From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 038A3C016E; Fri, 19 Jun 2020 20:53:32 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id DFE1888E29; Fri, 19 Jun 2020 20:53:32 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YUuddqKVlVaj; Fri, 19 Jun 2020 20:53:32 +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 whitealder.osuosl.org (Postfix) with ESMTPS id 4A6BA88DFA; Fri, 19 Jun 2020 20:53:32 +0000 (UTC) Received: from harding by newmail.dtrt.org with local (Exim 4.92) (envelope-from ) id 1jmO0x-0004fT-Gw; Fri, 19 Jun 2020 16:53:31 -0400 Date: Fri, 19 Jun 2020 16:52:20 -0400 From: "David A. Harding" To: Bitcoin Protocol Discussion Message-ID: <20200619205220.fshbr7pbijaerbf2@ganymede> References: <67334082-5ABA-45C7-9C09-FF19B119C80D@mattcorallo.com> <62P_3wvv8z7AVCdKPfh-bs30-LliHkx9GI9Og3wqIK6hadIG0d6MJJm077zac1erpPUy31FqgZjkAjEl9AQtrOCg4XA5cxozBb7-OIbbgvE=@protonmail.com> <4c4f3a06-0078-ef6a-7b06-7484f0f9edf1@mattcorallo.com> <20200619195846.fclw4ilngvbbf2kk@ganymede> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ob7sr5hwmygd7js6" Content-Disposition: inline In-Reply-To: <20200619195846.fclw4ilngvbbf2kk@ganymede> User-Agent: NeoMutt/20180716 Cc: lightning-dev Subject: Re: [bitcoin-dev] [Lightning-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: Fri, 19 Jun 2020 20:53:34 -0000 --ob7sr5hwmygd7js6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jun 19, 2020 at 03:58:46PM -0400, David A. Harding via bitcoin-dev = wrote: > I think you're assuming here that the attacker broadcast a particular > state. =20 Whoops, I managed to confuse myself despite looking at Bastien's excellent explainer. The attacker would be broadcasting the latest state, so the honest counterparty would only need to send one blind child. However, the blind child will only be relayed by a Bitcoin peer if the peer also has the parent transaction (the latest state) and, if it has the parent transaction, you should be able to just getdata('tx', $txid) that transaction from the peer without CPFPing anything. That will give you the preimage and so you can immediately resolve the HTLC with the upstream channel. Revising my conclusion from the previous post: I think the strongman argument for the attack would be that the attacker will be able to perform a targeted relay of the low-feerate preimage-containing transaction to just miners---everyone else on the network will receive the honest user's higher-feerate expired-timelock transaction. Unless the honest user happens to have a connection to a miner's node, the user will neither be able to CPFP fee bump nor use getdata to retrieve the preimage. Sorry for the confusion. -Dave --ob7sr5hwmygd7js6 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEgxUkqkMp0LnoXjCr2dtBqWwiadMFAl7tJYQACgkQ2dtBqWwi adNYDxAAjEpMvcl6egrIYvc78PnClCsKl6RlmPe+/he0keX/gzkomcBYe+48QI2I CaRpSCrUIjIzLvCjd81gZqp8XZ56qPT2YNtFPT9UdWpZGSirmy9T/BM/WHYEa1Ca Ve0w/z3EysCF2fPiAH7k9m9uXPvTMBNhubS7/ypgfr8DbHn+zs/+ZyBMdVY/f4Jh bj9aYGhK2XpmozNGhdx7Cf+FCMN+vLjWACzE+yk2XTLQdgyBPIusjt4rQhIqByz/ TC9OWdUVIYeDK0e45/Pe4fGt3irK5fOcNhR8RZChQS/N1W/vHJdMfQxi6GqNBQDN ruAoTd0fGGUI0friLCAj6Wdz54ERvnegb4u5QNVahHpggh4By5jQozc869tKD7Z/ gjLVhMC5esFfXz6dxwprUXrPzmaKg3eV6a3Z0TKr8DWy9lUeKd6/Ijuiv6MNOX8l LAPUp1kDYW/Ex052WS0B2nreOUpEJ8n++3TnhZhWfmYWE/cgIJfg6iTqYYquYp2e ns/vIyP/gBluE0ckjsd9khqask5I6GlEUNRBvzIEqIDvKcZ+DEdEcUWmM+JMTBgd hylm8LtQCla8bv2IZhAcq+qNkBPvEMw2B/oFFCgF8+q3frZPhxV7P76u4VDmDO6W CqhP7b4slE9yjcBbNjaznJye1nVUODYjPA1bJWeqDL20HkLsjn0= =iFyQ -----END PGP SIGNATURE----- --ob7sr5hwmygd7js6--