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From: rbt@sftig.UUCP (R.Thomas)
Newsgroups: net.crypt
Subject: Re: Why no hardware random numbers?
Message-ID: <506@sftig.UUCP>
Date: Wed, 20-Mar-85 18:09:12 EST
Article-I.D.: sftig.506
Posted: Wed Mar 20 18:09:12 1985
Date-Received: Thu, 21-Mar-85 04:48:31 EST
References: <868@utcsri.UUCP> <2139@wateng.UUCP>
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Organization: AT&T Bell Laboratories, Summit, NJ
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> In article <868@utcsri.UUCP> outer@utcsri.UUCP (Richard Outerbridge) writes:
> >
> >So, why do so few supposedly modern computers include a hardware random number
> >generator?  I mean really, every decent library includes at least one flawed-in
> >one-way-or-another pseudo-random generator so its not as though its an esoteric
> >application.  Why no hardware random numbers?
> >-- 
> 
> The Ferranti Ferret (I believe), one of the very early machines (made in
> Canada) had a hardwired random number generator, specifically a gas tube
> in a magnetic field. The problem with this type of random number generator
> is that the sequence of values you get is irreproducible, which can be
> a real drag if you are doing simulations and want to check your results,
> or you want to try two different algorithms on the same sequence of
> numbers. The problem of software random number generation has been well
> studied, it's just that a lot of people go off and do it themselves without
> knowing what they are doing...
> 	-peter
> -- 

The Applesoft BASIC system for the Apple II personal computer has a rather
poor pseudo random number generator, but a great way of acquiring a truely
random seed if the user requests it.  None of this 'start from the clock'
stuff for them (The Apple II doesn't *have* a hardware clock -- so that
wouldn't work.)  The routine that reads user keypresses (and waits for the
user to press one if need be) increments a cell while it waits for input to
become available.  That cell is specificly for seeding the random number
generator.  Is that 'truely random' enough for you?

Rick Thomas