From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id E4162C0175; Wed, 22 Apr 2020 18:25:36 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id DCF67204A0; Wed, 22 Apr 2020 18:25:36 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id TZ3rUZv8oUsb; Wed, 22 Apr 2020 18:25:36 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from newmail.dtrt.org (li1228-87.members.linode.com [45.79.129.87]) by silver.osuosl.org (Postfix) with ESMTPS id 22E6920438; Wed, 22 Apr 2020 18:25:35 +0000 (UTC) Received: from harding by newmail.dtrt.org with local (Exim 4.92) (envelope-from ) id 1jRK3v-0004gW-T7; Wed, 22 Apr 2020 14:25:31 -0400 Date: Wed, 22 Apr 2020 14:24:54 -0400 From: "David A. Harding" To: Matt Corallo Message-ID: <20200422182454.3y3foxxhiovokovp@ganymede> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="hri62yla7f2etgkz" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 Cc: Bitcoin Protocol Discussion , lightning-dev Subject: Re: [bitcoin-dev] RBF Pinning with Counterparties and Competing Interest X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Apr 2020 18:25:37 -0000 --hri62yla7f2etgkz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Apr 20, 2020 at 10:43:14PM -0400, Matt Corallo via Lightning-dev wrote: > A lightning counterparty (C, who received the HTLC from B, who > received it from A) today could, if B broadcasts the commitment > transaction, spend an HTLC using the preimage with a low-fee, > RBF-disabled transaction. After a few blocks, A could claim the HTLC > from B via the timeout mechanism, and then after a few days, C could > get the HTLC-claiming transaction mined via some out-of-band agreement > with a small miner. This leaves B short the HTLC value. IIUC, the main problem is honest Bob will broadcast a transaction without realizing it conflicts with a pinned transaction that's already in most node's mempools. If Bob knew about the pinned transaction and could get a copy of it, he'd be fine. In that case, would it be worth re-implementing something like a BIP61 reject message but with an extension that returns the txids of any conflicts? For example, when Bob connects to a bunch of Bitcoin nodes and sends his conflicting transaction, the nodes would reply with something like "rejected: code 123: conflicts with txid 0123...cdef". Bob could then reply with a a getdata('tx', '0123...cdef') to get the pinned transaction, parse out its preimage, and resolve the HTLC. This approach isn't perfect (if it even makes sense at all---I could be misunderstanding the problem) because one of the problems that caused BIP61 to be disabled in Bitcoin Core was its unreliability, but I think if Bob had at least one honest peer that had the pinned transaction in its mempool and which implemented reject-with-conflicting-txid, Bob might be ok. -Dave --hri62yla7f2etgkz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEgxUkqkMp0LnoXjCr2dtBqWwiadMFAl6gi/YACgkQ2dtBqWwi adOvUQ/9EgDa7RVIjNhX/NGa4FiAmV+DQbG0FQXoafFPQmPp1ZW6/FITH1yqZtot n+LsaVaN3Xq8CWFS9M/Hh66ryqdcf+QHxxAk1o1AO7I1zIMK5k+sMen2inPynCZW FzHduDYW2IUUpAWKYPEx6AG8J+luRp9M2ccm0AjiNNADX7ZU6z9CLc0MoCMLTD3U 2b2Xxx5PWIetMHSjBunk8LNo8nBcCecqg3svZsjOdcGxVmhyPAIlswLVFiTArydB hqueJdSyMmbFHQGUMINbgEXKOiibU/sgYOxc1Q3xr1D9cmO7BqbkfwRxwRBtzCzD 6VfiLkwcMr0D18ci5WwY/xqPRqJX2xsbmZFRgXlLpGGnFQiHNS/FmiJyszhWvN8x RucX0LmiKIK5m/AzjwtI+Crf9e4PGXKCsCPsuv2z8iYAZ65qidgrFWnpS/+moWbz f7qhZsnA757wR3K1PtjMgRl6C3AJJlu1Gb82svw2/l1HL7/LBaVMMn7Hwznrk1iq iCtk/xoMKDDWx169Eu5Va7mXg1yDeRjK/5q/UKEp2eAQP9mrHIuOK9SGxz9v4nWn sr9Fsm+MVXcCTFE14jfVZL8F0A/A44aKFMRAIYH1p7pXOisagGj0m8CtqlAXB4nA iuaos90C9QsyeobC4IYqtj7qFpUxEuHcTiEqY61emcCs6m+o+m8= =tXJQ -----END PGP SIGNATURE----- --hri62yla7f2etgkz--