Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id DEEE7C7C for ; Wed, 9 May 2018 21:16:33 +0000 (UTC) X-Greylist: delayed 00:17:13 by SQLgrey-1.7.6 Received: from outmail149077.authsmtp.com (outmail149077.authsmtp.com [62.13.149.77]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 24B3A680 for ; Wed, 9 May 2018 21:16:32 +0000 (UTC) Received: from mail-c245.authsmtp.com (mail-c245.authsmtp.com [62.13.128.245]) by punt20.authsmtp.com. (8.15.2/8.15.2) with ESMTP id w49KxILK061595; Wed, 9 May 2018 21:59:18 +0100 (BST) (envelope-from user@petertodd.org) Received: from petertodd.org (ec2-52-5-185-120.compute-1.amazonaws.com [52.5.185.120]) (authenticated bits=0) by mail.authsmtp.com (8.15.2/8.15.2) with ESMTPSA id w49KxGw4021247 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 9 May 2018 21:59:17 +0100 (BST) (envelope-from user@petertodd.org) Received: from [127.0.0.1] (localhost [127.0.0.1]) by petertodd.org (Postfix) with ESMTPSA id 1B8D240116; Wed, 9 May 2018 20:59:16 +0000 (UTC) Received: by localhost (Postfix, from userid 1000) id 04BA42211F; Wed, 9 May 2018 16:59:14 -0400 (EDT) Date: Wed, 9 May 2018 16:59:14 -0400 From: Peter Todd To: Johnson Lau Message-ID: <20180509205913.5vpivaudj5e3bnih@petertodd.org> References: <87po25lmzs.fsf@rustcorp.com.au> <20180509192733.6aif4wapolbb5z7c@petertodd.org> <4E64F59E-3367-4C4E-A9FB-48ED568BC2D3@xbt.hk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="i32q7qdkfydayaoi" Content-Disposition: inline In-Reply-To: <4E64F59E-3367-4C4E-A9FB-48ED568BC2D3@xbt.hk> User-Agent: NeoMutt/20170113 (1.7.2) X-Server-Quench: d6aac69d-53cb-11e8-a283-9cb654bb2504 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZIVwkA IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdgsUFVQNAgsB Am4bWVVeVVR7WGQ7 bghPaBtcak9QXgdq T0pMXVMcUwFhelR2 QRoeUBhwcwIIeX5y ZkUsCnYKDRd8fBJg R00HR3AHZDJodTEd WENFflAGdgZOLE1H b1B7GhFYa3VsNCMk FAgyOXU9MCtqYAFc QQALIho1eXE3JAMR DwseFDMjFFcJEE3Y X-Authentic-SMTP: 61633532353630.1039:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 52.5.185.120/25 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,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] Making OP_TRUE standard? 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, 09 May 2018 21:16:34 -0000 --i32q7qdkfydayaoi Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 10, 2018 at 04:19:31AM +0800, Johnson Lau wrote: >=20 >=20 > > On 10 May 2018, at 3:27 AM, Peter Todd wrote: > >=20 > > On Thu, May 10, 2018 at 01:56:46AM +0800, Johnson Lau via bitcoin-dev w= rote: > >> You should make a =E2=80=9C0 fee tx with exactly one OP_TRUE output=E2= =80=9D standard, but nothing else. This makes sure CPFP will always be need= ed, so the OP_TRUE output won=E2=80=99t pollute the UTXO set > >>=20 > >> Instead, would you consider to use ANYONECANPAY to sign the tx, so it = is possible add more inputs for fees? The total tx size is bigger than the = OP_TRUE approach, but you don=E2=80=99t need to ask for any protocol change. > >>=20 > >> In long-term, I think the right way is to have a more flexible SIGHASH= system to allow people to add more inputs and outputs easily. > >=20 > > I don't think that will work, as a zero-fee tx won't get relayed even w= ith > > CPFP, due to the fact that we haven't yet implemented package-based tx > > relaying. > >=20 > > --=20 > > https://petertodd.org 'peter'[:-1]@petertodd.org >=20 > My only concern is UTXO pollution. There could be a =E2=80=9CCPFP anchor= =E2=80=9D softfork that outputs with empty scriptPubKey and 0 value are spe= ndable only in the same block. If not spent immediately, they become invali= d and are removed from UTXO. But I still think the best solution is a more = flexible SIGHASH system, which doesn=E2=80=99t need CPFP at all. I don't see any reason why UTXO pollution would be a special concern so lon= g as those outputs are subject to the same dust rules as any other output is. --=20 https://petertodd.org 'peter'[:-1]@petertodd.org --i32q7qdkfydayaoi Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEFcyURjhyM68BBPYTJIFAPaXwkfsFAlrzYRsACgkQJIFAPaXw kfuHBggAjWWAfa3aO5C9CsPRLuUwrhjAT4hZCQryyWd1KIuqcv2K/C+NEYkwac7m oT+LdXXTCuHxxVaqOLplXLZn7FZX1uwKSAzben1DFNOQKrky4i8uVYFWa3nojsCg t2sgFo5OzTiooZsmcrKixjI6irVKs6SHCsUTnUZNsPD4Mn6q4guyg3N701sl8NPp R84z8GIQlgRsCh3t/ssUABMzqGnPG2grU/FUySq8q4kg26HjnevyBczc0zjz+Vl5 Xb1Wy2kjPQjMGZAeO88RiNrX743asXPtcd8KdM8A8IXQmDdzf/31XTrJJ43rmLtj ppZkwCUKUPSKE4fMS/XgprlV7FKNqg== =/0VE -----END PGP SIGNATURE----- --i32q7qdkfydayaoi--