Unfortunately that wouldn’t work as this is information inside the PDF itself so it has nothing to do with the file hash (although that is one way to track.)
Now that this is known, It’s not enough to remove metadata from the PDF itself. Each image inside a PDF, for example, can contain metadata. I say this because they’re apparently starting a game of whack-a-mole because this won’t stop here.
It will be slow-ish and probably make the file larger, but if you’re sharing a PDF that only you are supposed to have access to, it’s worth it. MAT or exiftool should work.
Edit: as spoken about in another comment thread here, there is also pdf/image steganography as a technique they can use.
Unfortunately that wouldn’t work as this is information inside the PDF itself so it has nothing to do with the file hash (although that is one way to track.)
Now that this is known, It’s not enough to remove metadata from the PDF itself. Each image inside a PDF, for example, can contain metadata. I say this because they’re apparently starting a game of whack-a-mole because this won’t stop here.
There are multiple ways of removing ALL metadata from a PDF, here are most of them.
It will be slow-ish and probably make the file larger, but if you’re sharing a PDF that only you are supposed to have access to, it’s worth it. MAT or exiftool should work.
Edit: as spoken about in another comment thread here, there is also pdf/image steganography as a technique they can use.
Wouldn’t printing the PDF to a new PDF inherently strip the metadata put there by the publisher?
it’s possible using steganographic techniques to embed digital watermarks which would not be stripped by simply printing to pdf.
Got it. Print to a low quality JPG, the use AI upscaling to restore the text and graphs.