byte[] result = hmac.engineDigest();

        assertNotNull(result);
        assertEquals(16, result.length);
    }

    @Test
    void testHMACT64WithEmptyKey() {
        // Test with empty key
        byte[] emptyKey = new byte[0];
        HMACT64 hmac = new HMACT64(emptyKey);
        hmac.engineUpdate(TEST_DATA, 0, TEST_DATA.length);