From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261452AbULIEwP (ORCPT ); Wed, 8 Dec 2004 23:52:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261453AbULIEwP (ORCPT ); Wed, 8 Dec 2004 23:52:15 -0500 Received: from waste.org ([209.173.204.2]:39589 "EHLO waste.org") by vger.kernel.org with ESMTP id S261452AbULIEwM (ORCPT ); Wed, 8 Dec 2004 23:52:12 -0500 Date: Wed, 8 Dec 2004 20:52:07 -0800 From: Matt Mackall To: David Lang Cc: Bernard Normier , "Theodore Ts'o" , linux-kernel@vger.kernel.org Subject: Re: Concurrent access to /dev/urandom Message-ID: <20041209045207.GB12189@waste.org> References: <006001c4d4c2$14470880$6400a8c0@centrino> <009501c4d4c6$40b4f270$6400a8c0@centrino> <02c001c4d58c$f6476bb0$6400a8c0@centrino> <06a501c4dcb6$3cb80cf0$6401a8c0@centrino> <20041208012802.GA6293@thunk.org> <079001c4dcc9$1bec3a60$6401a8c0@centrino> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 08, 2004 at 07:10:16PM -0800, David Lang wrote: > On Tue, 7 Dec 2004, Bernard Normier wrote: > > >I am just trying to generate UUIDs (without duplicates, obviously). > > > > pulling data from /dev/random or /dev/urandom will not ensure that you > don't have duplicates. No, but this problem can generate duplicates as large as an SHA hash with relative ease when it should be essentially impossible. In other words, it works exactly wrong for UUIDs, which needs fixing. -- Mathematics is the supreme nostalgia of our time.