All your problems derive from this
byte[] encrypted = cipher.doFinal(toEncrypt.getBytes()); return encrypted;
Which are enclosed in a try, catch block, the problem is that in case the program found an exception you are not returning anything. Put it like this (modify it as your program logic stands):
public static byte[] encrypt(String toEncrypt) throws Exception{ try{ String plaintext = toEncrypt; String key = "01234567890abcde"; String iv = "fedcba9876543210"; SecretKeySpec keyspec = new SecretKeySpec(key.getBytes(), "AES"); IvParameterSpec ivspec = new IvParameterSpec(iv.getBytes()); Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding"); cipher.init(Cipher.ENCRYPT_MODE,keyspec,ivspec); byte[] encrypted = cipher.doFinal(toEncrypt.getBytes()); return encrypted; } catch(Exception e){ return null; // Always must return something } }
For the second one you must catch the Exception from the encrypt method call, like this (also modify it as your program logic stands):
public void actionPerformed(ActionEvent e) . . . try { byte[] encrypted = encrypt(concatURL); String encryptedString = bytesToHex(encrypted); content.removeAll(); content.add(new JLabel("Concatenated User Input -->" + concatURL)); content.add(encryptedTextField); setContentPane(content); } catch (Exception exc) { // TODO: handle exception } }
The lessons you must learn from this:
- A method with a return-type must always return an object of that type, I mean in all possible scenarios
- All checked exceptions must always be handled