Bulk removing passwords from PDF documents

My payslip and related documents are sent to me in PDF format. To provide some rudimentary protection from interception, they are password protected, though the password is easily obtained by anyone who knows what the system is.

Because these are important documents, I store a copy in my personal filing system, but I don’t want to have to enter the password each time I open a file. I know I can open each file individually and then resave without a password (Preview on the Mac should do this) but I wanted a way to do it in bulk, for 10s of files, without access to Adobe Acrobat Pro.

Twitter came to my aid with various suggestions including Automator on the Mac. In the end, the approach I used employed an open source tool called QPDF, recommended to me by Scott Cross (@ScottCross79). Scott also signposted a Stack Overflow post with a PowerShell script to run against a set of files but it didn’t work (leading to a rant about how Stack Overflow’s arcane rules and culture prevented me from making a single character edit) and turned out to be over-engineered. It did get me thinking though…

Those of us old enough to remember writing MS-DOS batch files will probably remember setting environment variables. Combined with a good old FOR loop, I got this:

FOR %G IN (*.pdf) DO qpdf --decrypt --password=mypassword "%G" --replace-input

Obviously, replace mypassword with something more appropriate. The --replace-input switch avoids the need to specify output filenames, and the use of the FOR command simply cycles through an entire folder and removes the encryption.

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