m4a)” href=”http://www.hymn-project.org/”>hymn — decrypt iTunes and iPod music / unprotect AAC files
    (m4p –> m4a)
To decrypt your iTunes protected AAC files so that they  can be played on operating systems for which no official version  of iTunes exists, such as Linux.
To use non-Apple AAC-capable hardware to play your music.
To eliminate the five computer limit imposed  by iTunes.
To make archival backups of your music.
As the first step in converting your music  from protected AAC to MP3, Ogg, or your other favorite audio file  format, for use with your non-iPod portable audio player.
To demonstrate your belief in the principles  of fair-use under copyright law.