Hello,
Can a security feature be enabled in a Moodle online class, that restricts the usage of pdf files? The best possibility would be for students to access the pdf, see it online, and have the option to print, but NOT to save or download. Can anybody see if Moodle has this function?
Thank you. Jirka
This is not a Moodle issue, this is a browser issue and impossible to control. Plus it would make no difference - if you give them the option to print, most computers nowadays have the option to Print to Pdf so that would defeat the object. You have to realize that people are going to be able to reproduce anything that is on the web if they want to.
Hi Jirka,
This must be, if not the most asked question, certainly among the top three.
https://moodle.org/mod/forum/discuss.php?d=146425#p1115855
https://moodle.org/mod/forum/discuss.php?d=243603
https://moodle.org/mod/forum/discuss.php?d=210100
https://moodle.org/mod/forum/discuss.php?d=156458
https://moodle.org/mod/forum/discuss.php?d=176109
Or just try the search option:
Hi Jirka,
As Emma has stated, it's a PDF issue rather than a Moodle one.
Yes, you can create "view and print only" PDFs with some PDF editing tools (e.g. Adobe Acrobat). However, in order to view them, like any files, they have to be downloaded. Normally, the browser downloads them into its cache before displaying them. It's possible and relatively easy to retrieve files viewed in the browser from the browser cache.
Also, even with protected/encrypted PDFs, there's nothing to stop users from taking screen shots of the text and rendering them into text with optical character recognition (OCR) software. The same goes for photos, graphs, illustrations, etc.
It's worth noting that when PDFs are marked "Restricted" when you open them, Linux ignores these restrictions and you can do pretty much anything you want with them. I'm pretty sure that "Restricted" doesn't mean encrypted.
I hope this helps
Hi Guillermo and everyone on this discussion
(Guillermo linked to this thread from another on a similar topic).
Re: SWFs, you can put a little bit of code at the start of SWFs that detects the context and only displays the content if everything's OK. If the user has downloaded the SWF or any of a list of conditions aren't met, it won't show the content. However, SWFs are trivial to decompile (reverse engineer) using free and open source software and pull out any content from them and there's no effective way to encrypt them. One way around this is to write a SWF app that pulls the text and images directly from Moodle's database (via a back-end PHP script with user authentication) and displays them within the app. If the app isn't authenticated, e.g. downloaded, it can't load the text and content. This can also be made to work outside the browser as an app on mobile devices (Yes, iPads and Android tablets do support Flash, just not in the browser) but you may as well use ebooks in that case. Flash used to be terrible at formating and displaying text but it's got better lately.
BTW, SWFs can be made accessible; you just need to specify which objects accessibility software should read. They're not specified by default so that screen readers don't try to read everything in the SWF. You can also set the tab order for easier navigation. You can also embed/load an audio version of the text as an alternative.
Re: protecting content, I've seen copy/save/print protections on some news sites that presumably use a JavaScript solution to place the text on the web page and block some of the browser's controls. Perhaps this is an avenue worth exploring? There may be a way of modifying the Book module to incude some JavaScript protection as an option. Or have you looked into ebooks?
I hope this helps!
Hi Matt,
Great explanation. I'll just add that eBooks can also be "decompiled", or more specifically, converted into html (see Calibre for this), unless of course, they have DRM (what is DRM, DRM, controversy, living DRM-free, liberate) which, in the end, can also be removed (see here for example or this plugin).
Hi Guillermo,
When DRM is correctly implemented, i.e. they use strong encryption, it's very difficult to crack. But yes, DRM seems to raise more issues than it solves. The music industry were the first to implement it broadly and they found that it drove large numbers of legitimate buyers to piracy because they had so many problems with it.
Looks like publishers haven't learned from that and are keen to repeat the experiences of the music industry: Everything will work fine this time, honest.
Adobe's eBook format (Digital Editions?) seems to be a good tradeoff between implementing DRM that is reliable and doesn't get in average end user's way. We've had the client installed on all the PCs where I work (in our library) as several eResources publish in their format.
