The .DWFx files can be digitally signed with the CMS IntelliCAD 12.1 software or higher through the Attach Digital Signatures software included in the CMS IntelliCAD installation and a smart card reader.
To do this, the following steps must be performed:
a) Search for Attach Digital Signatures through Windows search;
b) Add the desired .dwfx files;
c) Select Qualified Digital Signature EC of the Citizen Card;
d) Click on Attach;
e) Enter the signature password upon request;

Such .DWFx files can be viewed with Autodesk Design Review software and Microsoft XPS Viewer.

How to install Microsoft XPS Viewer on Microsoft Windows 11:
a) Click Windows Key + i
b) search for "optional features"
c) Add an Optional Feature > View Features
d) search for XPS viewer and proceed with installation.

Prior to CMS IntelliCAD 12.1 .DWFx files obtained from CMS IntelliCAD software can be digitally signed using the free Microsoft XPS Viewer software available on Windows 10 or Autodesk Design Review 2013 software (no longer available from Autodesk);

However, you may need to add the digital signature function to the XPS Viewer viewer menu.

To do this, you must perform the following instructions:

a) run REGEDIT command at the Windows 10 search box;
b) select the folder HKEY_CURRENT_USER> Software> Microsoft> XPS Viewer;
c) in the right pane of the window, right-click and select New > DWORD (32-bit)
d) as key name type EnableDigitalSignatures
e) double click on this key and enter the value 1
f) close the Registry file edit window
g) run the XPS Viewer software and find the digital signature button available in the menu.
h) open the .DWFx file and add your digital signature to the .DWFx file

Important Note: The digital signature made using Microsoft XPS Viewer software can only be verified by third parties also using the free Microsoft XPS Viewer software.

Digitally signed documents through this process cannot be refused by public authorities where digital signature is required.

Alternatively, CMS IntelliCAD 9.2 software lets you sign .DWG files