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Date: Thu, 14 Dec 2000 22:56:00 -0800
From: Kris Kennaway <kris@FreeBSD.ORG>
To: Peter Jeremy <peter.jeremy@alcatel.com.au>
Cc: hackers@FreeBSD.ORG, sheldonh@uunet.co.za, arnold@skeeve.com
Subject: Re: BSD random for Alpha?
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In-Reply-To: <20001204092348.A92196@gsmx07.alcatel.com.au>; from peter.jeremy@alcatel.com.au on Mon, Dec 04, 2000 at 09:23:48AM +1100
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On Mon, Dec 04, 2000 at 09:23:48AM +1100, Peter Jeremy wrote:

> >Hi.  I've switched to the new random.c you sent me for gawk.  My
> >Linux/Alpha Guru reports that the code in it assumes that sizeof(long)
> >is always 4, and one particular test doesn't "look" very random on
> >the Alpha.
> >
> >My question is, is there a better version of random that can deal
> >with both 32 and 64 bit systems in the same source code?  Would
> >the NetBSD people maybe have such a thing?
> 
> Try a Fibonacci-sequence random number generator (they're mentioned
> in Knuth).  The general form is:
> 
> X[n] = (X[n-j] + X[n-k]) mod m

I think this would be bad - for a general-purpose language like awk we
should be using a cryptographic-strength PRNG like arc4random() or
/dev/urandom so that people can use it for any purpose. 64-bit
cleanliness can presumably be taken care of easily enough.

Kris


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