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In the replies to how to remove the password from a pdf file, some solutions (e.g. by ghostscript) require no password, while some (e.g. by pdftk) do.

Is knowing the password necessary for removing it from a pdf file? If not, then

  • why do some solutions (e.g. by pdftk) require the password? What are their advantages over those solutions that don't require the password?

  • what is the purpose of setting up a password for a pdf file? Does it try to prevent those without the password from reading and writing the pdf file? Does it prevent those without the password from printing/copying the pdf file to another pdf file without any password, an indirect way to read the original pdf file, and the idea of the pdftk and ghostscript solutions?

Tim
  • 26,107

2 Answers2

2

One may try to use programs that try to guess the password of the PDF file via bruteforce, e.g. pdfcrack:

sudo apt install pdfcrack

If the password is just for editing the PDF, one can view the PDF file in some PDF viewer e.g. with Chrome's built-in PDF viewer, and print it as a PDF file. The new PDF file won't have any password.

Franck Dernoncourt
  • 3,548
0

If the PDF file has a password on it, you will need to know the password to remove it.

Mr. T
  • 201