[1] https://blog.invisiblethings.org/
[2] https://blog.invisiblethings.org/papers/2015/state_harmful.p...
[3] https://blog.invisiblethings.org/papers/2015/x86_harmful.pdf
Seems like she'd have more effect designing hardware.
A: Stinkier without, therefore Qubes.
I'd consider betting on one of those things being solid on its own, but not all of them together.
If you've spent any time with Intel's phone-book-sized opcode manual, or following the history of the PC, you get real skeptical when the words "secure" and "PC" are mentioned together.
In my own space, the approach has typically been to minimize attack surface by using the least amount of the simplest possible hardware we can get away with, then verifying the hell out of it. 8/16-bit micros, RS-232, no BIOS, aggressive shielding, and an extreme approach to the actor model. For things that need more horsepower, super-simple 32-bit micros, a real-time microkernel, and loads of QA. It's not perfect, and we leave a lot of performance on the table, but as far as security-per-man-hour-expended goes, I'd put it up against anything on the PC any day of the week.
nickpsecurity made a very good comment on designs circulating in the assurance/defense sectors: https://news.ycombinator.com/item?id=15571546
The best part of his comment was the quote from Brian Snow:
"The problem is innately difficult because from the beginning (ENIAC, 1944), due to the high cost of components, computers were built to share resources (memory, processors, buses, etc.). If you look for a one-word synopsis of computer design philosophy, it was and is sharing. In the security realm, the one word synopsis is separation: keeping the bad guys away from the good guys' stuff!
So today, making a computer secure requires imposing a "separation paradigm" on top of an architecture built to share. That is tough! Even when partially successful, the residual problem is going to be covert channels (i.e. side channels). We really need to focus on making a secure computer, not on making a computer secure -- the point of view changes your beginning assumptions and requirements."
I agree Qubes (or other similar systems) are imperfect - partly due to software bugs, partly due to hardware vulnerabilities. But the it clearly is an improvement, if only thanks to the compartmentalization. I'm sure there are potential adversaries that have access to BIOS backdoors, Xen 0-days etc. But well ...