From: Cathal Garvey <cathalgarvey@cathalgarvey.me>
Without getting into the issue of whether patents encourage innovation.. I do think that medical devices are a special case. If you have a heart implant, that thing needs to be "unhackable", but also totally verifiably safe. So there should be firmware signing, no mutable state, verifiable memory safety...but the code should be open source, and if need be the firmware signing key for each device (needs to be different for each device!) should be accessible by a legitimate owner.
So, no more remote-hackable heart implants, but doctors and cardiac technicians can still apply critical patches and inspect the source for sanity.
It should be fairly simple to protect against heart-implant hacks. First, communication with them is probably limited to inductively-coupled signalling, at a fairly high level. Secondly, it should be based on a two-way challenge/response system: The external device signals a code, call it a password, to which the implant would respond with a reply, which itself includes a randomized code. The external device reads that randomized code, processes it in some way (presumably a hash), and retransmits it to the implant. Only if the implanted device receives what it considers the correct code, would it allow further manipulation. Presumably, any attempt to illegitimately access such a device wouldn't be close enough to read the implant's reply signals, and thus couldn't proceed further. "Do you have have a match?". "No, but I have a lighter". "Even better". "Until they go wrong". Jim Bell