* @return encryption context
     * @throws CIFSException if encryption is not supported or fails
     */
    Smb2EncryptionContext createEncryptionContext(final byte[] sessionKey, final byte[] preauthHash) throws CIFSException {
        if (!this.smb2 || this.negotiated == null) {
            throw new SmbUnsupportedOperationException("SMB2/SMB3 required for encryption");

                        }
                        SmbTransportImpl transport = getTransport();
                        this.encryptionContext = transport.createEncryptionContext(this.sessionKey, this.preauthIntegrityHash);
                    } catch (CIFSException e) {
                        log.error("Failed to create encryption context", e);