From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 9280FF13 for ; Thu, 18 Jan 2018 19:30:11 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua0-f173.google.com (mail-ua0-f173.google.com [209.85.217.173]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 29471E7 for ; Thu, 18 Jan 2018 19:30:11 +0000 (UTC) Received: by mail-ua0-f173.google.com with SMTP id d1so8495363uak.1 for ; Thu, 18 Jan 2018 11:30:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:from:date:message-id:subject:to; bh=qm+5th/jQ+hWLMvMmU+fYlg+cawJr6Gl/C4WcEtu7l4=; b=O4EF9/S5hYtzEiOaQTDyQHGk/3f8Doo4jU64H4b8rmvOL+UM3w45AX1Zy0yrMqcCoM v745EMTcbYVX2WZW1citbIGHGIaRKJlYLbhSxX8ggFh2chzosiQlpH8MKl/RuaEm5SsW EiGuXRlEUOr/Aw5ZbUjy7q5LPefGFFrIw/A7qlrUmc9ho/ojt49z9nYPKDo6NHRbcyFe 0uYdBwWwd2d/gO13PaWAO3wqicFdv8XgXanI3uUrA5ymUvC33MU3ztk01zo6nBxwyko0 Z7u288OD46Y4/Y0vMSl6hwEO+XH6e3+AQBiKST4N6UUfhZuDY00et71Xr8czEHe6DSHM pDmQ== 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:from:date:message-id:subject :to; bh=qm+5th/jQ+hWLMvMmU+fYlg+cawJr6Gl/C4WcEtu7l4=; b=hseOfvpetMwIPPhzvmuttGgus8+s6x3HpS/a9fQ/sqbHP4zQut/aA7xz7G/gii/RHU LCnBf4XgH3Lz9QY0VcVpE6al6UVTNGH4ueh9x3sZRzCf/DRFW62/aAGL+n+4rvBAW2IN 6JLLhqtzU89x7QcXd54IJYbmT4RHk+neW/Svt6LIaK05t0VAFH2ZIU81ZEpUtwUAzIum 9JEBjeVbIUYePaRSmOwIhuDSXZqWlzLfgoLDMa/98rinyaZQ9ndcdPuUUbzOPV8IsplQ v3lGKY+9vUUnjfWhWjaa+JLVku7yJNZicXbpv4gWwZuXXntn+m34JImldDorYgTAnX4L 4pXg== X-Gm-Message-State: AKwxytfnn0A6U+BXj8OEGlKnHZ/jD9STWEwZ7bAZB92QWZNTwarglhzd chdiIU3Euf2UNFVzBSiWTW/o3KKepxZ1Ym8nbXw= X-Google-Smtp-Source: ACJfBouIt8ujLcV2LS/H+KZ2+3p10c2iGvobvlxFjKkMULF2+7nHr5uNWny6xfIDhjkKqWs4hiVTdFF7h4UIhkZju1E= X-Received: by 10.176.9.210 with SMTP id e18mr5423218uah.21.1516303810078; Thu, 18 Jan 2018 11:30:10 -0800 (PST) MIME-Version: 1.0 Sender: gmaxwell@gmail.com Received: by 10.103.85.152 with HTTP; Thu, 18 Jan 2018 11:30:09 -0800 (PST) From: Gregory Maxwell Date: Thu, 18 Jan 2018 19:30:09 +0000 X-Google-Sender-Auth: wb6uHCr2n63bQ6Ajat0du8UyOqM Message-ID: To: Bitcoin Dev Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: [bitcoin-dev] ScriptPubkey consensus translation 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, 18 Jan 2018 19:30:11 -0000 A common question when discussing newer more efficient pubkey types-- like signature aggregation or even just segwit-- is "will this thing make the spending of already existing outputs more efficient", which unfortunately gets an answer of No because the redemption instructions for existing outputs have already been set, and don't incorporate these new features. This is good news in that no one ends up being forced to expose their own funds to new cryptosystems whos security they may not trust. When sigagg is deployed, for example, any cryptographic risk in it is borne by people who opted into using it. Lets imagine though that segwit-with-sigagg has been long deployed, widely used, and is more or less universally accepted as at least as good as an old P2PKH. In that case, it might be plausible to include in a hardfork a consensus rule that lets someone spend scriptPubkey's matching specific templates as though they were an alternative template. So then an idiomatic P2PKH or perhaps even a P2SH-multisig could be spent as though it used the analogous p2w-sigagg script. The main limitation is that there is some risk of breaking the security assumptions of some complicated external protocol e.g. that assumed that having a schnorr oracle for a key wouldn't let you spend coins connected to that key. This seems like a pretty contrived concern to me however, and it's one that can largely be addressed by ample communication in advance. (E.g. discouraging the creation of excessively fragile things like that, and finding out if any exist so they can be worked around). Am I missing any other arguments?