by cyphar | 2026-01-29 11:57:53+00:00
I'm really not trying to be slick, but I think it's quite difficult to convince people about anything concrete (such as precisely how this model is fundamentally different to models such as the Secure Boot PKI scheme and thus will not provide a mechanism to allow a non-owner of a device to restrict what runs on your machine) without providing a concrete implementation and design documents to back up what I'm saying. People are rightfully skeptical about this stuff, so any kind of explanation needs to be very thorough.

As an aside, it is a bit amusing to me that an initial announcement about a new company working on Linux systems caused the vast majority of people to discuss the impact on personal computers (and games!) rather than servers. I guess we finally have arrived at the fabled "Year of the Linux Desktop" in 2026, though this isn't quite how I expected to find out.

> Attestation of what to whom for which purpose? Which freedom does it allow users to control their keys, how does it square with remote attestation and the wishes of enterprise users?

We do have answers for these questions, and a lot of the necessary components exist already (lots of FOSS people have been working on problems in this space for a while). The problem is that there is still the missing ~20% (not an actual estimate) we are building now, and the whole story doesn't make sense without it. I don't like it when people announce vapourware, so I'm really just trying to not contribute to that problem by describing a system that is not yet fully built, though I do understand that it comes off as being evasive. It will be much easier to discuss all of this once we start releasing things, and I think that very theoretical technical discussions can often be quite unproductive.

In general, I will say that there a lot of unfortunate misunderstandings about TPMs that lead people to assume their only use is as a mechanism for restricting users. This is really not the case, TPMs by themselves are actually more akin to very limited HSMs with a handful of features that can (cooperatively with firmware and operating systems) be used to attest to some aspects of the system state. They are also fundamentally under the users' control, completely unlike the PKI scheme used by Secure Boot and similar systems. In fact, TPMs are really not a useful mechanism for protecting against someone with physical access to the machine -- they have to trust that the hashes they are given to extend into PCRs are legitimate and on most systems the data is even provided over an insecure data line. This is why the security of locked down systems like Xbox One[1] don't really depend on them directly and don't use them at all in the way that they are used on consumer hardware. They are only really useful at protecting against third-party software-based attacks, which is something users actually want!

All of the comments about DRM obviously come from very legitimate concerns about user freedoms, but my views on this are a little too long to fit in a HN comment -- in short, I think that technological measures cannot fix a social problem and the history of DRM schemes shows that the absence of technological measures cannot prevent a social problem from forming either. It's also not as if TPMs haven't been around for decades at this point.

[1]: https://www.youtube.com/watch?v=U7VwtOrwceo