// From http://code.calum.org/
		public static byte[] encryptSymmetric(byte[] plain, PublicKey publicKey){
        byte[] plainZipped  = Functions.compressByteArray(plain);
        long startTime  = System.currentTimeMillis();
    //    System.out.println("encryptSymmetric: plain length is " + plain.length + " bytes");
        byte[] raw          = null;
        byte[] encrypted    = null;

        try {
            // encrypt data with random key
            KeyGenerator kgen = KeyGenerator.getInstance(Main.SYMMETRIC);
            kgen.init(Main.SYMMETRICBITS);

            SecretKey skey = kgen.generateKey();
            raw = skey.getEncoded();

            SecretKeySpec skeySpec = new SecretKeySpec(raw, Main.SYMMETRIC);
            Cipher cipher = Cipher.getInstance(Main.SYMMETRIC);
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

            encrypted = cipher.doFinal(plainZipped);
            System.out.println("Symmetric encrypted (with " +
                    Main.SYMMETRIC + Main.SYMMETRICBITS +
                    " bits) is " + encrypted.length + " bytes");
        } catch (InvalidKeyException ex) {
            System.err.println(ex.toString());
            System.err.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!\n" +
                    "! If you see this, you've got some problems with your crypto stuff\n" +
                    "! You probably need to install the JCE extensions for strong crypto.\n" +
                    "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
        } catch (NoSuchPaddingException ex) {
            System.err.println(ex.toString());
        } catch (NoSuchAlgorithmException ex) {
            System.err.println(ex.toString());
        } catch (IllegalBlockSizeException ex) {
            System.err.println(ex.toString());
        } catch (BadPaddingException ex) {
            System.err.println(ex.toString());
        }

        // encrypt SecretKey with ASYMMETRIC
        byte[] encKey   = encrypt(raw, publicKey);
        System.out.println("Encrypted secret key is " + encKey.length + " bytes");

        // append encrypted key and encrypted data
        byte[] ret = Functions.append(encKey, encrypted);

        //return
  //      System.out.println((System.currentTimeMillis() - startTime ) + " ms elapsed in encryptSymmetric");
  //      System.out.println("encryptSymmetric: encrypted size is " + ret.length + " bytes");
        return ret;
    }