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 C99C9C91 for ; Sun, 20 Dec 2015 11:25:03 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail149113.authsmtp.com (outmail149113.authsmtp.com [62.13.149.113]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id A4BC9A0 for ; Sun, 20 Dec 2015 11:25:02 +0000 (UTC) Received: from mail-c232.authsmtp.com (mail-c232.authsmtp.com [62.13.128.232]) by punt21.authsmtp.com (8.14.2/8.14.2/) with ESMTP id tBKBP1Kc081036; Sun, 20 Dec 2015 11:25:01 GMT Received: from muck ([24.114.39.101]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id tBKBOt1k075970 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Sun, 20 Dec 2015 11:24:59 GMT Date: Sun, 20 Dec 2015 03:24:54 -0800 From: Peter Todd To: Gregory Maxwell Message-ID: <20151220112454.GB16187@muck> References: <50e629572d8de852eb789d50b34da308@xbt.hk> <1449961269.2210.5.camel@yahoo.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="TakKZr9L6Hm6aLOc" Content-Disposition: inline In-Reply-To: X-Server-Quench: 4ee93efb-a70c-11e5-829e-00151795d556 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdAIUHFAXAgsB AmMbWlVeUlh7WWI7 aQ5PbARZfElHQQRq UVdMSlVNFUssc2dz eVofCRl1cgxBeDBx Z0RjWD5fCRFzdhMr EFMFEm1VeGZhPWUC WEJRIh5UcAJPfxhM bwR6UXVDAzANdhEy HhM4ODE3eDlSNhEd bAYXIl8OCUoMBDs1 QQxKIAkfOlZNWCQv Lxs7NhYXG0AfM145 OEcgX11QOR4OAQpf GSkA X-Authentic-SMTP: 61633532353630.1037:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 24.114.39.101/587 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] Forget dormant UTXOs without confiscating bitcoin X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 20 Dec 2015 11:25:03 -0000 --TakKZr9L6Hm6aLOc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Dec 13, 2015 at 02:07:36AM +0000, Gregory Maxwell via bitcoin-dev w= rote: > On Sun, Dec 13, 2015 at 1:00 AM, Vincent Truong via bitcoin-dev > wrote: > > have run a node/kept their utxo before they were aware of this change a= nd > > then realise miners have discarded their utxo. Oops? >=20 > I believe you have misunderstood jl2012's post. His post does not > cause the outputs to become discarded. They are still spendable, > but the transactions must carry a membership proof to spend them. > They don't have to have stored the data themselves, but they must > get it from somewhere-- including archive nodes that serve this > purpose rather than having every full node carry all that data forever. >=20 > Please be conservative with the send button. The list loses its > utility if every moderately complex idea is hit with reflexive > opposition by people who don't understand it. >=20 > Peter Todd has proposed something fairly similar with "STXO > commitments". The primary argument against this kind of approach that That's incorrect terminology - what I proposed are "TXO commitments". I proposed that a MMR of all prior transaction outputs's, spent and unspent, be committed too in blocks along with a spentness flag, not just spent transaction outputs. That's why I often use the term (U)TXO commitments to refer to both classes of proposals. > I'm aware of is that the membership proofs get pretty big, and if too > aggressive this trades bandwidth for storage, and storage is usually > the cheaper resource. Though at least the membership proofs could be > omitted when transmitting to a node which has signaled that it has > kept the historical data anyways. What I proprosed is that a consensus-critical maximum UTXO age be part of the protocol; UTXO's younger than that age are expected to be cached. For UTXO's older than that age, they can be dropped from the cache, however to spend them you are required to provide the proof, and that proof counts as blockchain space to account for the fact that they do need to be broadcast on the network. The proofs are relatively large, but not so much larger than a CTxIn as to make paying for that data infeasible. --=20 'peter'[:-1]@petertodd.org 00000000000000000188b6321da7feae60d74c7b0becbdab3b1a0bd57f10947d --TakKZr9L6Hm6aLOc Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQGrBAEBCACVBQJWdpADXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAwMTg4YjYzMjFkYTdmZWFlNjBkNzRjN2IwYmVjYmRhYjNi MWEwYmQ1N2YxMDk0N2QvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQwIXyHOf0udwGfgf/WXdUHH9qmA4l0duFhJejHs8S KizDR7bCrjlXCNoY1UwX6Hj8GYFH3Y2Wx/kxGGQobEaPIWF3li7eXER1fC4f+ndo h2oYIDCAjOrzaJ64GDaosk9DN2z9i+SsJgDY+akWTdy4Lef0TVrBPxCg3+6EANZf kY8hQlqr/t0wu2L4ahlXbYdarn2eUA34bUEUw1w4emhYlUQAL/8IvVGfjCrq/eLk wCcdzZ7BhN07wGV/bZLdDvaAxgWOpXBRxsr7ot6wBrk+Uirrah1wOddZuxUwWcqw weDBEMoayiTzWyAzc6zmpDbgc8bt/3mPH5AgF88AdSnRavCIffbIZ//n4tDGrA== =J/FO -----END PGP SIGNATURE----- --TakKZr9L6Hm6aLOc--