But wouldn't a properly configured LUKS encryption protect against nation-state threats too? If so, then why still use TPM?
There's more applications of trusted computing and TPMs than that; one of them is using it to safeguard your own keys.
I think you misread the GP. Your definition of DRM is exactly what GP described as his use of the TPM.
>>I sell a device. There are lots of them in hands. You still aren’t getting my device key off of it. Yes, you can use that device all you like, but you aren’t going to clone it and make more.
What the GP describes is not safeguarding the nominal owner of the devices' keys. GP is restricting the nominal owner of the device on behalf of himself as the manufacturer. This is leveraging the TPM for DRM.
Other possible less nefarious uses of the TPM are irrelevant to this point.
Or something else! Payment cards work like that – they hold keys that nobody is supposed to be able to duplicate; certainly not third-parties, but also not the legitimate account-/cardholder.
There are plenty of uses for trusted computing other than DRM; they're just usually not as disruptive/frustrating to legitimate customers as DRM (and as a result are not as contentious), so they don't get as much attention.
TPMs jeopardize the ownership of a device. Consumer devices are already sold where you can't (easily) inspect or change anything.
Even a user-controlled TPM can be used as storage for keys used to usurp control of the device. The existence of IME and PSP enables manufacturers to have more control over computing devices than the people who buy and operate them.
There is no moral defense for sabotaging ownership.
That’s all very well until you start talking about hardware that does things like providing video of the inside of someone’s home. I’m still behind being able to modify them and use them as you please, but if you do so that should be self-evident, because otherwise *someone else* can do so, and you won’t know until video appears on the internet if you walking back from the shower.
TPMs don’t necessarily mean that you can’t modify a device you’ve bought, it just means that things like the API key which connected it to the backend will be invalidated and you’ll have to set the device up some other way. That’s a safety mechanism, and even I want it to be present in hardware I buy.
Likewise I don’t want someone to be able to take a doorbell from the front of my house, extract my wifi credentials from it, and pivot from that to compromising the entire network.
I’m sure some people will say “well just don’t have those things”, and I’m inclined to agree, despite having worked on such devices I’m not sure they’re actually hugely useful to most people. People are buying them though, they’re in the wild, let’s make them as secure as possible.
> No, DRM is safeguarding other people's keys on your device.
Correct - in this case, safeguarding mainly means making sure that the nominal owner of the device does not extract the keys.
> There's more applications of trusted computing and TPMs than that
Correct
> one of them is using it to safeguard your own keys.
Questionable - needs a definition of safeguarding. Making sure that the keys cannot be backed up would be a strange definition.
It's all trade-offs.
The separate authentication server can be configured to only hand out the storage encryption key on expected reboots, so if the machine unexpectedly walks off and then powers back on that server would refuse to hand out the key, thus the stolen machine is now useless.
Try it on a secure boot and tpm2 enabled Bitlocker encrypted drive, the only way to get in is via the recovery key after a configurable number of attempts.
For example I know that the police in my country use off the shelf disk cloning devices and then some basic forensics software for analyzing the disk image. This can be done by an average computer technician, and such a TPM scheme would totally prevent them from extracting data. Of course for bigger cases they can invest some more effort, but they would have to be sure that there is some important data there to justify the cost.