Earlier quoted context omitted.
> For us, the benefits of TPMs and measured boot for personal use are a lot more obscure. You'll sometimes hear people claim it protects against 'evil maid attacks' where an attacker repeatedly gets physical access to your laptop. The truth is it provides no such protection. TPMs give you fine and adequate protections in many scenarios, even physical ones. They also provide you with better protection for private key…
> TPMs give you fine and adequate protections in many scenarios [...] my `ssh-tpm-agent` project I agree that's adequate, in the sense that keeping the an SSH key as a password-protected file on disk is adequate, and having it be a password-protected secret in the TPM is no less secure than that. But the whole point of binding a key to hardware is to be secure even if a remote attacker has gotten root on your machine…
It protects against extraction, not usage on the machine itself. Of course they can use the secret on the compromised machine.
> And although that's a bit limiting, once they've SSHed to a host as me once they can add their own key to authorized_keys in many cases.
Assuming they can edit the file.
> That's why Yubikeys and U2F keys and suchlike have a physical button.
The TPM spec has a policy setup to account for some fingerprint reader that can be used to authenticate. I haven't been able to figure out how/what/whys of the implementation here but this is very much a thing.