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Unprotect protected PDF files System
Various versions of Adobe Acrobat support Security settings that allow the publisher of material to disable certain features such as allowing the printing or editing of a document.

Well, it seems that OS X's built-in PDF generation capabilities can be used to bypass these features and effectively create "unprotected" PDF documents. Here's how:
  1. Open the document with Acrobat Reader (although Preview should work just as well).

  2. Choose Print and select "Save file as a PDF" from the Print Dialog's Output Options. Be sure you save the file somewhere else unless you want to overwrite the original. OS X will then generate an unprotected PDF.
Caveats:
  • The output process will be very slow. System speed probably plays a role here.

  • The new, unprotected PDF will be massive in comparison to the original! OS X's PDF generation doesn't support compression of any type. For ex: I took a 2.4 meg protected PDF document that I made and after unprotecting it via this method, it was 14.4 megs in size.
[Editor's note: I've actually used this trick a couple times myself to print reference documents that publishers decided I should not be able to print (why have a PDF manual if you're not allowed to print it??). With OS X's ability to create PDF's on the fly, I'm not sure there are any options for publishers that wish to offer protected PDF's -- any thoughts, anyone?]
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Unprotect protected PDF files | 11 comments | Create New Account
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The following comments are owned by whoever posted them. This site is not responsible for what they say.
Does this circumvent the DCMA?
Authored by: gibblehey on Jul 05, '02 12:10:10PM
From a legal standpoint, does this mean that Mac OS X circumvents the DCMA?
Isn't this the sort of thing that got Dmitri Skylarov arrested?

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Does this circumvent the DCMA?
Authored by: dexedrine on Jul 05, '02 01:05:36PM

It's an interesting academic question to say the least.

However, this is more of a side-effect than a dedicated cracking solution. Also, I have not tested this technique against documents that require passwords to view them, etc.




[ Reply to This | # ]
Does this circumvent the DCMA?
Authored by: oem on Jul 05, '02 02:21:07PM

"Also, I have not tested this technique against documents that require passwords to view them, etc."

Well,

I've generated pdf with some password via Indesign export. I've set 2 passwords : 1 for the 'autor (me)' and the second for the one who will read it. (I've not decide to put 2 pass, that's the way it is in ID2). Anyway, i've tried to open it with preview to check if protection was effective : it is.
No password are required at the opening, BUT I had white pages…nothing appearded.
I've not tried anything else, but if a pdf files is password protected it's gonna be unreadable with Preview. (I was in 10.1.4 when I checked this 2 month ago. don't know what would hapen now, and I haven't tried with other files…

oem



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Does this circumvent the DCMA?
Authored by: victory on Jul 06, '02 02:17:16PM
I doubt it. Adobe's PDF is published standard -- neither the Preview app nor any part of OSX is actively trying to 'decrypt' a locked PDF. What got Dmitri S. in trouble was that he found a weakness in the method used to protect Adobe eBook files themselves.
A few other comments:
  • The fact that the OSX 'Print->Preview->PDF' method works with partially locked PDFs is probably a reflection on Adobe's Acrobat Reader app more than anything.
  • The concept of capturing content by 'printing-to-file' is certainly not a new thing. It's just that OSX has now made this easier than ever.
  • I once knew of someone who was miffed at the inability to print/edit a locked PDF. So what did he do? While viewing the file in Acrobat, he screen-captured each page and ran the resulting files through an OCR app... But then it IS true: quite often even common sense and logic doesn't hold up in court.

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  • Only if you can print.
    Authored by: james_sorenson on Jul 06, '02 11:59:14AM

    It's nice that you'll be able to select text after this trick, but you can only do it if the PDF file allows print permissions. Otherwise, you'll never get the print dialog to begin with. I have a couple military FM documents that disable both the text-select and the print feature.



    [ Reply to This | # ]
    Only if you can print.
    Authored by: jcanepa on Jul 08, '02 02:37:27PM

    The print permission you refer to is ignored in Preview.app.



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    Other method
    Authored by: benfsmith on Jul 08, '02 10:34:32PM

    I've been doing this for years. Print to .ps file ->distill to PDF. This still works. I asked a member of the acrobat team about this at Print '01 in Chicago. He said that it would be fixed with Acrobat 5. I only have the reader. Has anyone tried this with a file that has definitely been created with Acrobat 5x? (exporting to PDF from other apps doesn't count)



    [ Reply to This | # ]
    I don't think so
    Authored by: robgbne on Jul 10, '02 10:01:36AM

    The DCMA (as far as I know) is not the issue here. What is at issue is copyright, which exists on the intellectual property, not the digital image of the file. Printing to PDF does not defeat the file encryption anyway, it simply turns the print file into a PDF instead of a printer image (or Postscript file) - that's why it's so big. Heck, in OS X the file is conveted to a form of PDF for display (say Aqua).

    The only reason to lock PDFs is to stop unintentional modification. There are many ways of modifying digital files before they are printed so that an altered file, when printed, looks like an original. You can only trust digital files that have used proper encryption and encrypted hash values to guarantee they are unaltered. You can't trust a printed version of a digital file - as a last resort you can always scan it back in and use OCR to convert it to text, modify it, then print it out.

    Copyright is only breached if you re-publish the work - in part or in full - either singularly or as reproductions. Of course you can publish parts in a review or educational context, but only with proper acknowledgement of the original author.



    [ Reply to This | # ]
    One legitimate use
    Authored by: Han Solo on Jul 10, '02 03:11:34PM

    In order to save trees and weight, I often want to print duplexed two-up (i.e. four document pages on a single printer page, two per side) versions of downloaded PDF copies of journal articles. These are for my own use, so I am well within the "fair use" provision of copyright law to do so. However, since they are images of print journal pages, they "natively" print with incredibly large margins and small text in my 4-to-1 scheme. A way around this is to "trim" the margins in Acrobat (not Reader, obviously) and print the trimmed version (sometimes at a >100% print scaling). With locked files, one cannot trim the margins. To regain legibility, a trick like the one mentioned here works to create an "unlocked" version that I can trim and then print as above with reasonable margins and text sizes.



    [ Reply to This | # ]
    Unprotect protected PDF files
    Authored by: mfripp on May 11, '09 02:34:19AM

    The newer versions of Preview (at least OS X 10.5, and maybe earlier) respect the "do not print without a password" setting in PDF files, so the hint above won't work for them. However, it is possible to create a completely unprotected version of any PDF file using ghostscript. A command like this should work:

    gs -sOutputFile=MyNewFile.pdf -sDEVICE=pdfwrite -dNOPAUSE -dbatch -q MyProtectedFile.pdf

    You may need to type "quit" at the command prompt after gs finishes processing the file.

    I can't remember whether ghostscript came with OS X or whether I installed it from somewhere...



    [ Reply to This | # ]
    Unprotect protected PDF files
    Authored by: wireface on Jan 14, '11 05:10:41PM

    This is a great hint, thank you, it saved me a lot of time when no printer was in sight.



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