* [Buildroot] get initial entropy from the host
@ 2018-05-30 0:31 Enoch W.
2018-05-30 6:14 ` Peter Korsgaard
0 siblings, 1 reply; 2+ messages in thread
From: Enoch W. @ 2018-05-30 0:31 UTC (permalink / raw)
To: buildroot
Hi,?
Thanks for making Linux so easy to build [that is, when it works ;-) ]
package/initscripts/init.d/S20urandom doesn't have readily available entropy on its first boot.
May I suggest initializing /dev/urandom from host generated random-seed. I do it now via my board post-build.sh as follows.
IMHO it should be done as standard.
umask 077
dd if=/dev/urandom of=${TARGET_DIR}/etc/random-seed count=1
Thanks, Enoch.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Buildroot] get initial entropy from the host
2018-05-30 0:31 [Buildroot] get initial entropy from the host Enoch W.
@ 2018-05-30 6:14 ` Peter Korsgaard
0 siblings, 0 replies; 2+ messages in thread
From: Peter Korsgaard @ 2018-05-30 6:14 UTC (permalink / raw)
To: buildroot
>>>>> "Enoch" == Enoch W <ixew@hotmail.com> writes:
> Hi,?
> Thanks for making Linux so easy to build [that is, when it works ;-) ]
You're welcome ;)
> package/initscripts/init.d/S20urandom doesn't have readily available entropy on its first boot.
> May I suggest initializing /dev/urandom from host generated
> random-seed. I do it now via my board post-build.sh as follows.
> IMHO it should be done as standard.
> umask 077
> dd if=/dev/urandom of=${TARGET_DIR}/etc/random-seed count=1
The problem is that if you have a lot of devices running the same build
they will have the same entropy. We used to have a hardcoded default
value for /etc/random-seed which we removed back in 2015:
commit ed0b44fdcecd2a703d2c1b8134375e19a2b7f867
Author: Baruch Siach <baruch@tkos.co.il>
Date: Wed Jul 8 08:24:11 2015 +0300
system/skeleton: remove random-seed
Seeding the entropy pool with a known seed makes more harm than good. This is
especially bad for when /etc is not on a persistent writable storage, so the
entropy pool is seeded with the same value on every boot. Just drop it.
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
--
Bye, Peter Korsgaard
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2018-05-30 0:31 [Buildroot] get initial entropy from the host Enoch W.
2018-05-30 6:14 ` Peter Korsgaard
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