How to remove a password I know from a PDF, with no degradation, on Linux?

Question

Someone sent me a password-protected PDF. I know the password, but I want to make the PDF password-less, for convenience.

However - I want to make sure I don't lose any of the information in there. For example, I don't want images to be resampled, or vectorized content rasterized, or text runs/paragraphs broken up, or ancillary/non-critical non-printing data to be lost, I want the document properties meta-data to stay the same (well, perhaps I'm a little flexible about that).

Also, since I'm not a PDF format wiz, I'm not sure I can tell when a PDF has been degraded. So, for example, if I print to PDF from a PDF viewer, I'm not sure if the result is satisfactory - until perhaps someday later I'm trying to import it in a document editor or select some of the text and then find out something has changed.

My question is: Is there a way for me to do this which is qualitatively better than printing to a PDF? Perhaps I can simply remove the password somehow, in-place? Or at least ensure maximum-conservatism in the processing?

Notes:

• I'm using Devuan GNU/Linux 3.0 (which is about the same as Debian Buster).
• There's a near-duplicate question, Removing the password from a PDF file - but the answers there are Windows and Mac utilities.
• I've tried using pdftk ... input_pw, but that doesn't work.