I would like to protect certain PDFs to prevent the text from being edited or copied. I have tried doing this with Acrobat, the Security Options when saving a file as a PDF, and a trial version of PDF Element, but in each case when I open the file in another programme, I can still copy and paste the text. What is the best way to protect a PDF?
As far as I know there is no real solution.
As you have already discovered, there are options in PDFs to determine if something can be edited or copied and much more, but this setting is only being honored by some PDF applications.
The only thing I can think of is to protect a PDF like you already have done and then to sign a PDF with a digital signature. By doing so, you can make sure that tampering with the file cannot be done without you noticing it: if somebody changes the file (like changing a setting), the signature won’t be valid any longer. But after all, this only helps you to ensure the validity and integrity of the file.
If digital data is out in the open, it is out in the open. There is nothing you can really do about it. You can only try to make it harder to get to the data. There are always means to get to data and to change data. The only solution is to encrypt the file with a secure password so that it cannot be opened without the password. Then again, nobody will be able to read the contents of the file without the password. So, that is not what you intend to achieve.
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Maybe you can send out the pdf without any ocr txt? But theoretically somebody could OCR it and then make the copies.
Yes, exactly. There are a lot of options to make it hard or tedious for users to extract data from a PDF. But none of those options will help you in the end when it comes down to people who know what they are doing. With a little time and effort you can get to everything that is inside of a PDF, no matter what.
As far as I know there is no reliable option to really protect a PDF against extracting data or copying data. And there is no other file format that achieves that. If you give digital data to somebody else, he or she will be able to get to the contents of this data.
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Thanks for clarifying that. At least I now know why it’s working.
I’m afraid I don’t know on Mac, but on Windows, PDFTK would prevent copy directly and PDF X-Change would as well, as my previous firm had to start copy locking PDF’s after a client tried to change a PDF we’d issued and then blame us for damages. PDFTK may run under Wine, but I’ve not tried it.
As others have said, it’s not a full fix but does prevent a general user from copying and pasting. Someone who wants it will be able to get it.
I’ll see if I can install PDFKT on Parallels (although the website makes no mention of its compatibility with Windows 10). The conclusion to be drawn from all this would seem to be that the security options for PDFs (apart from setting a password to open the PDF) are basically meaningless and that the various websites explaining how to protect PDFs are, at the very least, misleading.
(And in my previous post I obviously meant “At least I now know why it’s not working.”)
I would say that nothing is absolute with protecting PDFs. Someone determined to edit/change/distort they can do it. Anyone can screen shot (or picture with camera on any phone) the information so even if absolutely protected, the information is not.
BUT, it’s so much better to send PDFs of finished “products” instead of sending source documents (Word, Excel, Pages … whatever). It is much harder to change and edit a PDF that has no special “protection” or encryption than to change a source code document.
But for a high level of control of the file … PDF doesn’t do it. But for mere mortals like most of us, good enough. Depends on your need.
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Would you mind sharing why you want to keep PDFs from being copied from or altered? The reason that I ask is that that it feels like this is the solution that you’ve decided upon to solve a problem, but you’re presenting it as if it’s the problem itself.
Would it be sufficient to simply detect changes? That’s infinitely easier than preventing them.
Preventing sufficiently motivated people from copying digital content is something that has eluded the entertainment and software industries for decades, though if the motivation isn’t great then the means to deter it shouldn’t be either.
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I have been uploading draft translations of certain texts to a website for publishing research, and so I am obviously happy for the material to be read. I had fondly imagined that by copy-locking the PDFs I would be able to prevent people from easily copying the text (although I realized that anyone determined enough would be able to do so), but I was clearly being naïve. I’ll just have to accept that putting material up on the Web means losing all control over it.
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It works on Windows 10, as it was on Windows 10 I was using it.
I’d drafted a batch script to password protect them just by dragging and dropping the files on to them, creating a locked file on the desktop I could issue.
I installed PDFkt Pro on Parallels and tested the security settings, but I was still able to copy and paste the text when opening the PDF in another programme. Maybe I am doing something wrong. I sent an email to the developer but have received no reply, nor have I received the promised email following my purchase of the Pro version. Makes me wonder just how above-board this company is.
Works for me with the free PDFTK Server. As a test, I printed the latest Macstories article to PDF, ran it through my batch file and tried opening in Preview and get the following message.
Script was:
pdftk %1 output %USERPROFILE%\Desktop\Secure.pdf owner_pw "MacPowerUsers" allow Printing Compress
This takes the document, password protects it and creates a new secured file on the desktop, but allows printing still.
Source and password protected files here if you want to see if it opens in Adobe. I tried Preview, PDF XChange, Sumatra PDF, Firefox and Edge.
However, this is where the comments come in that it depends on the reader, as PDF Expert will copy and paste the data and even edit.
Thanks for taking the time to explain this. Apart from a few programmes I use in Parallels, I’ve never really used Windows, and so PDFtk Server is a bit beyond me. But I tried securing a PDF with PDFtk Pro again, and this time when I opened it with Preview and tried to copy text, I was asked for a password. But as you say, PDF Expert ignores the security settings.
Any file that you can read can be copied. Just take a screenshot and OCR the picture.
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Well, there’s a difference - at least in my mind - between “losing all control” and “people being able to cut/paste the text”.
You still have potential legal remedies if people are just outright stealing your work. And applying a basic protection preventing the original PDF from being edited, as well as maintaining some sort of fixed point where your copy is available, will go a long way to prevent confusion.
If this is research you’re publishing though, don’t you want it to be quoted by others?
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Well, quoted but not necessarily copied. But it all gets a bit murky. This has at any rate made me think more clearly about what I am trying to achieve by protecting the PDFs.
Then why not use PDFtk Server for macOS?
@pubay did already “protect” the PDF using Adobe Acrobat. I might be missing something, but PDFtk should do the exact same thing as Adobe Acrobat. The issue should be the same: there are PDF properties that are essentially flags for copying not allowed or printing not allowed or whatever else. All those things have one thing in common: if the PDF viewer that opens the “protected” PDF does not honor those flags, they will not accomplish anything. There is no software that can change anything about that. Am I wrong? 
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