Encrypting CAD files, Windows Server 2003

darkbluegr
darkbluegr used Ask the Experts™
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Hi, I haven't used encryption in the past and I was wondering if it could help me with a business case we are having.

In our domain network, we recently created accounts for interns who will be working for us for a few months. We need to make sure these interns can not use the company's AutoCAD (DWG) files outside of the company network, because the drawings that they will be working on, do not belong to our company (they are provided to us because we are subcontractors working on some small parts).

Can I enable encryption on the domain for our CAD drawings folders, so that the interns and everyone else can still work on these, BUT if they copy the files to , let's say, a USB drive or transfer them over email, they will be rendered unusable (since they don't have the encryption key?)

If the above is correct can you please point me to best practices in implementing encryption (Win2003 native EFS or something else?). Our domain has 30 domain users at the moment.

Thank you
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Jason WatkinsIT Project Leader

Commented:
Hello,

Encryption aside, consider restricting access to the folders these files are located by group membership. If you haven't already, create an 'Interns" Global Group in Active Directory, and remove the 'Read" permission from the ACL of any folder that contains the DWG files.

EFS encryption does not scale well to shared-use situations.

Author

Commented:
Thank you Firebar,

The interns will need to be able to do some work on these DWG files.

Is there any way they can work with the files when inside the company's network, but if they try to steal them and use them somewhere else, the files would be unusable, since they won't have the encryption key? This is what I am trying to achieve.

Thanks again.
Jason WatkinsIT Project Leader

Commented:
Not without a piece of third party middleware. I have seen some suites that send an alert when a USB drive has been inserted, or if a file was copied to it. Location-aware encryption is fielded as prominently as are access control mechanisms.

The secure locations I have worked in, no floppies (pre-USB drives) were allowed in the rooms.

An example piece of software; http://www.monitorusb.com/

I have not used this piece in the past.

Author

Commented:
Thank you - my objective is not to disable the usb drives/floppies.

What I'm trying to do is: Allow employees and interns to use the drawing files when they are in the company's network. If they try to open the files outside of the company's network, for example at home or if they copy it to a removable media, I would like the files to be inaccessible.
I thought that EFS would do this very thing, no?
Jason WatkinsIT Project Leader

Commented:
EFS encrypts the contents of a document within the contex of a user's profile. So, yes, if someone tried to use the file at home, their home computer may not be able to open it. Are the files meant to be viewed by only one person, ever?

Author

Commented:
Hm this is a valid point - the typical case is:

user1 works on design1_rev1. after he's done, he is saving it in his department's folder, and his manager reviews it. Manager sends comments to user1 for revision.

Then user1 revises the design, saves as design1_rev2.

user1 exports the dwg to PDF for customer comments. Customer sends his comments, and user2 works on design1_rev2, and so forth.

So at any given time there is only one user working on each file.

If a user saves the file in his department's folder, his supervisor won't be able to access it since he's logging in with a different domain user account?

Thanks again.
IT Project Leader
Commented:
A Public Key Infrastructure may be more helpful than straight EFS; http://www.microsoft.com/windowsserver2003/technologies/pki/default.mspx
You can download it and use it for up to two users without having to by a CAL.

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