I know this is in good-natured jest, but wouldn’t the arrival of widespread quantum computing, which need to be absolutely decoupled from their environment so as to prevent decoherence, actually be an enormous step forward in almost all these “side channel” attacks? In the sense that decoupling must by definition limit any exchange of information that might constitute ‘observation’, and as such, the goings-on of a quantum computer become literally unobservable on the pain of nonfunction.
Current quantum computers don't have much in the way of microarchitecture. No caches or branch prediction obviously.
But if you were timesharing on a quantum machine (which, given that they need $1M microkelvin coolers seems like it will be common) it's not impossible that information could leak. Given the analog way they work, you could probably set up a computation that would be sufficiently sensitive to initial conditions that the not-entirely-decayed-to-zero previous computation could influence it.
Uhm... no, I think not: to get information out of the quantum computer as output for the ”previous user” it needs to go through an explicit phase of observation, busting all the state (?), and loading up new data for the subsequent user’s computation also constitutes ’observation’ since there’s knowledge of the inner state of the quantum system outside the strict confines of the quantum system. I really don’t think you could at any moment in time get information out of a side-channel, otherwise the thing wouldn’t compute.
(Yup, of course they’re extremely simplistic in terms of inner architecture, but that’s quite beside the point, as I think we both agree.)
It's true that the quantum state can only be observed once, but at the end of the observation the resolved state exists classically in the phase of the resonating elements. Also, the input vector continues to be there. Leaking either is a leak.
Nah, that wouldn't work - simple CPUs, by virtue of going slower, being less complicated inside and using more power per cycle, would be easier to snoop at through EM channels.
And then, they discovered that by putting the 8-bit machines under metal rollers moving 12-foot-wide plastic film at 10 meters per second, their signals could not push through the resulting force field.
