Some companies send encrypted PDF documents. If you’re a macOS user, Preview will ask you for the password each time you use quick look or open the document. Moreover, if you print that document, you’ll end up with a blank sheet of paper. At least I got it. So secure.
To print an encrypted PDF file, you have to decrypt it first.
In macOS, you may use a command-line tool called qpdf. The easiest way to install it is to use homebrew.
brew install qpdf
Then, navigate to the directory containing your encrypted PDF file and run the following command:
qpdf --decrypt --password=PASSWORD_TO_DECRYPT ENCRYPTED_FILE.pdf DECRYPTED_FILE.pdf
If you need to decrypt many PDF files which share the same password, you can use the loop. Below is an example loop in zsh shell:
for file in *.pdf; do qpdf --decrypt --password=PASSWORD_TO_DECRYPT $file decrypted_$file"; done