I need to password protect my PDF file(s), because I am going to send them through email and I want anyone who would view my PDF file(s) to be prompted for a password.

How can I add a password to a PDF in Linux Mint 17.1?

6 Answers 6


You can use the program pdftk to set both the owner and/or user password

pdftk input.pdf output output.pdf owner_pw xyz user_pw abc

where owner_pw and user_pw are the commands to add the passwords xyz and abc respectively (you can also specify one or the other but the user_pw is necessary in order to prohibit opening).

You might also want to ensure that encryption strength is 128 bits by adding (though currently 128 bits is default):

.... encrypt_128bit

If you cannot run pdftk as it is no longer in every distro, you can try qpdf. Using qpdf --help gives information on the syntax. Using the same "values" as for pdftk:

qpdf --encrypt abc xyz 256 -- input.pdf output.pdf

pdftk depends on old libraries, and so is no longer in the repos of Fedora / CentOS. As a replacement, I prefer qpdf

qpdf --encrypt [readpass] [ownerpass] 256 -- [infile].pdf [outfile].pdf
  • I used Docker to overcome. askubuntu.com/questions/1028522/… Jun 12, 2018 at 20:19
  • 1
    It seems that Evince (document reader) version 3.18.2 can only open PDFs which I encrypted with 128 instead of 256.
    – gloschtla
    Jan 3, 2020 at 17:32
  • @gloschtla I used 256 and evince worked as expected. I'm still on Bionic, though (Ubuntu 18.04). Hopefully evince didn't go backward in newer versions. Mar 3, 2021 at 22:35
  • FWIW: on Evince-3.36.7, unlocking the 256-bit version seems to work. Mar 24, 2021 at 11:08

The pdftk toolkit allows for this type of functionality on Linux.

  • open your Ubuntu Terminal CTRL+ALT+T
  • install pdftk by using this command: sudo apt-get install pdftk
  • make sure pdftk is now installed by writing this on the terminal: pdftk. You will see a bunch of pdftk command instructions if it already installed
  • simply use this command to add a password to your existing pdf document: pdftk <source>.pdf output <destination>.pdf userpw <password>


pdftk Mydocs.pdf output Mydocs_pass.pdf userpw secretword


  • 5
    Note: For idiots like me, you have to actually type "output" Feb 8, 2020 at 0:47

You can also export an encrypted PDF file from Libre Office (File -> Export as PDF -> Security tab -> Set Passwords -> Set open password), if necessary importing your existing PDF into the Draw program first.

  • opening the non-encrypted PDF in LibreOffice Writer didn't work for me.
    – gloschtla
    Jan 3, 2020 at 17:13
  • 1
    What about LibreOffice Draw, @gloschtla?
    – James
    Jan 4, 2020 at 18:15

Using tools from the Poppler Toolset (from a package like libpoppler or poppler-tools), you can achieve this with a combination of pdftops and ps2pdf.

pdftops in.pdf out.ps
ps2pdf -sUserPassword=XXXXX -sOwnerPassword=YYYYY out.ps out.pdf

Note that to set a User (view) password, you must set an Owner (edit) password.


On Fedora, you can use pdf-stapler to set a password for a PDF file, and also perform other pdftk-like operations.

Example to set the user password (the one required for opening the file):

pdf-stapler -u QRNFFtVXA-8PqF cat input_file.pdf output_file.pdf

This is the password you think of most likely about setting a password to a PDF file.

In case you want to set the owner password (the one that defines permissions like printing, commenting, ect.), use the -o option.

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