* @throws GeneralSecurityException if cryptographic operations fail
     */
    public static byte[] calculateMacArcfourHMACMD5(int keyusage, Key key, byte[] data) throws GeneralSecurityException {
        int ms_usage = mapArcfourMD5KeyUsage(keyusage);
        Mac mac = Mac.getInstance("HmacMD5");
        MessageDigest md = MessageDigest.getInstance("MD5");
        mac.init(key);
        byte[] dk = mac.doFinal(MD5_CONSTANT);
        try {