assertThrows(IllegalStateException.class, originalHmac::clone);
        }
    }

    // Integration test with actual MD5 to verify HMAC calculation logic
    @Test
    void testHMACT64WithActualMD5() throws NoSuchAlgorithmException {
        // This test uses a real MD5 instance to verify the HMAC calculation logic
        // HMACT64 is a modified HMAC-MD5 where the key is truncated at 64 bytes