[SDW] Rendering Untrusted Documents in Dedicated Hardware (Qubes Air)

[deeplow]

Why?

Part of the long-term vision of Qubes is to support remote machines as well a virtual ones. They call this "Qubes Air" in the original 2018 article introducing it. But while the Qubes team (and therefore, downstream projects like SecureDrop Workstation) are on top of Xen security patches, they are a non-negligible number, as Joanna Rutkowska highlighted:

Since the beginning, we’ve relied on virtualization technology to isolate individual qubes from one another. However, this has led to the problem of over-dependence on the hypervisor. In recent years, as more and more top notch researchers have begun scrutinizing Xen, a number of security bugs have been discovered. While many of them did not affect the security of Qubes OS, there were still too many that did. :(

We're still in early stages of Qubes Air, but it may become a practical possibility over the next few years, so we should consider what it offers, particularly, for the most untrusted operation -- opening documents. With it, a user would be able to view documents as they do today, but without the risks of hardware virtualization.

How?

The practical details are still up in the air (pun intended), here's a list of things we'd need:

• Amnesiac hardware
  • A device (raspberry pi) which could be have it's state reset on demand (for a new document to be processed)
  • No WiFi or other explicit exfiltration methods
  • Qubes tooling installed on OS
• hardware connection (whichever Qubes Air happens to support)

[eloquence]

This opens up some interesting possibilities, but I'd personally advocate prioritizing work on this below getting the Qubes->Dangerzone->Signal pipeline to be really solid, so this seems more a 2026-2027 thing to me. Sanitizing files and then passing them on is IMO the common case, while achieving further security benefits beyond Xen virtualization seems to be something that only a very small percentage of users are likely going to want to rely on.

[deeplow]

Totally. I feel like it's the same thing for Qubes in term of timeline. I don't expect the Qubes Air technical infrastructure to be there before late 2026, and 2027 more realistically.