Even then - the manufacturer could supply design documents that surreptitiously include backdoors... there's simply so much to look at when it comes to actual c

Even then - the manufacturer could supply design documents that surreptitiously include backdoors... there's simply so much to look at when it comes to actual circuit schematics, I can't see how anyone would spot "backdoor" circuitry amongst everything else that is presumably legitimate. I don't know much about silicon, so maybe I'm wrong.