Best way to prevent editing of a PDF?

Question

Level 1

9 points

Best way to prevent editing of a PDF?

Hi there,

I would like to discover the best way to prevent the editing of a PDF.

Currently, I am using the "Print" button in Pages to get to the expanded "Security Options" window that allows me to click "Require password to copy text, images, and other content."

However, is there a better way to prevent editing? And does the password encryption actually stop people from "editing" a document, as opposed to just stopping them from copying parts of the file? My thinking is that it probably doesn't, otherwise there would be a "Require password to edit" button, right? Additionally, does this prevent people from extracting fonts from the PDF?

I hope to hear from you folks :-)

MacBook Pro with Retina display, OS X Yosemite (10.10.1)

Posted on Dec 11, 2014 11:27 PM

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Answer 1

VikingOSX

Level 10

123,248 points

Dec 12, 2014 11:10 AM in response to Arundel22

The password that you use to lock the PDF, cannot be the same password used to lock the copy/paste content, or allow printing.

Nothing in the PDF is accessible until the correct password is applied to open the document.

One can select as much text as they want, but pressing command+C to copy to the clipboard is intercepted with a drop down sheet requesting a password. Similarly, any attempt to print is also circumvented until a correct password is supplied.

These security intercepts persist in Preview after unlocking the PDF. Adobe Reader 11.0.10 simply disables the copy and print facilities. Here is Adobe Reader's security comments about this locked PDF:

You can open this locked PDF in Preview, but nothing is visible until the unlock password is supplied. You can attempt to edit the document, and although Preview will tell you that a copy of the PDF has been made, the immediate attempt to auto-save it will fail. A manual override to save the copy will also fail.

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Answer 2

Arundel22 Author

Level 1

9 points

Dec 12, 2014 7:25 PM in response to VikingOSX

Hi there,

Thanks for replying :-) I also appreciate that you took the time to screen grab shots from Adobe Reader! Thanks a bunch.

May I ask, however, if a password protected PDF (using the aforementioned copying-block password method) can be edited in Adobe Acrobat or any such program?

Additionally, can fonts be extracted even if the file has the password protection in place?

My main concerns here are that the fonts stay safely contained in the file and that no one can edit the PDF.

Thanks for the help so far 😀

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Answer 3

VikingOSX

Level 10

123,248 points

Dec 12, 2014 9:11 PM in response to Arundel22

I do not have Adobe Acrobat. I want to believe that Acrobat would behave the same as Reader — and respect the security measures inherent to the PDF. I have tried to use ghostscript with extractFonts.ps and it immediately errored out due to PDF security permissions. That is hopeful. Adobe Reader 11.0.10 on Windows 7 immediately requests a password to open the PDF, and attempts to print the document immediately fail.

It is my understanding that only subsets of fonts (characters actually used) are embedded into the PDF, thus attempts at extracting a complete font face would fail as it simply is not in the PDF.

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Answer 4

Dec 12, 2014 9:31 PM in response to Arundel22

The password protection does exactly what it says it will. In Preview. In Acrobat.

It can however be circumvented by several utilities, unlike the password for Pages documents themselves.

Fonts can be extracted. There are several Windows applications that do this, but I doubt they can from password protected pdfs and as Viking astutely points out they are usually incomplete, not containing all the characters. Which is why there are some truly awful examples floating around the PC world.

Peter

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Answer 5

Arundel22 Author

Level 1

9 points

Dec 12, 2014 9:32 PM in response to VikingOSX

Hi again,

May I ask if you get the same result in Ghostscript when only copying is password protected (as opposed to the entire file being password protected)?

I appreciate your help btw :-)

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Answer 6

Arundel22 Author

Level 1

9 points

Dec 12, 2014 9:41 PM in response to PeterBreis0807

Hi Peter,

Thanks for replying.

That is good to know. One reason why I asked was because I wasn't sure if the Pages password for copying prohibition (not the overall password stuff) actually locked down the fonts as well. I always thought that PDF files were frozen in place once exported, as in impossible to edit--but I'm learning that this is not always the reality.

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Answer 7

VikingOSX

Level 10

123,248 points

Dec 12, 2014 9:48 PM in response to Arundel22

My Ghostscript is command-line only.

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