building a true RNG (was: Quantum Computing ...)

[Derek Atkins]

"John S. Denker" <jsd at monmouth.com> writes:

> > Source --> Digitizer --> Simple hash --> Whitener (e.g., DES)
> 
> OK, we have DES as an example of a whitener.  
> -- Can somebody give me an example of a "simple hash" 
> that performs "irreversible compression" of the required
> kind?

I can give you a number of examples:  MD5, SHA-1, ....

> -- Isn't the anti-collision property required of even
> the simplest hash?  Isn't that tantamount to a very
> strong "mixing" property?  If there's strong mixing in
> the simple hash function, why do we need more mixing
> in the later "whitening" step?

More mixing is never bad in an RNG..  See RFC1750.

> -- What is meant by "cryptologic strength"?  Strength
> against what kind of attack?  If this means in particular
> the one-way property, why do I need it?  I can understand
> why a !!pseudo!! random symbol generator needs the one-way
> property, to protect its internal state, but since my
> generator has no secret state to protect, why do I need
> any cryptologic properties other than mixing?

I think they probably meant cryptographic strength, but I
don't know what was going through their minds.  What
do people mean by "authentification"?  That's not even
a real world but I see it all the time.  To me, I think
people just don't know the right term to use so they
just put down something that sounds right to them, regardless
of its correctness.

-derek

-- 
       Derek Atkins
       Computer and Internet Security Consultant
       derek at ihtfp.com             www.ihtfp.com

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