Date: Sun, 02 Feb 2003 17:32:57 +0000 From: Mark Murray <mark@grondar.org> To: "Andrey A. Chernov" <ache@nagual.pp.ru> Cc: Tim Robbins <tjr@FreeBSD.ORG>, Kris Kennaway <kris@obsecurity.org>, current@FreeBSD.ORG Subject: Re: rand() is broken Message-ID: <200302021732.h12HWvaX048978@grimreaper.grondar.org> In-Reply-To: Your message of "Sun, 02 Feb 2003 16:42:25 %2B0300." <20030202134225.GA63673@nagual.pp.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
"Andrey A. Chernov" writes: > 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 means that this routine has a chance of failing spectacularly. We should not use it. > Ragarding to old formulae, the question is: what is worse, generate > non-random lover bits everytime (old variant) or exclude one seed value > (new variant)? Neither. New RNG is needed. > Of course formulae can be changed to some another algorithm, but keep in > mind that rand() must be simple and speedy. Now used variant is most > simpler, others are much more complex. RC4 is fast. RC4 is simple. Any objections? :-) M -- Mark Murray iumop ap!sdn w,I idlaH To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200302021732.h12HWvaX048978>