Date: Sun, 2 Feb 2003 17:02:23 +0300 From: "Andrey A. Chernov" <ache@nagual.pp.ru> To: Tim Robbins <tjr@FreeBSD.ORG> Cc: Kris Kennaway <kris@obsecurity.org>, current@FreeBSD.ORG Subject: Re: rand() is broken Message-ID: <20030202140223.GA63836@nagual.pp.ru> In-Reply-To: <20030202134225.GA63673@nagual.pp.ru> References: <20030202070644.GA9987@rot13.obsecurity.org> <20030202090422.GA59750@nagual.pp.ru> <20030202091106.GA72723@rot13.obsecurity.org> <20030202102621.GA60900@nagual.pp.ru> <20030202123035.GB62977@nagual.pp.ru> <20030203001735.A30440@dilbert.robbins.dropbear.id.au> <20030202134225.GA63673@nagual.pp.ru>
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On Sun, Feb 02, 2003 at 16:42:25 +0300, Andrey A. Chernov wrote: > On Mon, Feb 03, 2003 at 00:17:35 +1100, Tim Robbins wrote: > > > > I believe that this change just moves the "bad" seed to 123459876; after > > calling srand() with that seed, each call to rand() returns 0. > > Yes. Nothing better is possible for this formulae and this is documented > in algorithm, some value must be excluded. Excluding 0 is bad only because > srand(0) is commonly used and srand(123459876) is not. This workaround can be improved more, to make generator not stuck ever with 123459876 by simple way: if (seed == 123459876) seed = 123459877; It can be done even with original variant using more simpler patch: if (seed == 0) seed = 123459876; I'll produce and send it a bit later. -- Andrey A. Chernov http://ache.pp.ru/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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