From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754077AbXLJXHZ (ORCPT ); Mon, 10 Dec 2007 18:07:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751976AbXLJXHO (ORCPT ); Mon, 10 Dec 2007 18:07:14 -0500 Received: from torres.zugschlus.de ([85.214.68.41]:53531 "EHLO torres.zugschlus.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751212AbXLJXHN (ORCPT ); Mon, 10 Dec 2007 18:07:13 -0500 Date: Tue, 11 Dec 2007 00:06:43 +0100 From: Marc Haber To: Matt Mackall Cc: Eric Dumazet , Alan Cox , Adrian Bunk , linux-kernel@vger.kernel.org, "David S. Miller" Subject: Re: Why does reading from /dev/urandom deplete entropy so much? Message-ID: <20071210230643.GC32133@torres.zugschlus.de> References: <20071204114125.GA17310@torres.zugschlus.de> <20071204161811.GB15974@stusta.de> <20071204164720.6e4dc2c4@the-village.bc.nu> <475599D6.4030008@cosmosbay.com> <20071205212646.GP17536@waste.org> <20071209124200.GA31147@torres.zugschlus.de> <20071209161605.GX19691@waste.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071209161605.GX19691@waste.org> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 09, 2007 at 10:16:05AM -0600, Matt Mackall wrote: > On Sun, Dec 09, 2007 at 01:42:00PM +0100, Marc Haber wrote: > > On Wed, Dec 05, 2007 at 03:26:47PM -0600, Matt Mackall wrote: > > > The distinction between /dev/random and /dev/urandom boils down to one > > > word: paranoia. If you are not paranoid enough to mistrust your > > > network, then /dev/random IS NOT FOR YOU. Use /dev/urandom. > > > > But currently, people who use /dev/urandom to obtain low-quality > > entropy do a DoS for the paranoid people. > > Not true, as I've already pointed out in this thread. I must have missed this. Can you please explain again? For a layman it looks like a paranoid application cannot read 500 Bytes from /dev/random without blocking if some other application has previously read 10 Kilobytes from /dev/urandom. Greetings Marc -- ----------------------------------------------------------------------------- Marc Haber | "I don't trust Computers. They | Mailadresse im Header Mannheim, Germany | lose things." Winona Ryder | Fon: *49 621 72739834 Nordisch by Nature | How to make an American Quilt | Fax: *49 3221 2323190