void calculateMIC_nullData() {
        assertThrows(NullPointerException.class, () -> ctx.calculateMIC(null));
    }

    @Test
    @DisplayName("verifyMIC delegates to GSS and succeeds")
    void verifyMIC_success() throws Exception {
        byte[] data = new byte[] { 1, 2 };
        byte[] mic = new byte[] { 3 };
        // No exception means success