[Soekris] 4801, Linux, and entropy

[Poul-Henning Kamp]

In message <34A9C69B-DFEE-4ECD-ACD4-80C239E11E21 at netgate.com>, Jim Thompson wri
tes:


>There are recent patches to the 2.6 kernel line that implement  
>Ferguson's Fortuna
>http://en.wikipedia.org/wiki/Fortuna_(PRNG)

Not to start a major flamewar here or anything, but I consider it
a significant mistake that Fortuna is implemented with 32 accumulators,
rather than using a prime number (say 31 ?).

Most source of entropy have strong power-of-two nature so any multiple
of two can give rise to sorting of entropy.  Using a number on the
from 2^n can only make this even worse.

Mind you, this is not a major hole in Fortuna, this is probably not
even a hole at all, but I think it is a mistake which indicates
that the author has a too theoretical concept of entropy sources
in computers.

Otherwise I quite like the fortuna design.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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Never attribute to malice what can adequately be explained by incompetence.