[cryptography] Kernel space vs userspace RNG

Krisztián Pintér pinterkr at gmail.com
Sat May 7 11:45:54 EDT 2016




Russell Leidich (at Friday, May 6, 2016, 10:16:12 PM):
> Most of the entropy in a system is manifest in terms of the clock
> skew between direct memory access (DMA) transfers from external
> devices and the CPU core clocks, which unfortunately does not
> traverse the kernel in any directly observable manner.

someone please confirm this, because i'm not a linux expert, but i
don't believe user space code can do dma without the kernel knowing
about it.

also, i assert that such clock drifts provide much less entropy than
you make it look like.


> interrupt timing, unless we extend the definition of "interrupt" to
> include quasiperiodic memory accesses from external clients.

again, i'm no exert in low level kernel stuff, but to my knowledge,
everything happens through interrupts, even dma uses it to report the
end of an operation.




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