prng change feedback

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Harald Welte laforge at gnumonks.org
Sat Oct 7 06:30:30 UTC 2017


Hi RS,

On Fri, Oct 06, 2017 at 08:43:22AM -0700, ringsignature at riseup.net wrote:
> >> * use getrandom() with GRND_RANDOM flag for K/OP/OPc/Ki generation
> > 
> > I don't have a strong opinion on this one. For GNU/Linux kernel >= 4.8 both
> > /dev/random and /dev/urandom are going through the same CSPRNG so I'm
> > not sure we
> > gain anything by requiring random instead of urandom.
> > 
> 
> That is my understanding as well. The key difference is that you were
> spot on about the pool being drained very seriously - to the point of
> underflowing, thus potentially encountering serious error states. Those
> error states might be a 512 byte buffer with only one random byte, for
> example.

I don't think this is an issue. We can actually do blocking reads for
key generation, once we ever do that.  The speed of programming SIM
cards is probably invariably slower than the amount of randomness we can
get.  That's a one time operation at the time SIM cards are programmed.

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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