Episode: 4016
Title: HPR4016: Today I learnt
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr4016/hpr4016.mp3
Transcribed: 2025-10-25 18:37:56

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This is Hacker Public Radio Episode 4,016 from Monday the 25th of December 2023.
Today's show is entitled, Today I Learned.
It is hosted by Mr. X and is about seven minutes long.
It carries an explicit flag.
The summary is, Today I Learned How to Remove a Password from a File.
Hello and welcome, Hacker Public Radio Dance.
My name is Mr. X and welcome to this podcast.
As usual, I'd like to start by thanking the people HPR for making the service available
to us all.
HPR is an invaluable service on these hidden tubes.
It's a community-led podcast provided by the community for the community.
That means you could contribute to, why don't you pick up a microphone or your mobile
phone, tablet, whatever you've got to hand, record a show and send it in.
We're always looking for shows and I think right now we're about shortening shows.
For information, it's Sunday the 17th of December.
I'm currently on holidays, I've wee bit of spare time on my hands and I was just
asking to show Dave Morris sent in HPR for 002 where he proposed to start a new series
called, Today I Learned.
I was thinking, well, actually there was something I just did recently and I thought that's
a perfect candidate.
I'm not going to a lot of detail, I'm no expert in the topic I'm going to cover, but hopefully
somebody will find this interesting.
I came across a PDF which I wanted to mark up just for reference purposes just so that
I could look at it and quickly see points of interest within this PDF and I found that
I was unable to do that because the moment I tried to mark up, it was asking me for
a password.
And of course, let's just say I'd forgotten the password.
I initially thought I could have used this and maybe it didn't look at it in enough
detail.
Dave mentioned to me that there's a fantastic application called, I don't know how you
would say, O-K-U-L-A-R, Ocula and it's great for marking up and splitting PDFs and all
sorts of stuff like that.
I'm looking at it briefly, I couldn't see a way to solve the problem with that so I did
my usual googling.
And I came across a web page and it gave various suggestions about how you can solve this.
And the option that worked for me was the command line program, QPDF, now looking at the
command page for QPDF, when does it say QPDF is a QPDF transformation software.
The QPDF program is used to convert one PDF file to another equivalent PDF file.
It is capable of performing a variety of transformations such as linearization, also known as web optimization
of fast web viewing, encryption and decryption of PDF files.
It also has many options for inspecting or checking PDF files, some of which are useful
primarily for PDF developers.
For a summary of QPDF's options, please run QPDF dash dash help.
A complete manual can be found in user share.qPDF, QPDF manual.html or as a PDF version as
well in user share.qPDF, yeah.
The version was at say version 8028.0.2 April 2008 is the one I'm currently running on my PC
here.
So I ran the QPDF with a dash dash help flag and sure enough, dash dash decrypt, remove
encryption on the file.
So basically to do that, you just do QPDF space dash dash decrypt space and give the name
of your input file protected, it says here example protected protected.pdf and then you give
your new file name you want unprotected.pdf, hit the turn, bam, done.
Now I noticed down in the comments further down that Evan Gard back in 2016 noted a
that it won't work if you don't know the user password.
Owner password is only for enforcing restrictions, user is for opening the file and to be able
to view it.
So I guess it depends what security settings the person set when they protect it.
You could make it such that you could only view it if you know the password at the user
password.
So I was able to view this document, I just couldn't mark it up.
So yeah, so owner password is only for enforcing restrictions.
So I was able to mark up to my heart's content after issuing that.
So I thought that was a handy tip if you're ever in that situation.
Don't know if there's much else I have to say on that, yeah I think that's about it.
Well, I wish you all a very Merry Christmas, depending on when you listen to this, and
I'm happy new year and others to you and your family.
And if you've got a spirit minute, when you're off final to send in a show, you can just
do something and prompt you like this, as I've done, now it said, it doesn't take very
long and I'm sure we'd all find it interesting.
Okay, thank you very much, all the best, oh oh finally, I'm so rusty that I forgot and
need to say, if you want to contact me, you can contact me at MrX at hpr at googlemail.com
that's MrX MRX AT, hpr the at symbol googlemail.com, hope I've got that right.
So until next time, hopefully a bit sooner than it's been off late, thank you and goodbye.
You have been listening to Hacker Public Radio at Hacker Public Radio.org.
Today's show was contributed by a hpr listener like yourself.
If you ever thought of recording podcasts, you click on our contribute link to find out how
easy it really is. Hosting for hpr has been kindly provided by an honesthost.com,
the internet archive and rsync.net. On this otherwise status, today's show is released
under Creative Commons, Attribution 4.0 International License.
