Comment by tapoxi
1 day ago
This is called the Endorsement Key, and you're correct, it never leaves the TPM. The TPM is a "black box" to the OS.
1 day ago
This is called the Endorsement Key, and you're correct, it never leaves the TPM. The TPM is a "black box" to the OS.
Ah, got it. With enough motivation this is still pretty easily defeated though. The key is in some kind of NVRAM, which can be read with specialized equipment, and once it's out, you can use it to spoof signatures on a different machine and cheat as usual. The TPM implementations of a lot of consumer hardware is also rather questionable.
These attestation methods would probably work well enough if you pin a specific key like for a hardened anti-evil-maid setup in a colo, but I doubt it'd work if it trusts a large number of vendor keys by default.
Once it's out you could but EKs are unique and tied to hardware. Using an EK to sign a boot state on hardware that doesn't match is a flag to an anti-cheat tool, and would only ever work for one person.
It also means that if you do get banned for any reason (obvious cheating) they then ban the EK and you need to go source more hardware.
It's not perfect but it raises the bar significantly for cheaters to the point that they don't bother.
> Using an EK to sign a boot state on hardware that doesn't match is a flag to an anti-cheat tool
The idea is you implement a fake driver to sign whatever message you want and totally faking your hardware list too. As long as they are relatively similar models I doubt there's a good way to tell.
Yeah, I think there are much easier ways to cheat at this point, like robotics/special hardware, so it probably does raise the bar.
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