About security in dwg files...

[Anonymous]

Hi

I am an Computer Forensics Expert, and my question is:

Can I know if an Autodesk file has been copied (plagiarism)?

If so, how can I prove it?

Thanks!!

[jggerth · Accepted solution]

Know well enough to stand up in court? Do you have the alleged original and the alleged copy?  Or do you just have the one you think my be a copy?

If the former case, I would look into examining the Handles assigned to the objects in the drawing. Handles are persistent across drawing sessions, and are unique within a dwg file.  Since they are sequentially assigned as entities are created, matching objects with matching handles in two different DWG files would be a red flag that one file was copied from another.  You can see individual handle sif you LIST an object in the drawing, but a comparison  between multiple drawings will either take hours/days, or programming.

Now bear in mind that a _negative_ result does not disprove plagiarism -- copy and paste from one open dwg  into another open dwg will result in the copied entities getting new handles in their new dwg file, and it's possible to completely nuke handles in a drawing.

But if 99% of the entities in A.dwg are matching geometry and handles with counterparts in B.dwg, then it's a sure bet that B was copied from A at the file system level.

[john.vellek]

Hi @Anonymous,

Did @jggerth, excellent description help you?

IMHO it is very difficult to prove conclusively that a file has been plagiarized. In addition to handles, I like to check for errors that are consistent between drawings.

There are also utilities that will help you compare drawings such as DWG Compare (from the Autodesk App Store) that might highlight the differences in drawings.

Please select the Accept as Solution button if my post solves your issue or answers your question.

[scot-65]

We place in our files a dictionary entry who's name is
the same as our menu system. Copy-clips do not
transfer over this information but a save as does.
Embedding occurs on the first instance of QSAVE.

It is not foolproof, but it seems to do the job. However,
we have had no instance (yet) where we needed to pursue
the matter.

For Thought:
I have on several occasions WBLOCK part of a surveyor's
file to use as underlays to our work. If I explode this block
while in the destination file, the engineer's work is
subsequently associated to the dictionary item of the
destination file. Did I plagiarize?

And welcome to these Forums.

???

[Anonymous]

Thanks in advance... This might let me decide which procedures need to be
taken to improve my results. 

I only have one file to search. My main strategy now is thinking that is almost impossible that two big projects can be done

at the same time using several tools... simultaneously??  (sure).

Now what I will need to do is get other crossline references in the file and, maybe, ask to have the other file in order to get the matchings.

And yes, I have some experience (5 years) working as Expert in Forensics in my Country (Mexico) in several cases.