I've found lots of info on decrypting PDF files, but none on encrypting them. What tool can do this for me?

Edit: There are two good answers below, but in my specific case the PDF was a scan, not a document that I'd created.


6 Answers 6


Use pdftk. From its man page:

Encrypt a PDF using 128-Bit Strength (the Default) and Withhold All Permissions (the Default)

$ pdftk [mydoc].pdf output [mydoc.128].pdf owner_pw [foopass]

Same as Above, Except a Password is Required to Open the PDF

$ pdftk [mydoc].pdf output [mydoc.128].pdf owner_pw [foo] user_pw [baz]

Same as Above, Except Printing is Allowed (after the PDF is Open)

$ pdftk [mydoc].pdf output [mydoc.128].pdf owner_pw [foo] user_pw [baz] allow printing

pdftk has a lot of other uses as well and is worth installing if one works extensively with PDF files. To quote from the write-up in Synaptic:

If PDF is electronic paper, then pdftk is an electronic stapler-remover, hole-punch, binder, secret-decoder-ring, and X-Ray-glasses. Pdftk is a simple tool for doing everyday things with PDF documents. Keep one in the top drawer of your desktop and use it to:

  • Merge PDF documents
  • Split PDF pages into a new document
  • Decrypt input as necessary (password required)
  • Encrypt output as desired
  • Fill PDF Forms with FDF Data and/or Flatten Forms
  • Apply a Background Watermark
  • Report PDF on metrics, including metadata and bookmarks
  • Update PDF Metadata
  • Attach Files to PDF Pages or the PDF Document
  • Unpack PDF Attachments
  • Burst a PDF document into single pages
  • Uncompress and re-compress page streams
  • Repair corrupted PDF (where possible)
  • 4
    If you wish a GUI for pdftk, you can try pdfchain that works good. For the above needing, you can use the Concatenate tab, adding only one PDF, and settings permissions options and password.
    – Stefano
    Feb 26, 2013 at 22:27
  • 1
    The most recent release of pdfchain brings a number of enhancements but isn't available from the official repositories yet. You can install it via this PPA (maintained by the developers): launchpad.net/~pdfchain-team/+archive/ppa Feb 27, 2013 at 10:33
  • 1
    I tried the first example with pdftk 1.44, and I could open the resulting PDF without a password using evince. Only after adding user_pw was the document actually protected.
    – Joey Adams
    Aug 8, 2013 at 20:43
  • 2
    @JoeyAdams owner_pw is intended to protect the pdf against modifications; the second example specifically adds user_pw to require a password to read the file.
    – carnendil
    Sep 5, 2017 at 17:43
  • If you just want a single password to open it, you can use pdftk [mydoc].pdf output [mydoc.128].pdf user_pw [baz], skipping the owner setting.
    – colan
    Mar 22, 2020 at 22:09

If you use LibreOffice and export a document as PDF (Menu > File > Export as PDF), there's the option to set a password:

enter image description here

  • Unfortunately my PDF is from a scan, but that would be a good general solution.
    – mfisch
    Feb 20, 2013 at 17:30
  • 2
    Shouldn't it still be possible since you can import images into LibreOffice and then export as PDF?
    – user25656
    Feb 20, 2013 at 17:36
  • I had a scanned document that the macOS Preview.app failed to encrypt correctly. Using LibreOffice to encrypt the PDF was the only way I was able to get this done, short of putting the doc on a linux server, installing pdftk and doing it on the CLI.
    – JinnKo
    Feb 16, 2018 at 11:29

qpdf can encrypt and decrypt pdfs. And linearize them, too.


  • decryption:
    • qpdf --password='·······' --decrypt input.pdf output.pdf
  • encryption: 256bit AES

Link to qpdf online Manual

Ubuntu Launchpad PPA


PDF Chain is an awesome tool for this. It is a GUI for pdftk


One possible solution is to use jpdf Tweak.


Master PDF Editor is a very good GUI for editing pdf also can encrypt. It also uses latest PDF standard. Used PDF Chain and Master PDF editor, both to encrypt a pdf, With PDF Chain the PDF outputed was larger and lost bookmarks, was almost double the size.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .