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...