Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 204FDB2A for ; Thu, 26 Jan 2017 10:55:45 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-lf0-f45.google.com (mail-lf0-f45.google.com [209.85.215.45]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 6FE8CE2 for ; Thu, 26 Jan 2017 10:55:44 +0000 (UTC) Received: by mail-lf0-f45.google.com with SMTP id x1so56809278lff.0 for ; Thu, 26 Jan 2017 02:55:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:content-transfer-encoding; bh=rKdwhi2J/qdwlqkjfKHXK5Pt946mDdK/yz5v0XV7Pu4=; b=EEguay/ZHm/9BV4HCn/B5gbjjnU8hfxCoin9fZvSFyyhSdobm93gYyLv6ebu4qKLeS jxB000bjni2TPJRtCBzyJgvW8iO6v42fU1k81ok9fL6gMSxI4Sz2AuzGZ5YnYytt3UaR vgS81YBut83MSW+/ejcoQpirYRl4n4aeuijyU6238OYruIgtpiRJdPnDTmhjjRtne/yO 63e9V8CTrnmzeK1cHywMctoJPXdG0gdN7ed9TBF4YsXq1xIlA6R8qTtmE12L0fzKPwsk qBgHBIEWVkB+1ipw7lYHwQkyBeD8xjj+9Wzurz9H6oRM6kE6VimH2wmSfGE/4qdaiz/l gLSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:content-transfer-encoding; bh=rKdwhi2J/qdwlqkjfKHXK5Pt946mDdK/yz5v0XV7Pu4=; b=s1HrnH+EGs8sJ70SH0/w3RPgxhqxEC6/KapnOxi+7oc6oDY+XflazbS46QmFMfwK3L WMeTh6Mc4wiaEI8pQcU6qNWPON7ZWwoTq9nVoWMGdQ6ERivKOnJXWuFYkBptVVmRFY+T 0fE3+SA1WYS//pClNxZqIKtG9cDF+HxnuPHKXkeVSYJjjtyIkEHlWoUZFIA1yR225AOk M2/bLamqjup3XNtdHkx+qzdF6cBiyAVApyrnXapxccHa7NMR1l0xZ8KMztz7K0U+9XWw U/KI+cqvE2jZqvlHpq7fW3HJloVUWUSx/pfhvMBV3exwV/o+6XEdk8lXmU9UpOw5UPGF ZYjg== X-Gm-Message-State: AIkVDXIBusXXJtYiNMCqJx+qGBbHtwmIAFDcz95kdr11qi5iLPiR0ZcHI7c00npnaTS5tixyIVfzU10ZdRdlQw== X-Received: by 10.25.166.131 with SMTP id p125mr655058lfe.142.1485428142496; Thu, 26 Jan 2017 02:55:42 -0800 (PST) MIME-Version: 1.0 Sender: edmund.edgar@gmail.com Received: by 10.25.16.222 with HTTP; Thu, 26 Jan 2017 02:55:41 -0800 (PST) In-Reply-To: <7AF0AA6D-C144-4D0C-B5FC-0BC2C79C0D26@xbt.hk> References: <93ac7433-470c-d59e-e085-29f0f1613676@mattcorallo.com> <7AF0AA6D-C144-4D0C-B5FC-0BC2C79C0D26@xbt.hk> From: Edmund Edgar Date: Thu, 26 Jan 2017 19:55:41 +0900 X-Google-Sender-Auth: m4laKuGHd3Yg2NDkghltaqvBQZI Message-ID: To: Bitcoin Protocol Discussion Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Thu, 26 Jan 2017 11:15:03 +0000 Subject: Re: [bitcoin-dev] Anti-transaction replay in a hardfork 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: Thu, 26 Jan 2017 10:55:45 -0000 On 26 January 2017 at 18:20, Johnson Lau via bitcoin-dev wrote: >You can=E2=80=99t anti-replay if you don=E2=80=99t even know a hardfork mi= ght happen. And I think your hypothesis (replay reduces the incentive of sp= lit) is not supported by the ETC/ETH split. I agree with the general point you're making, but you *could* anti-replay without knowing about the fork, at least from a few dozen blocks into it. For example you could allow transactions to specify a recent block hash (or some of the bytes thereof) and declare that they want to be invalid if that block isn't in the parent chain. This would potentially have benefits beyond economic hard-fork situations: As a general principle, if the network that you're transacting with doesn't look like the one you think you're transacting with, you're going to have a bad day. --=20 --=20 Edmund Edgar Founder, Social Minds Inc (KK) Twitter: @edmundedgar Linked In: edmundedgar Skype: edmundedgar http://www.socialminds.jp Reality Keys @realitykeys ed@realitykeys.com https://www.realitykeys.com