Re: FYI: DRM is Evil. Very, Very, Very Evil
@enes: files received, thanks! I wish I'd checked my PMs sooner; I already had them, but through Mega, which on any browser besides Chrome requires Adobe bloody Flash to obtain. Ugh! Ended up using Chrome on XP, which supports the APIs required. Wasn't going to install it on my Mac. Your download links would've helped me avoid all that.
And thanks to everybody else who got in touch to help me find Inaudible. I will explain in detail the DRM at the end of the post, so people living in restricted countries can tune out and avoid the thought police, but you all played your part in helping me understand how it worked.
My brother got his account back. For whatever reason, his pleading with Amazon got his account reopened. Maybe it was that he mentioned that he was blind. The memo went all the way up to the head of sales in the UK, which might have meant that the RNIB got involved after all. Whatever the reason, he can now log in to his account, make and retur n purchases and access his Audible content on any device once again. Cheers all round. Well, except for the disappointment that is DRM, of course. I'll never be grateful for that. We've all learned an important lesson. As soon as my brother gets the gumption together, and now that he has the time, I'm going to help him download all his books and strip out the DRM. That way this can't happen to him again.
For myself, I have already completely stripped the DRM from my Audible books collection, with no loss of quality whatsoever, and maintaining the original format and encoding. I was too late to return my Audible credits, but I would have, if I could have; Amazon didn't notify me, in December, when the renewal happened, and you only get 14 days to cancel your membership. Dirty trick, that. Still, with these credits on hand, I might as well stock up on books that I've already paid for. The removal of the DRM means, quite simply, that Audible has a gr eat deal more value to me than it otherwise would have. I can buy timeless books I will actually value for eternity because they don't have DRM to make them rot, I can get access to Audible exclusives, and I can use my USB MP3 player to play the books in the other room, which ironically probably means I'll have more time for listening. Naturally, though, I don't reward bad behaviour when I can possibly help it, so I'm going to try and avoid them for new purchases, just as I promised to. These bastards can only hurt people because we let them, so I'm going to try the various alternatives that have been suggested, particularly Downpour. Oh, and no, piracy isn't an option I'm happy with, no matter the provocation; at best it's something to be resorted to if there are no other options for obtaining the content and there is a specific, compelling reason to have it.
Now, what follows is a discussion of the DRM itself. If you're living in an uncivilised nation where corporations write the rules (i.e. the US), then you can stop reading now and avoid a visit from the thought police.
The tool of choice is called Inaudible. It is somewhat hard to find, but happily, the news is spreading, if you know where to look, and as always, especially among Open Sourcerers who don't mind getting their hands dirty. It can perform lossless decryption of Audible book files. The latest format, Audible Enhanced (file extension .aax) is an MPEG4 container with chapter markings in the metadata atoms, encrypted with a per-subscriber key. On Windows, Inaudible is pretty much a point-and-click affair, and can be automated entirely. On OS X, Inaudible includes the tools required, but not the shell scripting knowledge to do bulk conversions, and its UI seems to be limited specifically to converting one book at a time, although it is still useful for discovering keys and testing the tools.
The basic idea of breaking the DRM is f irst to find your four-byte "Activation secret" and then to convert the audible file into a regular MPEG4 container using that secret. The secret is the golden key with which your files are encrypted for all of a subscriber's files. There are three ways to find it: from your existing player, from Audible's own activation server, and by brute-force. Inaudible seems to be using the third method, and has rainbow tables with precomputed keys and a custom implementation for the Audible algorithm for the open-source rcrack tool. It seems to work well, even without access to iTunes or Audible Manager, as was apparently required in the past. I suppose we should be glad that DRM purveyors are stupid as well as malicious; the key is 64 bits and is usually found in seconds. However, for a fully networked solution, there is the "Audible activator" from the same open-source inaudible-ng project--basically a tool for sending the username and password query to Audible 's server for activation, just as your client would.
Now you have your secret, store it away in a safe place. This is your ultimate weapon, together with your Audible files, if you should get disconnected from Audible. Next comes the actual decryption process. This part I learned from the Mac Inaudible tool: ffmpeg is, as it is so often, your friend. Ffmpeg is a well-known general-purpose audio/video manipulation tool. The Audible format is essentially encrypted MPEG4 with AAC data and metadata atoms, and ffmpeg has support for it, specifically. Using a command like
ffmpeg -activation_bytes 00112233 -i input.aax -codec:a copy -sn -vn output.m4awill get you a decrypted Audible file, with the original AAC audio data untouched and all metadata, including chapter markings, ported across to the new, unencrypted container. There is no transcoding of any sort involved, so the process is very quick, even for 32 GB of files, as was my case. If you were to rename a decrypted file to have a .m4b extension, you would find that, imported into iTunes, it would work exactly like the real deal--it simply won't have the DRM anymore. The -vn and -sn switches drop video and subtitles, respectively; this includes cover art. Now you just have to figure out how to do this for multiple files, including those with spaces and other shell characters in their filenames, and you can process your entire collection. This is left as an exercise for the reader, but I used the find command to great effect here.
I hope this helps the poor souls out there with Audible content they wish to liberate. I can tell you now that it's made me very happy, because it is so perfect and flawless, and produces files that are actually indistinguishable from the originals. I'm very grateful to the awesome people who reverse-engineered the format and turned what has long been a pillar of despair involving crusty old versions of Windows software producing huge files that are poorly re-encoded, into a simple, one-step process for producing files as they were meant to be, without loss of quality, with chapter markings, that can be converted however I wish if need be. It really is awesome to experience Audible without the DRM; it's just Audible, only better.
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