> not just computer experts.

Which is itself misleading - no living expert understands a computer system end to end, from silicon to microcode to code and compiler, not to mention the massive chain that went into making the code running on the machines.

That's all assuming the black box the expert is looking at is the same one he thinks he understands, and no chip- [1] or compiler-level [2] vulnerabilities were inserted, or the whole thing wasn't simply replaced with an identical-looking device.

[1] https://www.schneier.com/blog/archives/2018/03/adding_backdo...

[2] https://www.win.tue.nl/~aeb/linux/hh/thompson/trust.html