Modern PDF security
pdf-redact-tools
Redaction is the removal of private or sensitive information prior to releasing a document to the public. Often used in conjunction with the release of official government documents, redaction is visible in blacked out words or paragraphs. In business, redaction may also be necessary, most often when an internal document is released to the public. pdf-redact-tools
[6] aids redaction with three options. It turns each page of the PDF into a PNG file in a new directory, an operation that can also be done manually by converting a PDF into a multi-page TIF file. With --sanitize FILE
(-s FILE
), a script cleans up possibly sensitive file names, much like a bulk file renamer. However, the most useful option is --achromatic FILE
(-a FILE
), which converts color files to black and white to thwart identifying the printer a file is associated with by the use of unique printer dots – a practice that is little known to the public but widely known by civil rights groups and privacy experts [7]. This option, too, can be done manually in a graphics editor such as Gimp. However, having all these tools for redaction semi-automated and carried out by a single command is convenient. If you have trouble using pdf-redaction-tools
, which is no longer maintained, search for other Linux redaction tools online.
pdfresurrect
The main use of pdfresurrect
[8] is for viewing a file's versioning data. Using -w
, you can view the versioning history, and -q
returns only the number of versions that have been made. With -i
, you can view the objects in the file, as well as details of how the file was created and who created the file, if available (Figure 4). Any of this information could be sensitive – for instance, the versioning could be used as proof that the file was changed, or the file creator could be used to assign blame for the content. To avoid such cases, you can use -s
to scrub or redact all this information.
Modernizing PDFs
The PDF format, a relic from a more trusting age, is three decades out of date. While probably millions use its default permissions, these permissions are no longer adequate for more than the lightest of privacy and security. Today, the necessary encryption level has increased dramatically, and redaction was not even considered in the PDF standard. If privacy or security matters to you, I suggest that you use one or more of these tools with your PDFs. To do otherwise is to labor under a false sense of security.
Infos
- PDF insecurity: https://www.locklizard.com/password-protect-pdf/
- pdfcrack: https://sourceforge.net/projects/pdfcrack/files/pdfcrack/pdfcrack-0.19/
- poppler-utils: https://pkgs.org/download/poppler-utils
- QPDF: https://qpdf.sourceforge.io/
- QPDF options: https://qpdf.sourceforge.io/files/qpdf-manual.html#ref.basic-options
- pdf-redact-tools: https://github.com/firstlookmedia/pdf-redact-tools
- Printer dots: https://www.bbc.com/future/article/20170607-why-printers-add-secret-tracking-dots
- pdfresurrect: https://github.com/enferex/pdfresurrect
« Previous 1 2
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Direct Download
Read full article as PDF:
Price $2.95
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Find SysAdmin Jobs
News
-
MNT Seeks Financial Backing for New Seven-Inch Linux Laptop
MNT Pocket Reform is a tiny laptop that is modular, upgradable, recyclable, reusable, and ships with Debian Linux.
-
Ubuntu Flatpak Remix Adds Flatpak Support Preinstalled
If you're looking for a version of Ubuntu that includes Flatpak support out of the box, there's one clear option.
-
Gnome 44 Release Candidate Now Available
The Gnome 44 release candidate has officially arrived and adds a few changes into the mix.
-
Flathub Vying to Become the Standard Linux App Store
If the Flathub team has any say in the matter, their product will become the default tool for installing Linux apps in 2023.
-
Debian 12 to Ship with KDE Plasma 5.27
The Debian development team has shifted to the latest version of KDE for their testing branch.
-
Planet Computers Launches ARM-based Linux Desktop PCs
The firm that originally released a line of mobile keyboards has taken a different direction and has developed a new line of out-of-the-box mini Linux desktop computers.
-
Ubuntu No Longer Shipping with Flatpak
In a move that probably won’t come as a shock to many, Ubuntu and all of its official spins will no longer ship with Flatpak installed.
-
openSUSE Leap 15.5 Beta Now Available
The final version of the Leap 15 series of openSUSE is available for beta testing and offers only new software versions.
-
Linux Kernel 6.2 Released with New Hardware Support
Find out what's new in the most recent release from Linus Torvalds and the Linux kernel team.
-
Kubuntu Focus Team Releases New Mini Desktop
The team behind Kubuntu Focus has released a new NX GEN 2 mini desktop PC powered by Linux.