What mode of operation of AES was used for the analysis?

ECB, I think? The focus was definitely on attacking the crypto core per se.

(Of course, ECB is almost certainly a bad idea if you're trying to build an actual application!)

Yes, ECB, although other modes would only require superficial changes. In practice the harder task is actually identifying the mode in use!

Doesn't the device case act as a faraday cage?

Less so than we expected; a metallic case definitely reduces the signal strength, but IIRC for the one case we tried placing, the small-loop antenna directly on the case still gets you a good-enough signal to break this (pretty basic) AES implementation. Someone could definitely do more research into that, though - we only did a one-off experiment.

Of course, everyone uses plastic nowadays... ;-)

> but IIRC for the one case we tried placing, the small-loop antenna directly on the case still gets you a good-enough signal

Was the case grounded?

Laptops are mostly plastic and some non-grounded metal. Desktops are mostly grounded steel.

Steel may be permeable enough for a tempest attack. I don't know.

Good point. The case wasn't grounded but that is more common for embedded targets/laptops.

We haven't looked at attacking desktops but the fact that there is a market for tempest shielded desktops (from OSPL, etc.) is perhaps an indication that it might still be possible...