Hi:

I am generating a pdf from LibreOffice, and the only way one can protect the output pdf from being printed or changed requires that a password be set on the document, which I don't wish to do.

I have the popler library installed, as well as most of the available GUI programs for controlling it (pdfSAM, pdfChain, pdfMod, and pdfShuffler), but can't seem to figure out how to do this.

Am I missing something obvious, or is this just not possible?

Thanks for any pointers.

Someone can correct me if I'm mistaken but I do not believe you can protect something from being printed, after all someone can capture screenshots and print those.

I'm also not sure that even if you password protect it that this will do it. Why? Many years ago one of our Marketing guys came to me to ask how he could capture text from a PDF file, because it was password protected and the company which had created it was no longer around. Whether this was allowable or not is a different question, but we found a pdf2text Linux utility which was provided in source. We tried it and found that the password stopped us. Then someone said, "Well we got the code, just find the point where it validates the password and make that always be success." That worked and we basically made a pdf2text utility which didn't require passwords.

A better protection would be that someone couldn't view it without a passphrase. But you're saying you do not wish to use any passwords. Just not sure you can attain any level of protection without a password.

To follow on from above: The only way to prevent information from being accessed is to use encryption and encryption requires keys. So, you need a shared secret to protect any information pretty much by definition. If you're not going to use a password then what will you use as the key?

All good replies, but there are certain considerations worth mentioning:

The pdf is over 400 pages, so the idea of someone using screen shots to print several pages is not really an issue ("fair use" and all that sort of thing). If someone wants to attempt printing out the entire book I would be honored to believe they think that's worth while doing, but it would be more time and cost-effective to simply purchase the print version.

The intent is not really to prevent access to the information, but to prevent wide distribution with no recompense or, even worse, someone else buying one copy and then reselling it themselves.

But thanks for the thoughts...

Most of those pdf security deals can be bypassed. I had an app that could do it. It protects only from honest people.

There really is no 100% way to protect a file that one can read or view.

I'd just put the restrictions on the file and leave it. The other protection if you could call it that would be to copyright it.

Or you have to implement some custom DRM code.