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I have added images to a PDF and I have protected that PDF with password, so the only think, in theory, that I have authorized is printing.

Even so I open that PDF on Preview, click on any image, CMD C and CMD and I can copy that image easily.

I know that anyone can take a screnshot of that document and copy the images, but here is the point. The images are irregular and have transparency and they are over a background with an irregular pattern, so, if someone takes a screenshot will have a hell of a job to separate the stolen image from the background, so it can be used on other contexts. But if the image can be selected on Preview, copied and pasted, stealing the images are a piece of cake.

Yes, I have closed and opened the document, after protecting it. I am aware of this bug.

What kind of protection is this offered by Adobe Acrobat?

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  • Or is it a bug in Apple’s implementation of PDF?
    – WGroleau
    Commented Dec 19, 2020 at 8:00
  • Flatten the images together before making the PDF.
    – benwiggy
    Commented Dec 19, 2020 at 10:02
  • Convert PDF to a JPEG and back into PDF.
    – Bakuriu
    Commented Dec 19, 2020 at 16:17
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    You might edit words out like ridiculous. Technology is what it is, only people and their expectations typically are ridiculous. Good thing we can ask for help and edit and change when we need to grow and learn.
    – bmike ♦
    Commented Dec 19, 2020 at 17:57

5 Answers 5

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The entire suite of options within Adobe's PDF apps is pretty much optional to any other PDF-capable app. There's no way to truly lock a file.

Stack overflow has a list of ways to bypass protection -

How to remove security from a PDF file?

Another is 'just find an app that doesn't respect that particular aspect of protection'. You found one, Preview, there are many more.

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You shouldn't rely on that feature for serious protection of your document. It is simply not possible to restrict access to the image by third party software if you still want the user to be able to view it. I.e. it is not really a bug in Preview, it is a limitation in what's actually possible for Adobe to enforce.

You could take a screenshot of the final, composed product and use that in the PDF instead of your original material. That way the image will be blended together with the rest and cannot as easily be separated again.

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I work in Information Security and always say that once someone can put their eyes on some information, it is gone. There is absolutely no way to prevent the data from leaking if there is such a will.

You can screenshot it, you can learn by heart, you can make a photo - whatever.

The only two protections you can expect is confidentiality against the ones that do not have the (wisely chosen) password of an encrypted file, or integrity of a correctly digitally signed document.

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It seems like you're more concerned about protecting the graphic design elements of your PDF, and not so much about protecting any classified information included the PDF, correct?

If that is the case, I recommend flattening all design elements first (without including text), then export to PDF. This will turn convert all graphic elements into a single image so that none of the design elements can be pulled apart. Next, import the flattened PDF into InDesign (or whatever program you're using), add all text elements over it and re-export.

Let me know if this helps.

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  • One more note, you can always just flatten the whole PDF and that way nothing can be extracted, not even the text. (Unless they run some OCR tool but that only impacts the text, which you seem less concerned about anyway.)
    – BrienneOTarth
    Commented Dec 20, 2020 at 10:52
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To secure your image, you need stronger protection than PDF can offer. Why not use Apple technologies instead of Adobe for this?

Put any insecure document format in a secure disk image.

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  • That does not help in this case as the OP wants the user to be able to print the document (perhaps see it) but not to be able to copy it.
    – mmmmmm
    Commented Dec 19, 2020 at 18:38
  • It also doesn’t help cross platform either @mmmmmm but their premise that PDF was in any way adequate needed a solid, “get real encryption” answer IMO. There are legitimate trade offs to secure an image.
    – bmike ♦
    Commented Dec 19, 2020 at 18:52
  • Yes but your solution I don't think deals with the user's case - @Woj has the better naysaying answer. I think we all agree that there is no technical way to allow protection and also access
    – mmmmmm
    Commented Dec 19, 2020 at 18:55
  • @mmmmmm woj doesn’t show how to encrypt and waves hands at it. I +1 their answer since I agree. I didn’t want to edit my solution in their answer.
    – bmike ♦
    Commented Dec 19, 2020 at 20:01

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