private byte[] sessionKey;
    private byte[] preauthIntegrityHash;
    private static final int SIGNATURE_OFFSET = 48;
    private static final int SIGNATURE_LENGTH = 16;

    @BeforeAll
    static void setupClass() {
        // Ensure BouncyCastle provider is available for AES-CMAC
        if (Security.getProvider(BouncyCastleProvider.PROVIDER_NAME) == null) {
            Security.addProvider(new BouncyCastleProvider());
        }