New iPods block alternative software (briefly)

Stephen Withers
Tuesday, 18 September 2007 10:27

Business IT - Technology

Apple quietly introduced a change to its latest iPods in an apparent attempt to prevent non-Apple software being used with the popular music and video players, but independent developers soon cracked the secret.

The iPod nano, iPod classic and iPod touch all use a hash - the result of applying a mathematical process to data - to ensure that the iTunesDB file was written by iTunes. iTunesDB stores records of the songs and playlists stored on the iPod, in order to obfuscate the location of particular songs.

But a team of programmers keen to keep using the iPod with Linux-based software have figured out the secret values used to compute the hash, and have revealed a method for repairing it after another application has changed the iTunesDB file.

According to the iPodMinusiTunes blog, the hash is "a cryptographic signature combining data from the iTunesDB and a device specific identifier (called the firewireid) and some (formerly) secret numbers."

The code could be reused by developers of audio software such as gtkpod or Winamp to preserve compatibility with the new iPods.

In related news, Apple has issued firmware updates for the iPod nano and iPod Classic released earlier this month, without giving any indication of their purpose beyond bug fixes. The updates may be installed via iTunes.