.

can someone help me please?

snippet of my code is included below:

THE CLIENTGUI.JAVA CLASS (encrypt is a button which is clicked)

if(o == encrypt) { String change = null; try{ change = tf.getText(); change = FileEncryption.encryptString(change); tf.setText("" + change); return; } catch (Exception e1) { // TODO Auto-generated catch block e1.printStackTrace(); } finally{ } 

THE FILEENCRYPTION.JAVA

public class FileEncryption { //Initial Vector public static final byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; //EncryptAndDecrypt String -> Input : PlainText + Return : CipherText+DecipherText public static String encryptString(String src) throws Exception { String dst=""; //Not Input! if(src == null || src.length()==0) return ""; //Encryption Setting byte[] k="Multimediaproces".getBytes(); SecretKeySpec Key = new SecretKeySpec(k,"AES"); IvParameterSpec ivspec = new IvParameterSpec(iv); Cipher encryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); encryptCipher.init(Cipher.ENCRYPT_MODE,Key,ivspec); ByteArrayOutputStream baos = new ByteArrayOutputStream(); CipherOutputStream cout = new CipherOutputStream(baos,encryptCipher); cout.write(src.getBytes()); cout.flush(); //ByteOutputStream -> Write Encryption Text cout.close(); // in encrypt method dst = DatatypeConverter.printHexBinary(baos.toByteArray()); return dst; } //String src -> EncryptedData public static String decryptString(String src) throws Exception { //src value is Encrypted Value! //So, src value -> Not Byte! String dst=""; byte[] encryptedBytes = DatatypeConverter.parseHexBinary(src);; //Not Input! if(src == null || src.length()==0) return ""; //Decryption Setting IvParameterSpec ivspec = new IvParameterSpec(iv); byte[] k="Multimediaproces".getBytes(); SecretKeySpec Key = new SecretKeySpec(k,"AES"); Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); decryptCipher.init(Cipher.DECRYPT_MODE,Key,ivspec); ByteArrayOutputStream baos = new ByteArrayOutputStream(); ByteArrayInputStream bais = new ByteArrayInputStream(encryptedBytes); CipherInputStream cin = new CipherInputStream(bais,decryptCipher); byte[] buf = new byte[1024]; int read; while((read=cin.read(buf))>=0) //reading encrypted data! { baos.write(buf,0,read); //writing decrypted data! } // closing streams cin.close(); dst = new String(baos.toByteArray()); return dst; } } 

the problem is that when i try to decrypt the code entering the following code: if(o == decrypt) {

 try{ msg = tf.getText(); msg = FileEncryption.decryptString(msg); fop. } catch (Exception e1) { // TODO Auto-generated catch block e1.printStackTrace(); }finally{ } 

Currently, it ALLOWS me to encrypt what I type into text field.

It does not allow me to decrypt the output of what the users have said in the chat. The current code I have included for the decrypt does not function.

Can anyone help me? or have any suggestions that I could make to my program to help it decrypt?

Thanks

EDIT: