Re: Simple Hardware RNG Idea

> Perry writes, regarding alpha decay counts for random numbers:
> 
> > And, as I noted, there are RS232 interfaceable radiation detectors you
> > can buy off the shelf -- no hardware hacking needed.
> 
> As far as a radiation source goes, the Americium 241 source from a cheap
> smoke detector is just dandy. A while ago, I took one into the lab and
> put it on a scintillating counter and got alpha hits at roughly
> half-microsecond intervals. It was a while ago, so I forget how this compared
> to the rating in Curies on the package. But that would be fine for a
> low-to-moderate bandwidth RNG.

I was thinking about this the other day and wondered if it wouldn't be
cheap and relatively easy to build a board that samples and sums
several randomly selected signals on various frequencies on the AM
broadcast spectrum.  This should catch stations in nearly all
metropolitan (and most rural areas as well) and would require that
someone be able to broadcast at multiple frequencies to "cheat" it.

Perhaps this would be affected by RF interference from the motherboard
itself.  If so, could the RF radiation from the motherboard itself be
used to generate random numbers?

-- 
Dave Dittrich                  Client Services, Computing & Communications
dittrich@cac.washington.edu    University of Washington

<a href="http://www.washington.edu/People/dad/">
Dave Dittrich / dittrich@cac.washington.edu</a>

Dave Dittrich writes:
> 
> > Perry writes, regarding alpha decay counts for random numbers:
> > 
> > > And, as I noted, there are RS232 interfaceable radiation detectors you
> > > can buy off the shelf -- no hardware hacking needed.

> I was thinking about this the other day and wondered if it wouldn't be
> cheap and relatively easy to build a board that samples and sums
> several randomly selected signals on various frequencies on the AM
> broadcast spectrum.

Radio signals can be interfered with or listened to -- never
underestimate the opponent. Computer interfaced radiation detectors,
in spite of Tim's claim to the contrary, are pretty cheap and very
hard to interfere with.

Perry

On Tue, 3 Oct 1995, Perry E. Metzger wrote:
> 
> Radio signals can be interfered with or listened to -- never
> underestimate the opponent. Computer interfaced radiation detectors,
> in spite of Tim's claim to the contrary, are pretty cheap and very
> hard to interfere with.

What about a beam of high intensity ionising radiation aimed at the 
detector? Since we're dealing with lo intensity sources, this could force
the RNG into a small part of its range. Beware of black helicopters 
carrying cyclotrons :-)

Simon

Simon Spero writes:
> On Tue, 3 Oct 1995, Perry E. Metzger wrote:
> > Radio signals can be interfered with or listened to -- never
> > underestimate the opponent. Computer interfaced radiation detectors,
> > in spite of Tim's claim to the contrary, are pretty cheap and very
> > hard to interfere with.
> 
> What about a beam of high intensity ionising radiation aimed at the 
> detector?

If you are paranoid, put the detector in a lead box and you are
done. Its not hard to get the lead thick enough that tampering
attempts would be noticed very easily. Trying to shield an object from
radio signals and still manage to get meaningful numbers out (rather
than self generated signal) is a hard problem, but this can be done by
a high school student.

Perry

>What about a beam of high intensity ionising radiation aimed at the 
>detector? Since we're dealing with lo intensity sources, this could force
>the RNG into a small part of its range. Beware of black helicopters 
>carrying cyclotrons :-)

Thermal noise is a much less hazardous mechanism. Ionising radiation is a pain to deal 
with, it is something one generally attempts to get rid of in a fabrication process if 
possible. Environmental radiation is a strong polluting source.

There are plenty of other quantum phenomena which can be tapped. Essentially all one 
needs to do is to build a very high gain amplifier "baddly". The main difficulty is 
removing bias. One can either go through filtering hohaa or use say MD5. The trully 
paranoid could Xor together an odd number of  MD5 samples just in case there were bit 
pattern dependencies.

	Phill

hallam@w3.org writes:
> 
> There are plenty of other quantum phenomena which can be
> tapped. Essentially all one needs to do is to build a very high gain
> amplifier "baddly". The main difficulty is removing bias.

The main difficulty is that it is extremely hard to prove to yourself
that you are amplifying a quantum phenomenon and not deterministic
noise from the rest of the circuits in the machine or outside it. As
I've said repeatedly, its nearly impossible to get this wrong with a
radiation detecting mechanism, but its very very hard to get it right
with most common mechanisms.

Perry