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RE: ACAD Protection

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We can place it on the website for download. If you will allow, I will
publish it in the March SEAINT Online which will also be posted on the
SEAINT Website.
You can send it to me for publication in Online and Shafat for placement on
the website.
Dennis Wish
Editor SEAINT Online

-----Original Message-----
From: Mark Middlebrook [mailto:markmid(--nospam--at)]
Sent: Saturday, January 09, 1999 10:54 AM
To: 'SEAOC List'
Subject: Re: ACAD Protection


>> Is it possible to enclose a coding that will produce a message on any
drawing(s) revised without authority, a bit like a hidden cookie that would
require serious hacking to find and delete? <<

There's nothing built into AutoCAD that provides any sort of drawing
protection, either locking or stamping. It might be possible to write an ARX
or VBA application that provided the functionality you describe, but if so,
I suspect that it would be a non-trivial job.

If you're worried about unauthorized editing, you can take measures such as:

- Make a note of the last updated time for each drawing (TDUPDATE system
variable or TIME command).

- Print the directory information (including date and time) of the DWG files
that you submitted.

- Make archive plots for later comparison (11"x17" reduced-size often works
nicely for this purpose, and are handy for later review).

- Again, make sure that your contracts cover what's allowed and what's not

Obviously none of these measures *prevents* anyone from editing your
drawings, but they do give you documentation that can help you prove
tampering and demonstrate exactly what you sent.

A company called CADLock ( makes a third party application
for locking AutoCAD drawings. But again, I question whether this kind of
approach is the right one for most situations that structural engineering
firms encounter. Like all proprietary copy protection schemes, it increases
the hassle factor (for oneself *and* one's clients). Moreover, the need to
lock drawings often is a sign that the engineer-client relationship isn't a
good one, or that contracts and communications haven't been attended to

Nonetheless, there's no reason that Autodesk couldn't add some sort of
simple password protection to AutoCAD, a la the Microsoft Office
applications. This feature is on the wishlist, but for whatever reason
hasn't made it into the software. You could go to the Autodesk User Group
International wishlist page ( and add your vote.

Way back in 1991 I wrote an article for CADALYST magazine on the copyright,
liability, and other legal concerns in electronic drawing exchange. If
there's interest, I can post it to the list (it's about 200 lines / 2000

- Mark Middlebrook