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Pottermore DRM is Hacked – Provided by Booxtream

It never takes long for DRM to be identified and cracked, and the Harry Potter ebooks sold by Pottermore are no exception. It took a couple hours of disassembling the Epub and going over it line by line, but it’s pretty clear that the digital watermarks, a benign form of social DRM, are being provided by Booxtream, a several year old Dutch tech company.

When Pottermore was announced last summer, one of its big selling points was the ebookstore where you’d find DRM-free ebooks. That promise turned out to be not completely true, but the Epubs you buy there are free of what you would expect to find in most ebookstores.

Instead they come with something called a digital watermark. These watermarks effectively are little bits of data buried inside the ebook. It’s a benign form of DRM that doesn’t bother the average user. Unlike other forms of DRM, a unique digital watermark is created when each copy of an ebook is generated. This lets the ebookstore add something to the ebook which can still be to track down who originally bought (and then pirated) a particular copy of an ebook.

Similar tech has been used for some time now in music, documents, and other content, but Pottermore is the first high profile ebookstore to use it (that we know of).

In the case of Pottermore, the digital watermarks are almost certainly provided by Booxtream. has taken apart an Epub and identified the particular details as being the work of that Dutch firm. I also looked into this, and my findings match theirs.

In case you’re interested, the digital watermarks use by Pottermore are serial numbers added to various files. There’s a warning statement on the copyright page, but the true watermarks are slightly better hidden. You can find them as strings of text in the title element of some of the images. Also, identified an element in the CSS file as being from Booxtream. I believe they’re referring to "boekstaaf". That’s the only element that is clearly not based in English. I believe it’s a Dutch name, which for obvious reasons would likely have come from a Dutch company.

Update: I’m pretty sure the file names are also used as a digital watermark. I just got my hands on a second copy of HP1 and the internal files have different names.

Booxtream has been supporting a Dutch ebookstore for the past 18 months or so, and so far as we know Pottermore is the first major use of their technology. Let’s hope it’s not the last. Let’s also hope they also added a more subtle digital watermark; the one I found is far too easy to remove.


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TheSFReader March 28, 2012 um 11:43 am

Why too easy ? Easy is not really bad. Regardless of the difficulty, it’ll be broken. If it educates users it’s allright!

Mike Cane March 28, 2012 um 12:17 pm

Hmph. So some of it was in the CSS too, as I suspected.

George March 28, 2012 um 1:36 pm

It’s hardly hacked is it? I believe it’s called "booxtream" though, minus the s. At least, I figured this from the incorrect url (google suggested

Sweetpea March 28, 2012 um 3:18 pm

No matter how difficult the DRM is, it will be hacked. But if the DRM is there, but not bothersome, the average user doesn’t feel the need to hack it. Only the pirate will hack it to distribute. And they will succeed whatever you do. Even printing on paper won’t stop them…

Zetmolm March 28, 2012 um 4:31 pm

Of course social DRM is a lot better than the traditional form of DRM, but any investment in it is a waste of money for the publisher. All they are buying is a false feeling of comfort. No matter how subtle they make it, you can get rid of this type of DRM simply by converting the book to txt format. Anyone can do that e.g. using Calibre, no special tools are needed. (OK, you loose the formatting, but Harry Potter and a lot of other fiction is all about the text of the book.)

SBT March 30, 2012 um 5:13 am

Actually, it’s quite feasible to watermark pure text. You can for example add extraneous spaces ( s) to the end of paragraphs. Still simple to remove, of course, but you must as always know what you are looking for.
And that is the crux of watermarks. It will presumably have multiple layers, some obvious, some not. Good watermarking ensures you will never be 100% sure you’ve removed it all.

Logan Kennelly March 28, 2012 um 5:37 pm

Ugh, you guys are using the term DRM only to drive traffic … and it worked because I’m here.

"Social DRM" is a term cooked up to make watermarking an easier sell to people that insist on "DRM". Does my money have DRM to crack because it includes a watermark? Does an iPod have DRM because it has the user’s name on the about screen? Does my car include DRM because of the etched VIN? I proclaim that they do not.

So let’s get past that nonsense … is there anything hostile toward the customer about watermarking? I can still use the product in any way I wish, including, as Zetmolm points out, converting to another format that will almost certainly strip the marking. The fight should be for consumer rights, and these systems do not inhibit any that I can see.

If these systems included a per-unit cost that drives up the end price of the book, then you have a valid argument. But if the retailer wishes to add "this book originally purchased by Maurice Sendak" to the title page and it doesn’t cost a penny, then where has the retailer gone wrong?

Nate Hoffelder March 28, 2012 um 5:53 pm

Adding watermarks does add cost, yes. The software on Pottermore’s servers cost money to develop and it costs money to run it each time you download an ebook.

And no, I used the word DRM in the title because I couldn’t think of one that would fit as well. Also, I know people who would insist that it is DRM.

fjtorres March 28, 2012 um 7:43 pm

DRM= Digital Right Management. It is *not* the same thing as encryption, though encryption is part of many DRM systems.
Watermarking is also *part* of many DRM systems. Commercial audio and video files are routinely watermarked to identify illegal uploaders.

Tyler March 28, 2012 um 8:14 pm

I bet that the Harry Potter books would cost the same with the watermarking DRM or with Adobe DRM or without the DRM.

Tom March 29, 2012 um 3:08 am

I’m Dutch… I can confirm that "boekstaaf" is a Dutch word, meaning "bookmark"

Nate Hoffelder March 29, 2012 um 9:54 am

It’s also showing up as a lot of people’s last name, which is why I didn’t put it through a translator.

Tom March 29, 2012 um 10:36 am

well Nate, I was wrong… it doesn’t mean "bookmark" exactly.
It’s a conjugation of the verb "boekstaven", which means "to record or to chronicle".
So maybe it is some kind of record in CSS or XML?
I’m not very fluent in either, so I don’t know.

Pottermore eBooks Already Showing up on Torrents – The Digital Reader March 29, 2012 um 2:58 pm

[…] statement from the copyright page. He didn’t do anything to remove the digital watermarks I reported on yesterday.And BTW, now that I have a second copy of HP1, I can see that the files inside that Epub have […]

Steve July 14, 2012 um 5:00 pm

I thought Pottersmore does not have DRM, but only watermarking.
Watermarking technologies now seem to be evolving – there is one that tracks ebook usage –

e-Lire – Gestion Magique des Droits pour les EBooks (Magic Rights Management) June 27, 2013 um 4:28 pm

[…] sont « tamponnées » numériquement dans le livre. D’après The Digital Reader, Pottermore utilise le marquage de Booxtream, et j’ai évalué cette technologie moi-même […]

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