The only files encrypted in RFB&D books are some of the html and smil
files. The mp3 files themselves are not encrypted as you can easily see by
playing them in any player such as winamp. The files have random names which
prevents users from making playlists or whatever to play them in the proper
order. This effectively prevents unauthorized users from using the book
since many books have over a hundred mp3 files. So it would seem to me there
could be a way to transfer the mp3 files to each bookport since they are the
same for a given book and then transfering the files that need decryption
separately. Html and smil files are small compared to the mp3 files making
up a book. I hope APH seriously considers offline processing. Parameters for
your bookport could be store and any required encryption could be done
without the unit wasting batteries.