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Wil
08/07/07

PDF, commenting and Adobe Reader (and DRM)

A lot of published academic papers, like the digital copies of the ACM transactions or the ones at jstor, are in PDF format.
Usually, what many of us do when reading academic literature is to generally comment it. Whether by simply highlighting it, attaching post-it notes or by writing directly to the medium. In this case it’s in pdf format so it makes sense to be able to annotate it using annotation features supported by the .pdf format right?

Well, I hunted for free PDF readers that can at least highlight some parts and well, the best thing that I can find is Skim which is for the mac: http://skim-app.sourceforge.net/. Others have the basic pdf reading functionality but I need to pay if I want to do commenting on them.

But wait, Adobe Reader supports commenting right out of the box! The problem is, PDFs are defaulted to no comment! In other words, unless you digitally sign the pdf (Using Adobe LiveCycle or any other PDF generation utility of Adobe) and mark it as “allow commenting", commenting would be disallowed – even if you generate it using a free pdf generation utility like PDFTeX or GhostScript and don’t care about document rights!
It follows that the PDFs from e-journals cannot be commented :!:

|-| That’s DRM for ya.

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9 comments

# Scott

on 31/10/07 at 20:27

Have you found a solution to this problem? Somebody must have figured this out by now, but I've been unable to find useful suggestions.

# Wil [Member]

on 06/11/07 at 17:14

As far as I know, Apple's Preview App allows commenting regardless of permissions.

# JB

on 12/04/08 at 04:31

I need to be able to highlight using adobe reader. The document was set to: Commenting: Not Allowed, and I could NOT highlight. My son has adobe acrobat professional. All he did was open the pdf and resave with a new name. Presto, I could highlight with adobe reader. The document was now set to: Commenting: Allowed. What is weird is he did not need any creator password or anything. Now I don't want to buy acrobat professional just to do this. I understand all that happens is bit 6 in a security byte gets toggled. Surely there must be some free software that can do this. If you know, please help. (a comment here would work!)

# Wil [Member]

on 12/04/08 at 10:32

I managed to get commenting to work a bit by reading the PDF Reference manual and hacking around for a bit. Basically, you need open up the pdf in a text editor and add this string:



/Perms<<

	/UR3<<

		/Reference<<

			/TransformParams<<

				/Document[/FullSave]

				/Annots[/Create/Delete/Modify/Copy/Import/Export]

				/Form[/Add/FillIn/Delete/SubmitStandalone]

				/V /2.2

				/Type /TransformParams

				/Signature[/Modify]

			>>

			/TransformMethod /UR3

			/Type /SigRef

		>>

	>>

>>

Right after /Type /Catalog in the PDF.

I an alternative would probably be using www.pdfbox.org or http://multivalent.sourceforge.net. There's an option for encryption but I don't know how well it works.

# Ivan Lopez on 07/05/08 at 00:50

Hello Wil , could you please tell me which Adobe Reader version you used?. Thanks and regards

# Wil [Member]

on 07/05/08 at 14:58

I was using Adobe Reader 8.1, the above hack I posted allows commenting but doesn't allow them to be saved but recently I updated and it doesn't seem to work anymore.

The actual implementation that Acrobat uses to enable commenting is adding that string above and calculating the hash of the entire PDF, encrpyting it, encoding it in a certificate (forgot exactly what, I think it's X.509), and inserting the hex of that binary into the PDF.

# Ivan Lopez

on 07/05/08 at 23:01

Hello again Wil, I have another question, is there a way to enable comments and save locally directly in the Adobe Reader program files, maybe the registry, or those features can be enabled only by a PDF signed file?. Thanks in advance!.

# Wil [Member]

on 07/05/08 at 23:28

Well, the only sure-fire way that I know (without resorting to hackery or such) is getting Adobe Acrobat (yes, you pay for it...), open the PDF file using that and select Advanced -> Enable Usage Rights in Adobe Reader.

I've been trying to find an alternative way (I believe that this is just ridiculous...) but I'm a bit too busy for that now.

# Arthur on 14/09/08 at 05:30

Ivan and Wil: you could try Adobe Digital Editions, which allows you to "add" bookmarks to PDFs. I say "add" because the bookmarks are actually stored in Digital Editions, not in the document itself, so they don't travel with the doc if you send it to someone else.