Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262230AbVAJNDm (ORCPT ); Mon, 10 Jan 2005 08:03:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262231AbVAJNDm (ORCPT ); Mon, 10 Jan 2005 08:03:42 -0500 Received: from [195.23.16.24] ([195.23.16.24]:60814 "EHLO bipbip.comserver-pie.com") by vger.kernel.org with ESMTP id S262230AbVAJNDk (ORCPT ); Mon, 10 Jan 2005 08:03:40 -0500 Message-ID: <41E27D29.2040001@grupopie.com> Date: Mon, 10 Jan 2005 13:03:37 +0000 From: Paulo Marques Organization: Grupo PIE User-Agent: Mozilla Thunderbird 0.7.1 (X11/20040626) X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux-os@analogic.com Cc: "Patrick J. LoPresti" , Linux kernel Subject: Re: /dev/random vs. /dev/urandom References: <20050107190536.GA14205@mtholyoke.edu> <20050107213943.GA6052@pclin040.win.tue.nl> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1488 Lines: 39 linux-os wrote: > [...] > One is free to use any number of samples. The short number of samples > was DELIBERATELY used to exacerbate the problem although a number > or nay-sayers jumped on this in an attempt to prove that I don't > know what I'm talking about. It seems to me that you actually don't. Since this is a *uniform* distribution in the range [0..2^N[, than any of those N bits must also show a uniform distribution, or the distribution of the sum of the bits wouldn't be uniform. (isn't this obvious?) It would be different of course, if this was not a uniform distribution, or the range was not a power of 2... Of course, I agree that throwing away 5 bits in every byte of perfect entropy that the kernel worked so hard to gather is just wrong, but the randomness of the result is not the reason why. > In the first place, the problem was to display the error of using > an ANDing operation to truncate a random number. In the limit, > one could AND with 0 and show that all randomness has been removed. Not really.. you just get a perfect random uniform distribution if the range [0..0] :) -- Paulo Marques - www.grupopie.com "A journey of a thousand miles begins with a single step." Lao-tzu, The Way of Lao-tzu - 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/