Turns out the signature files are something that allows the firmware to be loaded onto the device. So scratch off ARCHOS and their fucking proprietary secrets. They may be technically in compliance with the GPL but they won't get my business.
Now I'm looking at the Nokia 770. There are some going on eBay for around $100 each.
last updated 2013-01-10 20:54:27. served from tektonic.jcomeau.com