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Re: Simple Hardware RNG Idea
On Thu, 5 Oct 1995, Norman Hardy wrote:
> Simon Spero writes:
> > What about a beam of high intensity ionising radiation aimed at the
> > detector?
> You presumably use the oddness of the count for your random bit in some
> predetermined time interval. External radiation can change, but not bias
> the parity. If the counter saturates, the counter may be biased towards one
Hmmm. But isn't this method slightly biased? If the probability of N
events < the probability of N+1 events, wouldn't you need a large number
of events per bit to make the bias insignificant?
The measurement I was thinking of (which would have been susceptible to
the external attack) was to measure the interval between events, and
convert that to a uniform distribution. That's probably trying to get too
many random bits per event, but does let you use much lower level sources.
BTW, I was just having dinner with a bunch of guys from HP labs in
Bristol, UK, and the subject of hardware RNGs came up. The idea of
Strontium-90 as the next computer consumable has a certain appeal- the
designating brandname is "Omnisource".
"Are you having trouble scintillating? With Omnisource, you can scin till