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Re: lack of entropy



Marek Podmaka schrieb:
Hello,

Wednesday, November 15, 2006, 2:03:34, "Uwe A. P. Würdinger" wrote:

apt-get install rng-tools
echo 'RNGDOPTIONS="-b -r /dev/urandom"' >> /etc/default/rng-tools
/etc/init.d/rng-tools start

I just did this before 2 days :)

But my question is how bad this is?
Depends how random your random has to be. I wouldn't use it on a system that handles real sesitive data like credit card data etc. but it's good enough for a webmail or community site.

You could use hardware entropy pools if you need more random random or in a big setup with lots of entropy needs you could use a dedicated mashine as entropy pool for all the servers.
We do that in a couple of installations :-)
We are in fact trying to generate some entropy for /dev/random from
/dev/urandom. I think urandom output is determined by the /dev/random
state... And we are reading from urandom when the entropy is low (ok,
maybe we read in ahead of this). But aren't we creating some loop
here? But as a temp solution it is good :)
Honestly, I don't have the time right now to look into the implementation of /dev/random and /dev/urandom and
the one who would know is on vacation right now.

But hey look in the source yourself if you really wonna know.

greets Uwe
--
Uwe A. P. Würdinger
IT Security Engineer
X-tec GmbH
http://www.x-tec.de



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