public synchronized byte[] mac(byte[] message) {
        ConfidentialStore cs = ConfidentialStore.get();
        if (mac == null || cs != lastCS) {
            lastCS = cs;
            mac = createMac();
        }
        return chop(mac.doFinal(message));
    }
@Test
    public void testTruncatedMacOnNonFips() {
        HMACConfidentialKey key1 = new HMACConfidentialKey("test", 16);
        String str = key1.mac("Hello World");
        String pattern = "[0-9A-Fa-f]{32}";
        assertThat(str, matchesPattern(pattern));
    }