Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id C0242BC1 for ; Wed, 25 Jan 2017 07:15:16 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-yb0-f179.google.com (mail-yb0-f179.google.com [209.85.213.179]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 1278BE3 for ; Wed, 25 Jan 2017 07:15:15 +0000 (UTC) Received: by mail-yb0-f179.google.com with SMTP id f67so382740ybc.2 for ; Tue, 24 Jan 2017 23:15:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=OYaf/ucX5wUWizI5CS+z7ar/dbRc3d8u4viFtS+T81Q=; b=P2D6IkxEGciGd6Z5gtfoT9wu2p20hwppIOccGuIAVToIsU7Wp3Jae4KJgbTqFeTx4M 0yGqitauu+sqVCXt204ATh0f2Is+0HO9nDNkXwjPMXn9KWcCLWEm4HA525GhsbaAQjEL U9lL6GP2dmluhQ95R2M8+jycV8trL0uBqty4QxS2110J1bwSvzsPyfc4CE8pAV9dk9V8 2KH2cky6qs/LDzQvK/FJKDTvxsfb7B2XLxYJgMzf8psBKzAaai40daTDS4W9BdOaF1V1 dNwaQ7wlMksmfxwdmdyyMUR5mg4ddbWf9ynf0Soz5MAilfOw5Y+rHPf6p+7aSJxSX2hF gDMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=OYaf/ucX5wUWizI5CS+z7ar/dbRc3d8u4viFtS+T81Q=; b=tfqAdzlI5UeKkfOD2vY/k/KQaWVGT+miXiw6CMDQL8JTqYJGqBIw8UFMEnEDsIYeqG AEhlBPr/kPqwtqm8uZlYkOCSsrV14JZLWh+09/j+p4yNqA2MMe4gMzQAXS9X12MVJcrc TJMCfV+6hJOrCD2Gi11SMUfTxcyT3fVOrQoHb/atWE16K2Wr3Wgbb6OnOYlGaXzvCDWx rRR/Oyqe9ItuPtmps6lqXGlhMkEO00GKT4568zYMA7DhXamqTwz4q3oZnpbioSh1UIHK Qm7G7iBtz2Z1Ems+T4+wIBFDCxrebVRYf9OGXz8CjRk1LH4U+P8or/0qPf5Pm4qJVUw/ rNgQ== X-Gm-Message-State: AIkVDXKMQQacR1I2+zP5LIH207tMMlhiytn/5YiCf9ARm0MU2A9wbBFA6FlBmIak9XUuaHoXj9woe9GgvVmWTg== X-Received: by 10.37.85.70 with SMTP id j67mr22933451ybb.192.1485328515302; Tue, 24 Jan 2017 23:15:15 -0800 (PST) MIME-Version: 1.0 Received: by 10.37.75.67 with HTTP; Tue, 24 Jan 2017 23:15:14 -0800 (PST) Received: by 10.37.75.67 with HTTP; Tue, 24 Jan 2017 23:15:14 -0800 (PST) In-Reply-To: <311FE02A-F3B5-4F88-B6C8-F0E78CC46903@xbt.hk> References: <311FE02A-F3B5-4F88-B6C8-F0E78CC46903@xbt.hk> From: Natanael Date: Wed, 25 Jan 2017 08:15:14 +0100 Message-ID: To: Johnson Lau Content-Type: multipart/alternative; boundary=001a113ff8588790b40546e5fe9f X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev 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: Wed, 25 Jan 2017 07:15:17 -0000 --001a113ff8588790b40546e5fe9f Content-Type: text/plain; charset=UTF-8 Den 25 jan. 2017 08:06 skrev "Johnson Lau" : What you describe is not a fix of replay attack. By confirming the same tx in both network, the tx has been already replayed. Their child txs do not matter. Read it again. The validation algorithm would be extended so that the transaction can't be replayed, because replaying it in the other network REQUIRES a child transaction in the same block that is valid, a child transaction the is unique to the network. By doing this policy change simultaneously in both networks, old pre-signed transactions *can not be replayed by anybody but the owner* of the coins (as he must spend them immediately in the child transaction). It means that as soon as spent, the UTXO sets immediately and irrevocably diverges across the two networks. Which is the entire point, isn't it? --001a113ff8588790b40546e5fe9f Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Den 25 jan. 2017 08:06 skrev "Johnson Lau" <jl2012@xbt.hk>:
What you= describe is not a fix of replay attack. By confirming the same tx in both = network, the tx has been already replayed. Their child txs do not matter.

Read it again.=C2=A0

The validation algorithm would be extended so that the transaction can&#= 39;t be replayed, because replaying it in the other network REQUIRES a chil= d transaction in the same block that is valid, a child transaction the is u= nique to the network. By doing this policy change simultaneously in both ne= tworks, old pre-signed transactions *can not be replayed by anybody but the= owner* of the coins (as he must spend them immediately in the child transa= ction).=C2=A0

It means t= hat as soon as spent, the UTXO sets immediately and irrevocably diverges ac= ross the two networks. Which is the entire point, isn't it?=C2=A0
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