Unprotect a protected pdf

Question

I've purchased a pdf and want to highlight areas of it and add comments for my own personal reference.

I've look at its properties through Foxit Reader (running through wine), and, irritatingly, I'm not allowed to Modify the Document or Comment in the Document

The pdf is just a normal pdf is every other respect.

How can I unlock this pdf so I can modify it and add comments?

So, this has been set so by the owner of the document. Ask the owner of the document for a non-protected version. If you don't have the rights to crack the document, and you do it nevertheless, make sure that you are not get caught… — Max Wyss, Dec 13 '14 at 21:50
@MaxWyss Thankyou for your concern (really!) but I don't think highlighting the main themes of a novel is going to blow up into the crime of the century :P — Starkers, Dec 13 '14 at 21:58

score 20 · Accepted Answer · edited Jun 05 '17 at 20:56

20

If you're not averse to using the terminal, there's a package called qpdf that you can install. It's in the software center. To remove protections from your file you can use something like this:

qpdf --password=your_password --decrypt yourfile.pdf output.pdf

That should do the job. As a side note, another useful (also command line) tool to have for working with pdf files is pdftk.
Example from man pdftk:

pdftk secured.pdf input_pw foopass output unsecured.pdf

Hope that helps!

edited Jun 05 '17 at 20:56

dr_agon

113

answered Dec 13 '14 at 16:11

Turbo

316

Awesome utility for pdf's. – Akshay Pratap Singh Dec 10 '15 at 11:15
What if the file is not protected by a password, but instead a private key? – Timo Nov 22 '23 at 12:52

giannkas · Answer 2 · 2023-08-04T16:55:16.640

4

On Ubuntu 18.04 neither of two commands worked! (I don't know why). I followed the instructions to install pdftk (since it's no included in the repositories). However I figured it out (I think) in a simple way...

evince mydocument.pdf
ctrl+p
Print to File (choose a new file name (or overwriting))

That's it, I could highlight with Foxit Reader.

edited Aug 04 '23 at 16:55

answered Jun 26 '18 at 02:20

giannkas

41

Sure, but that removes any form fields and such.. – Clox Jan 12 '22 at 11:47
qpdf works fine on Mint 20.3 – ceperman Feb 22 '23 at 11:56

score 1 · Answer 3 · edited Jun 14 '18 at 14:08

1

Install Ghostscript and then run:

gs -sPDFPassword="$PASS" -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=%stdout% -c .setpdfwrite -f locked.pdf > unlocked.pdf

edited Jun 14 '18 at 14:08

David Foerster

36,264
56
94
147

answered Jun 14 '18 at 13:13

baobab33

63

score 1 · Answer 4 · answered Sep 01 '19 at 16:23

Use this zsh function:

pdf-unencrypt () {
    : "Usage: <file>
Uses ghostscript to rewrite the file without encryption."
    local in="$1"
    gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile="${in:r}_unencrypted.pdf" -c .setpdfwrite -f "$in"
}

: is a no-operations function. $in:r gets the variable without its extension. You obviously need ghostscript installed.

score 1 · Answer 5 · answered Dec 07 '22 at 10:46

I modified HappyFace's answer to work for

newer ghostscript versions
a list of files
passwords :)

Simply execute the following code in your shell (for me it also worked in a default ubuntu bash) and afterwards decrypt all pdfs in the current folder by running pdf-unencrypt *.pdf.

pdf-unencrypt () {
    : "Usage: <file>
Uses ghostscript to rewrite the file without encryption."
    echo "please type in password: (hidden prompt)"
    read -s passvar
    for in in "$@"
    do
        echo "trying to unecrypt $in"
        gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sPDFPassword="${passvar}" -sOutputFile="${in:r}_unencrypted.pdf" -f "$in"
    done
    unset passvar
}

and afterwards decrypt all pdfs in the current folder by running pdf-unencrypt *.pdf.

score 0 · Answer 6 · answered Feb 12 '23 at 07:23

Turbo's answer with qpdf was very helpful.

I just wanted to contribute a one-liner bash command for anyone looking; this will decrypt all the PDF files in the current folder with qpdf (assuming the files all have the same password):

for f in *.pdf; do qpdf --password=[your password] --decrypt $f --replace-input; done

Note that it decrypts the files in-place. To output as a new file, you would have to leave out --replace-input and maybe prepend the filename placeholder with a folder or some other distinguisher.

Unprotect a protected pdf

6 Answers6