Jon develops new utility to decrypt iTunes DRM tracks

April 6, 2004

Back in November, DVD Jon Lech Johansen who originally helped distribute the DVD DeCSS had developed a utility to dump a QuickTime stream to a file. Now he has written
code under the project
name 'playfair' to allow iTunes users to decrypt their purchased AAC files. The utility works by taking the decryption key from either an iPod (required for MAC users) or iTunes for Windows (no iPod required) and using it to decrypt the DRM protected AAC track into a regular AAC file.

However this utility will not work if you do not have the key to the protected song, for example if you copied the DRM protected iTunes tracks off another machine. The utility will optionally also copy the tags (artist, name, etc.) and cover art into the output AAC file. The resulting decrypted AAC file may be used as with any other AAC file including the use of other AAC compatible players or transferred to another computer.

Jon Lech Johansen's code that circumvents iTunes DRM has been given a fresh workout. A project named 'playfair' allows users with an iTunes key to create unencrypted AAC files. Apple uses the AAC format in combination with FairPlay DRM to lock down the music bought from its iTunes Music Store.

"The playfair program is quite simple," according to the README. "It takes one of the iTMS Protected AAC Audio Files, decodes it using a key obtained from your iPod or Microsoft Windows system and then writes the new, decoded version to disk as a regular AAC Audio File. It then optionally copies the metadata tags that describe the song, including the cover art, to the new file."

The restriction doesn't allow wholesale decryption: you must own a key and the files must be associated with that key. On the Macintosh, you'll also need an iPod to generate the key.

Jon Johansen first published his circumvent ion in November, and in January worked it into the open source VideoLAN project.

Despite Steve Jobs comments to Rolling Stone magazine - "we don't believe it's possible to protect digital content" - Apple continues to lead the industry in attempting protecting digital content. It promises to keep the hackers busy: a patent application published last July indicates that Apple is brewing its own DRM, which it may or may not share with the industry. The author co-chaired the secretive Copy Protection Technology Working Group - which bars journalists from attending its sessions - with representatives from Sony Corporation and Warner Brothers.

While Apple may not be happy with its iTunes DRM being hacked, they may run into another problem: Apple rely on hardware sales to make profit, but as this utility can convert purchased tracks into standard AAC files, it gives the end user the ability to use any AAC compatible player to play their purchased iTunes music.

Source: The Register