Quote:
Originally Posted by arspr
Yes, that's what I expected. My wild guess about the crash issue is that the culprit is the AES 256bit protection. But in fact I don't know what the hell it is. The pdf is protected against certain features (even with a "password") but at the same time you can freely render it...
I've never been able to understand how this kind of protections CAN work... If I can access the content then I can access the content, how can you prevent me about doing whatever I want with it? And if it is encrypted and I cannot access it, then I cannot access it, so how can I render and display it? 
Nevertheless, it would be great if someone with full fledged Acrobat could generate a sample pdf enabling this feature... |
I don't think it has to do with the AES protection. I used Acrobat XI to generate a PDF openable with Acrobat 3 or higher and it worked. Used the same input file and set the output for Acrobat Level 8/PDF 1.7 (Acrobat X or higher) and it rebooted my Kobo. The stack error log looked the same as the one from opening the original Canon manual.
As for the value of the restriction flags, there aren't that many bits of software that can be used to edit PDF files so most people are using Adobe's Acrobat which does respect the restrictions.
At work, we do generate quite a few PDF's that are flagged as not printable by Adobe's or compatible software and others that allow form filling.
A PDF file can have two passwords set, one is the owner password which is used to enable/disable restrictions, the other is an user password which is needed to open the file for any purpose. Then you can get into the PDF compatibility settings in Acrobat -- I tend to prefer Acrobat 6 (PDF 1.5) just to make the file readable on as many systems as possible while keeping some advanced features.