Understanding Password vs Certificate security

Question

Howdy,
A client is currently using password-protection on all the PDFs on their website. Visitors can download PDFs, print them, copy text, they just can't edit the PDFs. Someone in their organization forgot the password -- rather than retrieving it from someone else in the organization they used a PDF password-removal tool. Now the organization is wondering if they need to step up their efforts since these password removal tools exist.
Would certificate encryption work in their case where where their site visitors could still view/print/etc. just not edit the PDFs? What if someone inside the organization needs to unlock it for whatever reason? Is it a pain to get them the appropriate certificate with the permissions to edit the PDF? I'm not sure I'm asking all the right questions...
Thanks!

Answer 1

In your case you are talking about the 'permissions' restrictions on a PDF, so the file can be opened by everyone but has controls on printing, copying, etc.*
First thing; password-based permissions settings are not secure at all. It's trivial to remove them, and only Adobe software guarantees to respect them in the first place. They're an illusion of security which tends to convince most people not to bother trying to bypass the restrictions, but if someone wants to it'll take them 30 seconds.
Certificate-based encryption uses the digital ID of the recipient, not the creator - so it's only going to work if you get the digital ID from each recipient in advance, and cannot be used for public documents on a website. It can also be removed without access to the private key, but it takes a lot more effort to do so.
Digital rights management (using Adobe ADEP / LiveCycle Rights Management servers) can protect a file against printing and direct copying with no realistic possibility of the protection being removed, but it's extremely expensive.
However in every case, if a page is visible on screen it can be captured as a screengrab, then re-OCRed to extract text. You can't extract media, scripts and vector objects, but something like a novel is utterly impossible to secure against copying if it's distributed into an uncontrolled space.
*The 'open file' security on a file is another matter entirely - even password encryption is secure enough to be uncrackable in any real-world scenario, provided you use a complex string to prevent brute-force attacks.