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Share a script/alias you use a lot
(lemmy.blahaj.zone)
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this post was submitted on 23 Jun 2025
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I use Clevis to auto-unlock my encrypted root partition with my TPM; this means when my boot partition is updated (E.G a kernel update), I have to update the PCR register values in my TPM. I do it with my little script
/usr/bin/update_pcr:I run it with sudo and this handles it for me. The only issue is I can't regenerate the binding immediately after the update; I have to reboot, manually enter my password to decrypt the drive, and then do it.
Now, if I were really fancy and could get it to correctly update the TPM binding immediately after the update, I would have something like an apt package shim with a hook that does it seamlessly. Honestly, I'm surprised that distributions haven't developed robust support for this; the technology is clearly available (I'm using it), but no one seems to have made a user-friendly way for the common user to have TPM encryption in the installer.
Is clevis using an attestation server or is it all on a single machine? I’m interested in getting this set up but the noted lack of batteries included for this in the common distros makes it a somewhat tall order.
In my case, no; it’s all a single machine - it is in the initramfs and uses the system’s TPM to (relatively) securely store the keys.
It can be set up with an attestation server, but you certainly don’t have to do it. The Arch wiki has a really good article on getting it set up.
How difficult is it for an adversary to get in the middle of the TPM releasing the keys to LUKS? That’s why I would want attestation of some sort, but that makes it more complicated and thinking about how that would work in practice makes my head spin…
Vulnerabilities certainly do exist, but I’m pretty sure the attacker has to be well-equipped
I’d call it a protection against data getting cracked in a petty theft, but if your attack vector is much more than that, there are other measures you should probably take. I think Clevis also works with Yubikeys and similar, meaning the system won’t decrypt without it plugged in.
Heck, I think I know someone who just keeps their boot partition with the keys on it on a flash drive and hide it on their person.