Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261925AbUK3Ci0 (ORCPT ); Mon, 29 Nov 2004 21:38:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261943AbUK3Chs (ORCPT ); Mon, 29 Nov 2004 21:37:48 -0500 Received: from mail1.webmaster.com ([216.152.64.168]:18706 "EHLO mail1.webmaster.com") by vger.kernel.org with ESMTP id S261956AbUK3Ccp (ORCPT ); Mon, 29 Nov 2004 21:32:45 -0500 From: "David Schwartz" To: "Bernard Normier" Cc: , Subject: RE: Concurrent access to /dev/urandom Date: Mon, 29 Nov 2004 18:31:50 -0800 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Authenticated-Sender: joelkatz@webmaster.com X-Spam-Processed: mail1.webmaster.com, Mon, 29 Nov 2004 18:08:14 -0800 (not processed: message from trusted or authenticated source) X-MDRemoteIP: 206.171.168.138 X-Return-Path: davids@webmaster.com X-MDaemon-Deliver-To: linux-kernel@vger.kernel.org Reply-To: davids@webmaster.com X-MDAV-Processed: mail1.webmaster.com, Mon, 29 Nov 2004 18:08:18 -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1019 Lines: 28 > On Mon, 29 Nov 2004, Bernard Normier wrote: > > >>> I use /dev/urandom to generate UUIDs by reading 16 random bytes from > >>> /dev/urandom (very much like e2fsprogs' libuuid). > >> > >> Why not use /dev/random for such data instead? > > > > A UUID generator that blocks from time to time waiting for > entropy would not > > be usable. > > Especially when used on a box without any effective entropy source - like > praktically most cheap servers stashed away into some rack. Assuming most of your cheap servers are running some version of the Intel Pentium or comparable, they have wonderful entropy sources. Nobody can predict the oscillator offset between the crystals in the network cards on both ends and the TSC. This entropy source is mined by the kernel. DS - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/