Cannot run qpdf; invalid password

Question

I am trying to use qpdf to remove the password from a pdf file to allow me to use in in pdftk.

I am running qpdf in windows from command line using the following command;

C:\Users\myusername>"C:Users\myusername\Downloads\qpdf-5.1.2\bin\qpdf.exe" --decrypt "C:\ZZ_TEST\INPUT.PDF" -

Which returns the output

C:\ZZ_TEST\INPUT.PDF: invalid password.

As I am using qpdf to remove the password in the first place I'm not sure what next to try. I don't believe the issue is with accessing my user account as it is able to find qpdf in my directory in order to run it.

What is the error in my approach or the command I am using?

Answer 1

QPDF will remove the encryption from a pdf file without requiring the user to specify the password, but it won't remove encryption (without the password) in instances where a password is required to even open the file.

"C:\ZZ_TEST\INPUT.PDF: invalid password." indicates that the file requires a password to even open it.