From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.emacs.gnus.general/35113 Path: main.gmane.org!not-for-mail From: Florian Weimer Newsgroups: gmane.emacs.gnus.general Subject: Re: `user-mail-address' for message-ids Date: 28 Feb 2001 18:19:48 +0100 Sender: owner-ding@hpc.uh.edu Message-ID: <87hf1erah7.fsf@deneb.enyo.de> References: <20010223133030.B14991@mastaler.com> <87bsrnmrxw.fsf@deneb.enyo.de> <87y9urrn8j.fsf@deneb.enyo.de> NNTP-Posting-Host: coloc-standby.netfonds.no Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: main.gmane.org 1035170906 1244 80.91.224.250 (21 Oct 2002 03:28:26 GMT) X-Complaints-To: usenet@main.gmane.org NNTP-Posting-Date: Mon, 21 Oct 2002 03:28:26 +0000 (UTC) Return-Path: Original-Received: from lisa.math.uh.edu (lisa.math.uh.edu [129.7.128.49]) by mailhost.sclp.com (Postfix) with ESMTP id 77AB4D049D for ; Wed, 28 Feb 2001 12:11:02 -0500 (EST) Original-Received: from sina.hpc.uh.edu (lists@Sina.HPC.UH.EDU [129.7.3.5]) by lisa.math.uh.edu (8.9.1/8.9.1) with ESMTP id LAB32001; Wed, 28 Feb 2001 11:10:46 -0600 (CST) Original-Received: by sina.hpc.uh.edu (TLB v0.09a (1.20 tibbs 1996/10/09 22:03:07)); Wed, 28 Feb 2001 11:09:47 -0600 (CST) Original-Received: from mailhost.sclp.com (postfix@66-209.196.61.interliant.com [209.196.61.66] (may be forged)) by sina.hpc.uh.edu (8.9.3/8.9.3) with ESMTP id LAA24513 for ; Wed, 28 Feb 2001 11:09:34 -0600 (CST) Original-Received: from mail.netic.de (mail.s.netic.de [212.9.160.11]) by mailhost.sclp.com (Postfix) with ESMTP id 65DACD049D for ; Wed, 28 Feb 2001 12:10:03 -0500 (EST) Original-Received: by mail.netic.de (Smail3.2.0.111/mail.s.netic.de) via LF.net GmbH Internet Services via remoteip 212.9.163.88 via remotehost mail.enyo.de with esmtp for mail.gnus.org id m14YA70-001WzAC; Wed, 28 Feb 2001 18:10:02 +0100 (CET) Original-Received: from [192.168.1.2] (helo=deneb.enyo.de) by mail.enyo.de with esmtp (Exim 3.12 #1) id 14YA5I-0003nn-00 for ding@gnus.org; Wed, 28 Feb 2001 18:08:16 +0100 Original-Received: from fw by deneb.enyo.de with local (Exim 3.12 #1) id 14YAGS-0004fI-00 for ding@gnus.org; Wed, 28 Feb 2001 18:19:48 +0100 Original-To: ding@gnus.org In-Reply-To: ("Jason R. Mastaler"'s message of "28 Feb 2001 09:12:24 -0700") User-Agent: Gnus/5.090001 (Oort Gnus v0.01) Emacs/20.7 Precedence: list X-Majordomo: 1.94.jlt7 Original-Lines: 33 Xref: main.gmane.org gmane.emacs.gnus.general:35113 X-Report-Spam: http://spam.gmane.org/gmane.emacs.gnus.general:35113 "Jason R. Mastaler" writes: > > As long as the Gnus algorithm provides enough entropy, message IDs > > generated by Gnus will not cause collisions. > > Can you expand on this a bit further? In particular, is it feasible > to arrive at the sufficient amount of entropy with the LHS only? If only entropy is considered, yes. If we use 130 bits of entropy (which would result in 26 characters in base32), and there are 2^40 message IDs to be assigned under a single domain, the probability of at least one collision among all IDs is around 10^-15 (at least I think so). If there 2^50 message IDs, it goes up to 10^-9, if there are only 2^30, it's approximately 10^-21. If you add four more characters (or 20 bits), the probability in the 2^50 case is around 10^-15 again. If a special domain part is used, only collisions among Gnus users have to be avoided, so if we assume that the random string in the domain part is reused for each message once it has been generated, and there are 2^20 users, with 80 bits of entropy (16 characters), the probability of a collision is around 10^-12. Together with the rest of the domain part and the local-part, we have around 35 characters in a complete. On the other hand, If we put all the entropy goes into the local-part, the domain part is probably rather short (people who have FQDN are going to use the old scheme, I think), and we come out around 35 characters as well. So if my calculations are correct, there is no purely technical reason for putting the entropy in the domain part. However, it's probably out of question to obtain 130 bits of entropy per posted message.