Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 06E82C9C for ; Fri, 23 Sep 2016 14:37:45 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mx-out02.mykolab.com (mx.kolabnow.com [95.128.36.1]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id C585D28C for ; Fri, 23 Sep 2016 14:37:43 +0000 (UTC) X-Virus-Scanned: amavisd-new at kolabnow.com X-Spam-Score: -2.9 X-Spam-Level: X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 Received: from mx04.mykolab.com (mx04.mykolab.com [10.20.7.102]) by mx-out02.mykolab.com (Postfix) with ESMTPS id EB141637D6 for ; Fri, 23 Sep 2016 16:37:40 +0200 (CEST) From: Tom To: bitcoin-dev@lists.linuxfoundation.org Date: Fri, 23 Sep 2016 16:37:39 +0200 Message-ID: <2403444.9CSRyRIcH2@garp> In-Reply-To: <201609230957.03138.luke@dashjr.org> References: <201609230957.03138.luke@dashjr.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Fri, 23 Sep 2016 14:54:45 +0000 Subject: Re: [bitcoin-dev] BIP draft: OP_CHECKBLOCKATHEIGHT X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Sep 2016 14:37:45 -0000 On Friday 23 Sep 2016 09:57:01 Luke Dashjr via bitcoin-dev wrote: > This BIP describes a new opcode (OP_CHECKBLOCKATHEIGHT) for the Bitcoin > scripting system to address reissuing bitcoin transactions when the coins > they spend have been conflicted/double-spent. > > https://github.com/luke-jr/bips/blob/bip-cbah/bip-cbah.mediawiki Can you walk us through a real live usecase which this solves? I read it and I think I understand it, but I can't see the attack every giving the attacker any benefit (or the attacked losing anything).