Security and printing of specific pages

[_Clint_Welsh_]

I am developing a line of publications for our company and they want them to be secure from copying but allow them to be able to print specific pages. Is this possible? If so, how?

Also, in light of an earlier post on breaking security, is there a way to prevent this? I thought 128 bit was secure.

Thanks!

[_Aandi_Inston_]

I recommend you post in the Acrobat forum, but I think you will find
the answers are no and no.

Aandi Inston

[Guest]

The answers are maybe (but with a fair bit of hassle) and it depends.

For Acrobat and Reader permissions apply to a document as a whole, ie there are specific page level permissions. However if you split the documents with pages that can be printed, and documents with pages that can be printed. You can the combine the two (or more than two depending upon how you split it up) document back into a package (From Acrobat 8 - File->Combine Files..., Select Documents, when asked to either Combine into single PDF or put into a Package, choose Package). The resulting file will only work well in Acrobat 8 and above and the user experience may not be what you were hoping for, but I'd play with it to find out.

Now if for the question of it is secure - it depends. The key length used is beside the point for DRM because the key to decrypt the content must exist on the user's machine which means this is a clear example of the currently unsolved CS problem of running trusted code on an untrusted host. (ie the strength of the algorithm doesn't matter because the attack comes through key recovery not through brute forcing the algorithm). For Password security on PDF files where you choose to only use a Permissions password and not an Open password (the most common case for over the Web distribution with some protection), this is actually worse, since the algorithm to generate the password to open the file in this case is published as part of the PDF Specification and because of this there are any number of tools available to remove permissions on these files. (If you have an open password this is still as secure as the combination of the password you used and the underlying algorithm).

Since perfect DRM is not currently achievable you should think about this as more of typical IS Security problem where you should be doing threat modeling to determine the risk of exposure versus the costs of mitigation. For instance there are more expensive options (such as Adobe LiveCycle Policy Server) that would include additional capabilities (such as dynamic watermarking so you could at least tell who leaked it to the public), that may or may not be suitable for what your trying to do.

[Guest]

<p>Oops, should've proof read better. First sentence of second paragraph should read:<p><br /><quote>For Acrobat and Reader permissions apply to a document as a whole, ie there <b>aren't</b> specific page level permissions</quote><br /><p>Or to put that whole last bit better - Acrobat/Reader do not support per page permissions. Sorry for any confusion caused</p>

[_Clint_Welsh_]

Ok, you just re affirmed my suspicions. As for the watermarking, I will look into that as a possibility.

Thank you!