>And if the hardware itself has microcode that overrides your code?
Hard to defend against this, but it can be helped by using well understood architectures and letting us confirm that the microcode being run is the same microcode that the upstream CPU vendors are publishing.
>Actually, I think the first and foremest threat would be, "Could someone insert a yubikey into a malicious device that changed its behavior such that it now leaks information and does not provide actual security."
I'm not going to keep entertaining this discussion if you keep disregarding everything I've already said. I've already said I'm only asking for read-only access. In any case, defending against physical compromise is close to impossible anyway.
Hard to defend against this, but it can be helped by using well understood architectures and letting us confirm that the microcode being run is the same microcode that the upstream CPU vendors are publishing.
>Actually, I think the first and foremest threat would be, "Could someone insert a yubikey into a malicious device that changed its behavior such that it now leaks information and does not provide actual security."
I'm not going to keep entertaining this discussion if you keep disregarding everything I've already said. I've already said I'm only asking for read-only access. In any case, defending against physical compromise is close to impossible anyway.