Selling PDF books, files, documents online with DRM copy protection

Using DRM to protect PDFs sold online.

Selling PDF books, files and documents online has obvious advantages.  You can cut costs (no more printed copies to produce and distribute), help save the environment (no more paper), save time (distribution handled automatically by an ecommerce system), and reach new markets.  The downside however is how do you protect electronic copies which by their very nature can be easily re-produced?

David Edgar, in his 1971 play ‘The National Interest’ famously said, “You never appreciate what you don’t pay for.”

Nowhere could that be more true today than on the Internet, where unqualified content is all there for the taking.  And if the content creators don’t mind not getting paid for what they do that is fine.  But you would have to wonder what is paying them to keep going.

Back in the days of Tom Paine and John Stuart Mill authors needed to be paid for their content because otherwise they could not afford to write.  Where would that have put ‘The Rights of Man,’ or ‘On Liberty,’ in the brave new world, I wonder?

So the problem with selling PDF books, files, or documents on the Internet, is preventing misuse by recipients.  A lot of people claim that there is no copyright on the Internet (well they would say that, wouldn’t they) if they think that they have the right to copy and redistribute as and how they see fit.  Well, it’s not their livings they are ruining, so why should they care.  As the content seller you want to make sure you are paid for content, it cannot be distributed without your approval or knowledge, and that you can instantly revoke access if a charge-back is made against a sale.

The only effective way to prevent misuse by recipients is to apply DRM controls to the PDF books, files or documents you distribute.  And although it may sound a bit Draconian (nice guy, produced codified laws that applied to everybody, downside was the usual penalty was death) it is Digital Rights Management that provides controls.  And for it to be effective you have to interrupt the supposed ‘right’ to make copies of content and pass it on to anyone else – for the purpose of private study or research (as defined by Tom Lehrer of course).

But what must DRM achieve for PDF protection?

DRM means using encrypted files to protect your PDFs (otherwise anyone can copy it), and then preventing other forms of copying.  It includes locking PDF files to registered devices, stopping File Save or Save As (to prevent saving in unprotected format), stopping Select All, CTRL-C and CTRL-V (and mouse right click copy and paste) and stopping the Print Screen key and inhibiting the various screen grabbing programs that even manufacturers provide to make it easier to copy content.  Now that’s a bit to be going on with.  And you might want to put watermarks on the screen so if someone does grab an image it shows your copyright, or their name and email, or both.  This could be important, not because you necessarily want to prosecute people, but because they will feel uncomfortable having their identity linked to piracy.

Also you have to either prevent printing, since a printed PDF book, document, or file can always be scanned, or apply watermarks to the printed copy making it unattractive to try copying.  The arguments are the same as viewed images, except that large scale printing shops have the ability to copy books and double sided prints literally at the touch of a button.  That includes being able to crop headers and footers, so you need to embed watermarks that are within the text, perhaps using super thin fonts so they do not make the text impossible to use.

And when you are selling PDF books, files or documents online there are things that customers expect, that are reasonable to expect of a DRM system.  The system should allow for the PDFs to be transferable to more than one device, either as part of the offer (say – choose any three machines from PC, Mac, iPad, Android) or as a courtesy (extra licenses available).

Another thing that you need to manage is how long the content may be accessed.  For a book this is normally for as long as the book lasts (which is a great deal less than forever, and almost zero time if you get it wet – a bit like a memory stick).  Most commercial content (books, reports, analyses and so on) is bought forever, because that is the model we have always worked on.  Using DRM it is possible to define shorter periods, and there may be essential reasons for that.  Content that is created for the academe (text books for instance) may only be valid for a term or a year and may need to be ceased at the end of that period.  Training courses may only be valid for a specific version of a product, and this is also true of instruction manuals.  Financial information is likely to be time sensitive and the seller may wish to be able to revoke access to old content.  Be aware of the ‘Exhaustion of rights (first sale)’ doctrine that says once you have sold a work, the purchaser has the right to do what they like with their copy, so you may wish to look at the license terms that you use to make it clear it is for a limited period of time and is a personal license for that limited right.

Going back to watermarks for a moment, they do offer a content seller another very important feature that may be rather easily ignored – proof of content.  You will read that a digital signature does this, but not on print out.  Digital signatures only detect a change in a digital file.

This may sound like no big deal.  But for many authorities, their credibility is bound to the proof of their content – an analyst’s report needs to be provably genuine, a certificate or similar credential must not be altered, and so on.  Watermarks have traditionally been used to prevent/detect forgery and alteration, and are just as important now when content that is being sold must be authenticated, although these are printed and not embossed.  The presence of the watermark, unaltered, is the proof that the content is also unaltered.  That means being able to provide your own choice of watermark to suit the content you are protecting.  Good patterns are Mandelbrot images because those patterns do not repeat, or Moiré fringe patterns.  Examples of both may be found on the Internet.  They need to be fine enough that if they are copied they will fade if the contrast is set too high.

So when you select your DRM, make sure it can deliver on protecting your income stream when selling PDF books, documents, and files online.