public static void fileEncripWrapped(File in, File out, PublicKey pub, byte [] key) {
 
        try {
            SecretKeySpec keySpec = new SecretKeySpec(key, "AES");
 
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.WRAP_MODE, pub);
            byte[] encKey = cipher.wrap(keySpec);
 
            FileOutputStream osAppend  = new FileOutputStream(out);
 
            osAppend.write(encKey);
            osAppend.close();
 
             cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
            cipher.init(Cipher.ENCRYPT_MODE, keySpec);
 
            FileInputStream is = new FileInputStream(in);
            CipherOutputStream os = new CipherOutputStream(new FileOutputStream(out, true), cipher);
 
            copy(is, os);
 
            is.close();
            os.close();
 
        } catch (Exception ex) {
            System.err.println("Ha succeït un error xifrant: " + ex);
        }
    }
 
    public static void fileUncryptWrapped(File in, File out, PrivateKey priv) { 
        try {
 
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.UNWRAP_MODE, priv);
 
            InputStream is = new FileInputStream(in);
            byte[] bufferKey = getFirstBytes(is, 256);
 
            Key ky = cipher.unwrap(bufferKey, "AES", Cipher.SECRET_KEY);
 
            cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, ky);
 
           CipherInputStream cIs = new CipherInputStream(is, cipher);
           FileOutputStream os = new FileOutputStream(out);
 
           copy (cIs  , os);
 
           is.close();
           cIs.close();
           os.close();
 
        } catch (Exception ex) {
            System.err.println("Ha succeït un error xifrant: " + ex);
        }
    }
 

 /**
     * Copy the bytes of input string to bytes in output string in blocks of 1024 bytes
     * @param is - InputStream
     * @param os - OutputStream
     * @throws IOException 
     */
    private static void copy(InputStream is, OutputStream os) throws IOException { //http://www.macs.hw.ac.uk/~ml355/lore/pkencryption.htm
        int i;
        byte[] b = new byte[1024];
        while((i=is.read(b))!=-1) {
          os.write(b, 0, i);
        }
    }
 
    /**
     * Get the first n bytes of a binary file
     * @param is - InoutStream
     * @param size - Size do you want to take. 
     * @return 
     */
    private static byte [] getFirstBytes (InputStream is, int size) {
        byte [] bytes = new byte [size];
        try { 
            if (is.read(bytes) != bytes.length) {
                is.close();
                throw new IllegalStateException("Too short file");
            }
        } catch (IOException ex) {
            Logger.getLogger(Asimetric.class.getName()).log(Level.SEVERE, null, ex);
        }
        return bytes;
    }