[Pkg-sysvinit-devel] Saving of /dev/urandom seed at Debian bootup

[Mikko Hänninen]

Hi,

While investigating randomness and /dev/urandom on Debian Linux,
I came across this comment (by you, I think):

  # Hm, why is the saved pool re-created at boot? [pere 2009-09-03]

in /etc/init.d/urandom, part of initscripts in Debian Squeeze.

Hopefully I've inferred correctly who to contact about it. I know the
question is nearly three years old, but in case nobody has provided
the answer to you yet, and you're still curious, then here's my guess:


The seed is meant to carry entropy across system reboots. So normally
it is written at shutdown and read at startup. However, consider the
situation where the normal shutdown is not done (abrupt poweroff, or
similar). In this case the seed is not written, and several consecutive
startups would use the same seed data. If the shutdown problem persists
then the seed file won't ever do its job, because the contents are
always the same on every boot up.

Re-generating the seed file at boot time works around this problem.


My background is that I'm just another computer hobbyist and don't have
any kind of specialty in randomness or such. So the above is just a
non-informed guess.


Best regards,
Wizzu
-- 
|| Mikko Hänninen, aka. Wizzu  // sig at wizzu.com // http://www.wizzu.com/
|| computer hobbyist - net.addict - music enthusiast - swordsman
|| Other interests: Linux, fantasy & scifi, roleplaying
If you have to run heating in winter, you don't own enough computers.