Date: Sun, 6 Oct 2002 16:21:08 -0300 (ART) From: Fernando Gleiser <fgleiser@cactus.fi.uba.ar> To: =?ISO-8859-1?Q?Mikko_Ty=F6l=E4j=E4rvi?= <mbsd@pacbell.net> Cc: Peter Leftwich <Hostmaster@Video2Video.Com>, FreeBSD Questions LIST <FreeBSD-Questions@FreeBSD.Org> Subject: Re: /dev/urandom is randomly cool Message-ID: <20021006161444.H90352-100000@cactus.fi.uba.ar> In-Reply-To: <20021006005506.W308-100000@atlas.home>
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On Sun, 6 Oct 2002, Mikko Ty=F6l=E4j=E4rvi wrote: > > tr -cd a-zA-Z0-9 < /dev/urandom | dd bs=3D$len count=3D1 2>/dev/null > > Which will give you $len random bytes from the set a-zA-Z0-9 (it reads > a lot more from /dev/urandom than it produces though). yes, and that is bad :( It is not good to mess with /dev/[u]random more than what's really needed, because you can exhaust the entropy pool, and that's a Bad Thing. In your home box, for learning purposes, that's OK, but in a production box which needs a good working prng (for crypto session keys, auth cookies and = the like) it is not acceptable to "eat" all the entropy pool unless you have a very good reason to do so. =09=09=09Fer > > Another answer is, as always, "use perl" :-) > > $.02, > /Mikko > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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