this.signingKey = Smb3KeyDerivation.deriveSigningKey(dialect, sessionKey, new byte[0] /* unimplemented */);
            this.algorithmName = "AESCMAC";
            this.provider = Crypto.getProvider();
            break;
        case Smb2Constants.SMB2_DIALECT_0311:
            if (preauthIntegrityHash == null) {
                throw new IllegalArgumentException("Missing preauthIntegrityHash for SMB 3.1.1");

    }

    /**
     * Get an MD4 message digest instance.
     * @return MD4 digest instance
     */
    public static MessageDigest getMD4() {
        try {
            return MessageDigest.getInstance("MD4", getProvider());
        } catch (final NoSuchAlgorithmException e) {
            throw new CIFSUnsupportedCryptoException(e);
        }
    }

    /**
     * Get an MD5 message digest instance.

     *
     * @param config the configuration to read provider preference from
     * @return RDMA provider instance, or null if none available
     */
    public static RdmaProvider getProvider(Configuration config) {
        String preference = config.getRdmaProvider();
        return createProvider(preference != null ? preference : "auto");
    }

    /**
     * Select the best available RDMA provider

     * @param context the CIFS context for configuration
     */
    public RdmaTransport(SmbTransportInternal delegate, CIFSContext context) {
        this.delegate = delegate;
        this.rdmaProvider = RdmaProviderFactory.getProvider(context.getConfig());
        this.bufferManager = new RdmaBufferManager(rdmaProvider);
        this.statistics = new RdmaStatistics();

        try {
            rdmaConnection.close();
        } finally {
            bufferManager.cleanup();
            super.disconnect();
        }
    }
    
    public RdmaProvider getProvider() {
        return provider;
    }
    
    public RdmaConnection getConnection() {
        return rdmaConnection;
    }
}
```

### 4.4 RDMA Buffer Manager
```java

    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());
        }
    }

    @BeforeEach
    void setup() {
        sessionKey = new byte[16];