CADlock - Review

Geoff Harrod

In today’s design environment where CAD is taken for granted, companies often request copies of the DWG file rather than prints. This is most often so that they can extract drawing information to use as a basis for their own contracted work on that job and is quite legitimate. But often there is more information in the file than is really needed for their purpose and the drawing owner may not want to have their design data fully accessible. Sometimes, the above situation can be answered by copying just the needed data into a new DWG file. Other times that may not be practical, or the recipient may have a genuine need to insert data in their own work, but the originator may want to prevent that data being changed at all.

The desire to prevent recipients of drawing files from altering data often arises not only because of not wanting the to alter your work, but also from legal responsibility for the consequences of a job being constructed according to the details you designed. Another common situation is where firms are required to submit CAD data files in a bid for a contract. In that case it is very desirable that the data cannot be used by others but can be examined fully.

CADlock is a software system that enables DWG files to be sent to people who can open the files in AutoCAD and make use of the data in a manner and to a degree controlled by the owner of the data. It does this by translating the original DWG file into its own format which incorporates provision for adding access control by password to further restrict usage. The translated drawing files have a filetype of DWX and cannot be read by AutoCAD in its standard form. In order to open the files, the user needs to install a version of CADlock, which adds into AutoCAD the ability to use the locked files.

CADlock adds one pull-down to the standard AutoCAD menu. In addition, the Save and Open commands have DWX support added. A small toolbar is also accessible which duplicates the menu options.

CADlock SE is the full version of the system, and is needed to create CADlocked drawing files. There is also a ‘Run-Time’ version called CADlock RT which is supplied with SE and can be freely copied and distributed to recipients of DWX files. This enables them to open the files and make use of them. The SE system adds to the AutoCAD Save function, the option to include the RT program with the saved drawing file. CADlock RT can also be freely downloaded from the CADlock web site.

CADlock provides several options of security, in three basic levels. Level 1 just adds the design owner’s copyright notice. This is stored within the DWX file and cannot be altered or removed and will always be displayed when the drawing is opened or printed.

Level 2 adds passkey access control. When this is enabled, the entire drawing data is encrypted, and the DWX file can only be opened by those who know the security key or keys. The control can be either by a single password or a public/private key-pair.

Level 3 adds restrictions to what can be done with the drawing after access is gained via the passkey. This is done by disabling AutoCAD commands and API functions as specified by the owner when creating the CADlocked DWX file. The available restrictions can be seen in the Security Setting dialog box illustration.

The ‘Database Modify’ restriction disables all AutoCAD commands and functions which can change the drawing data. This includes the Properties pop-up in 2000 since you can alter data that way, and in that case has the side-effect of preventing the use of the Properties facility for just enquiring about the data.

The ‘Database Output’ restriction disables all AutoCAD commands that can save or export the data. When this restriction is not activated, all the save commands create secured DWX files with no less restriction that the original. It is never possible to create a normal unsecured DWG file from a DWX file except by usingt he full SE version and having owner’s rights.

The ‘Plot / 2D Output’ restriction disables all facilities for creating 2D output such as Plot, Export, WMFout etc.

The ‘Database Query’ restriction disables the Area, Dblist, Dist, ID, List and Massprop comamnds. It does not prevent data query via Lisp and API actions.

The ‘View Altering’ restriction disable all commands that alter the display such as Pan, Zoom, Vpoint, Pspace, Mspace, Shade, etc. I found that for some reason not expained, CADlock seems to always disable 3Dorbit even though ‘View Altering’ is not activated.

The two ‘System Level’ restrictions affect various configuration and operating system facilities. The ‘Interface Altering’ restriction prevents changing the display, menus and toolbar options and operational preferences.

This dialog box, (called from the menu or toolbar) shows what restrictions are in force. A similar dialog in SE is used to set the options when creating the DWX file.

If a CADlocked drawing file is accessible to a user and is inserted (or xref’ed) into a normal unsecured DWG file, such as one of the recipient firm’s drawings, the insertion will work but the entire drawing into which it is inserted becomes secured to the same degree as the inserted file. This facility may be useful sometimes, but because of its potential to prevent further access to one’s own darwings, CADlock displays an explanatory warning and requires confrmation when the insertion is attempted. They suggest that if this action is in fact intended, that you first save your own drawing file (without the insertion) to another name to safeguard future full access.

If you try to edit a drawing object you either get an "Unknown Command" message on the command line. The above warning dialog appears the first time such an attempt is made.

I tried out CADlock SE version 3.3 on AutoCAD 2000 with no problems. The product notes state that this version works with 2000, 2000i, LT 2000, LT 2000i, ‘most variants’ of R14, LT 97, LT98, and provides limited support for R13c4. It occupies some 3Mb of disk space. The price for a single copy of SE is quoted as US$400, CAN$600, A$680 (Australian), €440 Euros, or 42400 Yen. A site licence is about four times that. The RT version is free.

CADlock appears to answer this very real security need for CAD data extremely well and rather neatly. All the CADlock users that I know have expressed their satisfaction with the product and its capabilities.