[Buildroot] [PATCH] initscripts: Make installation of S20urandom optional.

[Yann E. MORIN <yann.morin.1998@free.fr>]

Peter, All,

On 2020-07-19 14:09 +0200, Peter Seiderer spake thusly:
> On Sun, 19 Jul 2020 13:49:50 +0200, "Yann E. MORIN" <yann.morin.1998@free.fr> wrote:
[--SNIP--]
> > I would however believe this script is not interesting at all. In fact,
> > an ambedded device seldom reboots nicely; instead, it is most often a
> > hard-reboot (with a power cycle). In that case, the script would have no
> > chance whatsoever to save the current seed before shutdown, thus on next
> > boot we would restore a seed that would have already been used, thus
> > defeating randomness to begin with; worse, it would give people a sense
> > of security where there would in fact be a hole.
> 
> This is a very limited view of the buildroot use-cases, I believe there
> are although some, call it 'mid-range' embedded systems, with a proper
> power-down button shutting down the system before killing the power
> (or at least the use-case of two of my customer projects)...

Yeah, but still, is saving-n-restoring the seed the sanest thing to do?
If your devices are that well engineered (yeah!), you probably have a
good source of randmoness (proably HW, or with rng-tools et al), so
don't need to save-n-restore the seed...

Even for well-designed devices, that can be sanely powered-off-then-on,
there is always the possibility that the power completely goes out, and
thus the seed would be re-used.

Re-using a seed is one of the worst thing one may do about randomness:
it is very, very bad, because it gives people a false sense of security
"Hey! I'm saving and restoring the seed, so no two boots will have the
same random sequence! Woohoo!" Boom, wrong...

So I still stand on my position that we should get rid of S20random.

Regards,
Yann E. MORIN.

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