[ucc] Vending machine authentication ideas?

[Bernard Blackham]

On Wed, Jun 23, 2004 at 10:18:20AM +0800, Davyd Madeley wrote:
> On Wed, 2004-06-23 at 03:23 +0800, Bernard Blackham wrote:
> > So we've finally got the vending machine completely controllable via
> > a serial port. We've also got loads of room to spare on the ROM.
> > What would be very nice is to be able to implement some sort of
> > authenication or integrity checking on the serial protocol, so that
> > a random passer-by can't simply unplug the vending machine, plug his
> > own machine in and start dispensing away.
> 
> > Can anybody suggest something suitable?
> 
> Excellent. And when we loose the snack machine password? How does one
> root a snack machine? I suppose you would make it rootable over the
> serial interface, but doesn't that defeat the purpose?

Yeah, you reset it by flipping a DIP switch in the machine and this
allows you to change the password. ie, you need to be able to open
the machine.

> That dip switch should be well documented inside the machine.

Documentation is in the ROM on the serial port with the 'HELP'
command. You can check out the rom from CVS on mussel and run "make
sim" to get a simulated version with any luck. It won't simulate IO,
but it'll show you the idea of the interface.

> Make sure that many commands can be run without "enabling".

Already done.

Bernard.

-- 
 Bernard Blackham <bernard at blackham dot com dot au>