Re: use of add_interrupt_randomness in drivers missing in many drivers

From: Horst von Brand (vonbrand@inf.utfsm.cl)
Date: Wed Oct 18 2000 - 15:46:23 EST


daw@mozart.cs.berkeley.edu (David Wagner) said:
> Jeff Garzik wrote:
> >Then you make your local random pool vulnerable to external
> >manipulation, to a certain extent...

> Adding more bits to the pool should never hurt; the cryptographic
> mixing ensures this. What _can_ hurt is adding predictable bits but
> (erroneously) bumping up the entropy counter.

The problem that was being discussed is not generating enough entropy on
certain machines (f.ex. a router running out of RAM: No mouse, no kbd, no
disk, ...).

> So, if you're not sure whether those bits are unpredictable and random
> or not, the right thing to do is to mix 'em into the pool, but don't
> bump the entropy counter. The greater your diversity of sources, the
> less likely it is that you encounter a catastrophic randomness failure.

Adding stuff that adds no entropy (or at least doesn't add to the estimated
entropy pool) is just a waste of effort, AFAIKS.

-- 
Dr. Horst H. von Brand                       mailto:vonbrand@inf.utfsm.cl
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513
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