From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Reiner Steib Newsgroups: gmane.emacs.devel,gmane.emacs.gnus.general Subject: Re: New Emacs facilities from Gnus Date: Sun, 04 Nov 2007 22:12:34 +0100 Message-ID: References: <87zly3y4ru.fsf@catnip.gol.com> <87odejy30k.fsf@catnip.gol.com> Reply-To: Reiner Steib NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1194211259 11425 80.91.229.12 (4 Nov 2007 21:20:59 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 4 Nov 2007 21:20:59 +0000 (UTC) Cc: miles@gnu.org, ding@gnus.org, emacs-devel@gnu.org To: Richard Stallman Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Nov 04 22:21:02 2007 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1Iomtx-0003mM-R7 for ged-emacs-devel@m.gmane.org; Sun, 04 Nov 2007 22:21:02 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Iomtn-00050V-5v for ged-emacs-devel@m.gmane.org; Sun, 04 Nov 2007 16:20:51 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Iomtj-00050G-16 for emacs-devel@gnu.org; Sun, 04 Nov 2007 16:20:47 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Iomtf-0004yx-Je for emacs-devel@gnu.org; Sun, 04 Nov 2007 16:20:45 -0500 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Iomtf-0004yg-AG for emacs-devel@gnu.org; Sun, 04 Nov 2007 16:20:43 -0500 Original-Received: from mail.uni-ulm.de ([134.60.1.11]) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1IomtW-0005rY-Da; Sun, 04 Nov 2007 16:20:34 -0500 Original-Received: from bridgekeeper.physik.uni-ulm.de (bridgekeeper.physik.uni-ulm.de [134.60.41.37]) by mail.uni-ulm.de (8.14.1/8.14.1) with ESMTP id lA4LKUCm018785; Sun, 4 Nov 2007 22:20:31 +0100 (MET) Original-Received: from localhost (bridgekeeper.physik.uni-ulm.de [134.60.41.37]) by bridgekeeper.physik.uni-ulm.de (Postfix) with ESMTP id AAC0012C8D; Sun, 4 Nov 2007 22:20:30 +0100 (CET) X-Face: P05mdcZT&lL[-s2=mw~RsllZ0zZAb?vdE}.s (Richard Stallman's message of "Sun, 04 Nov 2007 14:56:48 -0500") User-Agent: Gnus/5.110007 (No Gnus v0.7) Emacs/22.1.50 (gnu/linux) X-DCC-HP_X86_64_8CPU-Metrics: poseidon 1245; Body=4 Fuz1=4 Fuz2=4 X-Virus-Scanned: by amavisd-new X-detected-kernel: by monty-python.gnu.org: Genre and OS details not recognized. X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:82522 gmane.emacs.gnus.general:65549 Archived-At: On Sun, Nov 04 2007, Richard Stallman wrote: > ;;; hashcash.el --- Add hashcash payments to email > ;; Maintainer: Paul Foley > > What does this do? What are hashcash payments? I have attached some explanatory text from wikipedia below (*). In (info "(gnus)Hashcash"), there is also some information. > Will this work with sendmail.el and rmail.el? Probably it wouldn't be difficult to add it there (maybe in `sendmail-send-it'). Bye, Reiner. (*) ,----[ http://en.wikipedia.org/wiki/Hashcash ] | Hashcash | From Wikipedia, the free encyclopedia | | Hashcash is a proof-of-work system designed to limit email spam and | denial of service attacks. It was proposed in March 1997 by Adam | Back [2]. | [...] | | How it works | | Hashcash is a method of adding a textual stamp to the header of an | email to prove the sender has expended a modest amount of CPU time | calculating the stamp prior to sending the email. In other words, as | the sender has taken a certain amount of time to generate the stamp | and send the email, it is unlikely that they are a spammer. The | receiver can, at negligible computational cost, verify that the stamp | is valid. However, the only known way to find a header with the | necessary properties is brute force, trying random values until the | answer is found; though testing an individual string is easy, if | satisfactory answers are rare enough it will require a substantial | number of tries to find the answer. | | The theory is that spammers, whose business model relies on their | ability to send large numbers of emails with very little cost per | message, cannot afford this investment into each individual piece of | spam they send. Receivers can verify whether a sender made such an | investment and use the results to help filter email. | | Technical details | | The header line looks something like [3] | | X-Hashcash: 1:20:060408:adam@cypherspace.org::1QTjaYd7niiQA/sc:ePa | | The header contains: the recipients email address, the date, and | information proving the required computation has been performed. The | presence of the recipients email address forces a new header be | computed for each recipient, the date allows the recipient to record | headers received recently and make sure the header is unique this | email. | | [...] `----