Hi David,
Yes, Adobe's version of DRM seems to be fairly widely used by publishers and device manufacturers. For me, after buying my first ebook, which was DRM-ed by Adobe, I had so many problems with opening/viewing it (between my PC and my ereader) and using it for learning purposes, e.g. quoting and citing short sections of text, that I decided it wasn't worth the effort. I re-bought the book in hard copy (which is much easier to bookmark pages, slip notes in, zip back and forth between different pages, etc.), and then, in order to legally and legitimately quote and cite sections of text, which is "fair use" and by no means copyright infringement, I just use my smartphone's camera with built-in optical character recognition (OCR) to copy and paste. I guess you can scan texts in the same way on ereaders too.
Sure, ebooks are convenient for reading novels and maybe magazines but when you want to use texts for learning purposes, with the added obstacles from DRM, I don't think it's a workable solution. Not in my case anyway. Buying the hard copy means I own the book forever and it's not dependent on Adobe and whoever else they have contracts with for me to read it. You can't lend or sell your books. There's no second-hand ebook stores so that you can find out of print books. What if the publisher goes bust? What if Adobe or the publishers get taken over/change management/ change their policies? You soon realise that your personal library isn't actually yours.
If you think I'm being unreasonable or paranoid, in a fit of irony, Amazon remotely deleted its users' copies of George Orwell's books from their Kindles, including Nineteen Eighty-four, (which in many countries are in the public domain, i.e. the copyright has expired) http://www.slate.com/articles/technology/technology/2009/07/why_2024_will_be_like_nineteen_eightyfour.html Down the memory hole!
Amazon can and does do this. According to Amazon's actions and not their PR:
I think for these reasons and others, the majority of people don't really trust ebooks and ereaders and would rather have hard copies (The percentage of sales of books on ebook has levelled off at a small percentage. Amazon's figures claiming that ebooks have overtaken hard copy are narrow and misleading, i.e. it's Amazon's own sales figures, not the overall publishing industry's). If you can print out a PDF/HTML page/text file, you can do so much with it that is useful for study; margin notes, highlighting, folding corners, slipping in extra pages, etc.
The Kindle tablet has been universally slammed in education I gather. And all I trust apple to do is sell me songs.
I buy physical things off amazon, but digitally, unless it was an MP3 (so no drm for them to remotely destroy it) then nah.
Couldn't have said it better. Indeed, the 1984 case is as representative as it can of the underlying situation. Hopefully, at some point in time industries will learn and then stop "protecting" info. People who is going to buy is going to buy, and people who isnt, well, they won't; there's no way around it. Anyway, kind of a game actually, but in the end, those who crack the codes outnumber those that create them, so this by itself should be more than enough to know that they are spending time and money in a lost cause.
Yes, for some type of content nothing will beat physical books; I still remember having the whole table filled with open books while doing some reaserch. And of course, nothing will ever substitute the sensorial experience of a book, its smell, its texture or everything behind its design. For other uses, however, well, ebook readers are just like heaven sent! I carry my whole study library in it, I don't strain trying to read small prints and I can read in any lighting situation.
For research papers, which are almost always published as PDFs, I tried very hard to make them work on my ereader (a Kobo). I also checked out other ereaders from Amazon, Sony, iRiver, etc. and Kobo were by far the best for PDFs. Even then, it wasn't really usable. I ended up printing them out, and that's considering that printers were sent from hell to make us miserable: http://theoatmeal.com/comics/printers My guess is that newer tablets would be more suitable for PDFs.
The technology for portable reading/studying devices still has a long way to go.
PDF are not the best option as they were designed for other purposes. As I wasn't familiar with epub, etc., my first attempts were to use them, first on a Kindle Fire and then on a Whitepaper. Not a waste of time, one always learns by doing and testing, but it became clear that I better learn about real ebook formats.
Printers sent from hell? Indeed! LOL :D
This is my favourite epub editor: https://code.google.com/p/sigil/
Later versions of http://calibre-ebook.com/ include some ebook editing facilities.
I think using both benefits from some knowledge of how HTML works. Ebooks are simply HTML pages + directories of files; images, CSS, etc.; in a zipped, compressed package.
Yes, that was my first, very good, surprise! Basic HTML One just needs to get familiar with OPF & NCX files to handle both, ebook metadata and some ebook reader options. I use Calibre, mainly for converting from MOBI to AZW3. I've been wanting to play a bit with Sigil but so far I haven't made some time for that... I need to clone myself
Thank you, everybody for your responses. This is very helpful!
With appreciation,
Jirka
