Plaidophile

One of the (minor but important) parts of the Topaz format is, of course, the DRM, which has so far eluded being compromised, which is funny because it's actually a pretty trivial "secret-sauce" algorithm which was implemented under some pretty ridiculous constraints (I had limited time to implement it, wasn't allowed to pull in any external libraries, and had to keep it performing quickly without using much memory on an already-constrained device), and somehow it's eluded being cracked for a bit over two years.

Until now.

Earlier today, someone (who I will of course keep nameless) asked me about a bit of Python code (which I will of course not link to) that he'd found which ostensibly would strip the DRM from a Topaz file as downloaded by the KindleForPC app. I looked at it, and yes, it looked like a plausible DRM stripper; presumably it was developed by someone who had run a disassembler on KindleForPC. It did require being run on the same PC as the Topaz file was provisioned for, however. But of course, this enterprising experimenter did not stop there: he analyzed the (again, pretty trivial) encryption algorithm and found a weakness in it (one which I will not name, but which I was aware of as a possibility even when I wrote it), and after not too much time, he'd written a C++ program which would very quickly brute-force the underlying encryption key and completely strip the file of all DRM.

He said that he wasn't interested in releasing it himself (he mostly did it as an intellectual challenge), and for obvious reasons I won't be releasing it either (or even describing the nature of the exploit), but yes, Topaz DRM has been completely compromised at least once, and it wouldn't surprise me if someone else has also figured out the flaw in the algorithm.

I just want to say ahead of time (before everyone emails, IMs, etc.) me that I am aware that it's broken (and this is for real, not the many previous iterations of Mobi DRM being cracked that had nothing to do with Topaz) and also state in my defense:

• I am pretty anti-DRM myself. Not that I went out of my way to make the DRM on Topaz fragile per se, but I was under enormous management and time pressures (as I stated above) and only did a minimum-effort job as a short-term solution with the intention of revisiting it later. I'm actually pretty shocked that nobody at Amazon improved the DRM since I left (or even made any changes to the file format at all, as far as I can tell); they didn't even bother to wrap KindleForPC downloads in an extra layer of DRM like they did for Mobi books (which is what the previous "KINDLE DRM CRACKED!!!" announcement was about).
• I was expecting it to be cracked within weeks or months of Kindle's release, but it took over two years. Not bad for something that can be brute-forced in a few milliseconds if you know the secret sauce (and considering the filesystem had been dumped within days and people could have run a disassembler on it, why was the sauce a secret this long? IT IS RUSSIAN DRESSING, PEOPLE).
• The primary weakness in any DRM mechanism is one with key exchange. Even if I had used a stronger encryption algorithm (which would have prevented the brute-force no-key attack, or at least slowed it down significantly), there's still the issue of keeping the device key secure (which is basically impossible).
• Cracking Topaz DRM doesn't really make book piracy any easier. For starters, someone needs to get a copy of (i.e. pay for) the book, and Topaz books tend to be of more niche interest. The ones which are of more widespread interest tend to get pirated in other ways, such as teams of book pirates doing their own plain-text conversion from an actual book, long before the Topaz version even becomes available to begin with.
• It is also a bit of a pain in the ass to put an unencumbered Topaz file onto any arbitrary Kindle-type device (Kindle, PC, iPhone/iPod Touch), and while this helps the various reverse-engineering efforts, the format is still pretty complex.
• The big boon I see for the removal of DRM is purely in the legitimate customer's interest; people want to back up their Topaz books without having to reprovision them in the event that they change devices. Currently they have no legal way to do this, especially if a book gets retracted by the publisher (as in the famous and overly-ironic 1984 case).
• People are fundamentally honest and good. They pirate only when the legal approach is too cumbersome. Witness how the iTunes music store and AmazonMP3 and so on continue to have plenty of sales even with illegally-traded pirated mp3s, which have certainly been more prevalent for much longer (and derived from plain CDs) than those services have been DRM-free.
• There is still a pretty high barrier to people stripping the DRM from their Topaz books; even if someone were to release this app (which neither I nor the curious experimenter are going to do), you still have to do a lot of things to get the actual .tpz/.azw/whatever file off the device and once you have it, you can't really do much with it.

• It has absolutely no relationship to any other ebook format out there; it is not "mobipocket with fonts," it is not "a proprietary implementation of ePub," or any of the other ridiculous things I've seen written about it from people who have no idea but make these statements as if factual
• The defects in Topaz books are because of defects inherent to the conversion process (which are the same defects which lead to it being converted in the way it exists to begin with), and not "piracy traps" or the like
• It was not designed as a "better DRM than Mobipocket." It exists to fill a niche that only Amazon was capable of filling (at the time)
• The nature of the files means that writing a viewer for other platforms is non-trivial; while it's possible to extract plain text from it, the plain text won't be particularly useful or accurate (and the plaintext representation of the book is only a very very small part of the file).
• Topaz was not designed as something "only for the big publishers." Amazon does not provide Topaz tools to third parties. Only Amazon has the conversion tools to create Topaz books.
• Topaz is not "the native format of the Kindle." If anything, I had to fight like crazy to keep it on the device — many, many times various people tried to kill the project because they had absolutely no faith in it or me. It was getting sick of this fight that most directly contributed to me deciding to part ways with Amazon two and a half years ago.
• The format has problems and it's arguably roundabout and circuitous for getting a worse result than a more obvious approach, but it has very good reasons to exist. If the books that are in Topaz format weren't in Topaz format, they wouldn't be in any legal ebook format. The point of Topaz was to prove to an old and established industry that ebooks are beneficial, and provide them an easy means to make it happen so that in the long term, everything will be available as a well-formatted ebook to begin with.