Re: Simple Hardware RNG Idea
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
Simon Spero writes: .... predetermined time interval. External radiation can change, but not bias the parity. If the counter saturates, the counter may be biased towards one parity but the software can easily detect saturation presuming it gets the count. You can use the source in a smoke detector.
On Thu, 5 Oct 1995, Norman Hardy wrote:
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
Simon Spero writes: .... 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 dawn!" Simon
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