Re: more random device badness in 2.6.18 :(

From: Gabor Gombas
Date: Tue Oct 10 2006 - 16:51:12 EST


On Tue, Oct 10, 2006 at 08:08:32PM +0200, Paul Wouters wrote:

> Since hardware random is not transparently added to /dev/random's entropy,
> applications such as Openswan need to test for the availability of the
> seperate device file (not a good design imho). So Openswan will use
> /dev/hw_random if available.

Why should Openswan touch /dev/hw_random directly?

> Every call to /dev/hw_random gives that one (not very random!) line of output,
> and then nothing more ever. A call to /dev/random still works:

$ apt-cache show rng-tools
[...]
The rngd daemon acts as a bridge between a Hardware TRNG (true random number
generator) such as the ones in some Intel/AMD/VIA chipsets, and the kernel's
PRNG (pseudo-random number generator).
.
It tests the data received from the TRNG using the FIPS 140-2 (2002-10-10)
tests to verify that it is indeed random, and feeds the random data to the
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
kernel entropy pool.
[...]

There is a good reason why /dev/hw_random is different from /dev/random...

Gabor

--
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MTA SZTAKI Computer and Automation Research Institute
Hungarian Academy of Sciences
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