HMACT64 hmac = new HMACT64(TEST_KEY);
            assertThrows(IllegalStateException.class, () -> hmac.engineDigest(new byte[10], 0, 10));
        }
    }

    @Test
    void testClone() throws NoSuchAlgorithmException, CloneNotSupportedException {
        // Test clone() method
        try (MockedStatic<Crypto> mockedCrypto = mockStatic(Crypto.class)) {