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> Well, it is an air gapped system that depends on a possibly insecure input and output device. No, an air gap means that there is a gap of air between the sys

> Well, it is an air gapped system that depends on a possibly insecure input and output device. No, an air gap means that there is a gap of air between the system and any insecure network. By definition, a YubiKey plugged into a networked laptop is not airgapped because there is a direct electrical connexion to the laptop’s USB controller, which has either an electrical or an RF connexion to one or more networks. > Every air gapped system has the weakness that you have to eventually get material on and off the system. I really think that you misunderstand what an air-gapped system is. A desktop not connected to a network is an air-gapped system, and can be very useful. For years we computer enthusiasts used non-networked — air-gapped — computers and loved them. An air-gapped desktop publishing system would be very useful for producing samizdat in a repressive regime, for example. I imagine folks did exactly that in the late 80s in the Soviet Union. In my youth, all video game consoles were air-gapped, and they were very useful.

tialaramex 5y ago
Right but, did you spot that in your answer you allowed for a situation where there isn't actually that gap of air at all, just because it felt intuitively reasonable to do so? There is no "air gap" in your sense between say a Sega Megadrive and Google's servers, they're both wired to the electrical grid. But you (not unreasonably) disregard that. In contrast there is technically such a gap between my laptop and Google's servers, because it's running on a battery - however thanks to WiFi it certainly isn't "air-gapped" in the sense we usually mean. Security Keys are indeed often electrically connected (via a USB port) but the design insulates this from the key management problem so in effect they are air-gapped. Any attack that crosses that gap might equally have worked by shining a laser at it through a window, or holding an electromagnet near it.

tialaramex 5y ago

Right but, did you spot that in your answer you allowed for a situation where there isn't actually that gap of air at all, just because it felt intuitively reasonable to do so? There is no "air gap" in your sense between say a Sega Megadrive and Google's servers, they're both wired to the electrical grid. But you (not unreasonably) disregard that. In contrast there is technically such a gap between my laptop and Google's servers, because it's running on a battery - however thanks to WiFi it certainly isn't "air-gapped" in the sense we usually mean. Security Keys are indeed often electrically connected (via a USB port) but the design insulates this from the key management problem so in effect they are air-gapped. Any attack that crosses that gap might equally have worked by shining a laser at it through a window, or holding an electromagnet near it.