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[66.111.4.25]) by gmr-mx.google.com with ESMTPS id b8-20020a05620a118800b00789d9871717si848899qkk.5.2024.03.19.07.24.50 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Mar 2024 07:24:50 -0700 (PDT) Received-SPF: pass (google.com: domain of pete@petertodd.org designates 66.111.4.25 as permitted sender) client-ip=66.111.4.25; Received: from compute7.internal (compute7.nyi.internal [10.202.2.48]) by mailout.nyi.internal (Postfix) with ESMTP id 71EA35C0072; Tue, 19 Mar 2024 10:24:50 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute7.internal (MEProxy); Tue, 19 Mar 2024 10:24:50 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvledrledtgdefkecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpeffhffvvefukfhfgggtuggjsehgtderredttdejnecuhfhrohhmpefrvghtvghr ucfvohguugcuoehpvghtvgesphgvthgvrhhtohguugdrohhrgheqnecuggftrfgrthhtvg hrnhepgfelvdegveejfffghfeugeffleetvdduleduvdfgudekgfffudefgefgfeekkeej necuffhomhgrihhnpehgihhthhhusgdrtghomhdpphgvthgvrhhtohguugdrohhrghenuc evlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehpvghtvges phgvthgvrhhtohguugdrohhrgh X-ME-Proxy: Feedback-ID: i525146e8:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 19 Mar 2024 10:24:49 -0400 (EDT) Received: by localhost (Postfix, from userid 1000) id 1C4AC5F84B; Tue, 19 Mar 2024 14:24:46 +0000 (UTC) Date: Tue, 19 Mar 2024 14:24:46 +0000 From: Peter Todd To: Martin =?utf-8?Q?Habov=C5=A1tiak?= Cc: bitcoindev@googlegroups.com Subject: Re: [bitcoindev] Anyone can boost - a more efficient alternative to anchor outputs Message-ID: References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="h6eixIpcyZQz10r2" Content-Disposition: inline In-Reply-To: X-Original-Sender: pete@petertodd.org X-Original-Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@messagingengine.com header.s=fm2 header.b=J8rjfdJE; spf=pass (google.com: domain of pete@petertodd.org designates 66.111.4.25 as permitted sender) smtp.mailfrom=pete@petertodd.org Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -0.8 (/) --h6eixIpcyZQz10r2 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 19, 2024 at 10:47:26AM +0100, Martin Habov=C5=A1tiak wrote: > Hello everyone, >=20 > For a while I was thinking that anchor outputs/CPFP are wasteful and I > believe I have finally found a better way of doing them. I wrote up a > document describing the solution here: > https://gist.github.com/Kixunil/6ae6f787db36d0d5ed3220f5bcece7f7 FYI I believe that Jeremy Rubin proposed essentially the same idea before o= n this mailing list, using the term "Transaction Sponsorship" to describe it. > At first sight this looks broken because of the pinning problem. > Today, if ANYONECANSPEND output is used an attacker could boost a > transaction of someone else in a way that would make it stuck in the > mempool. To be clear, this issue exists because we don't currently do replace-by-fee-rate with a reasonably low minimum fee-rate ratio. Correct me if I'm wrong, but I believe at the moment the only significant transaction pinning attack remaining for ANYONECANSPEND, spending confirmed outputs, is Rule #3 pinning. > This is because of policy rules protecting the network against DoS attack= s, > so apparently the rules cannot be relaxed. > The rules are designed specifically to impose cost on attackers. I disagree re: DoS attacks. We already have plenty of free-relay attacks. R= BFR does not significantly change that situation. RBFR is running live right now on Libre Relay nodes on mainnet. If these free-relay attacks were actually serious, I'd suggest that people demonstra= te them! > The reason why anyone can boost is not actually broken is that multiple > independent transactions can boost the same transaction. Note that introducing this mechanism with a soft-fork will also create enti= rely new smart contracting facilities, unrelated to boosting/sponsorship. For example, I believe that Ark could make use of this mechanism to more efficiently replace their connector output scheme. > Notably, such boosting service would *not* be trustless but non-delivery > could be easily proven using LN invoice and preimage. > Perhaps it is possible to make the service trustless but that's probably > not worth the effort given how low the amounts are. To reduce trust you could do an automated, multiple round, signing scheme w= here the service signs transations with higher and higher fee-rates in exchange = for most funds over LN. The minimum amount the sender would need to front would= be the cost of the additional ~32 bytes required. Though arranging this idea w= ith multiple people at once could be tricky. > ## Known downsides >=20 > ### This requires a soft fork >=20 > Soft forks can be contentious and difficult to deploy. I'd suggest you find other use-cases for this mechanism, eg Ark, and presen= t it as a solution to a bunch of problems at once. I'm not sure that the fee pay= ment alone is sufficient incentive. You don't mention it below. But another downside is you provide an easy way= for arbitrary third parties to get a particular transaction mined. I raised thi= s issue the last time it was discussed on this list, giving the example of my OpenTimestamps calendars: it would be annoying if people could easily get out-of-date timestamp txs mined by just paying a bit of money. While this i= s always *possible*, implementing a mechanism that makes doing this easy has downsides. On balance though, if it enables things like Ark, you'll help ma= ke the argument that the upsides are worth it. --=20 https://petertodd.org 'peter'[:-1]@petertodd.org --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to bitcoindev+unsubscribe@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/= bitcoindev/ZfmgLhETBEDql85w%40petertodd.org. --h6eixIpcyZQz10r2 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE0RcYcKRzsEwFZ3N5Lly11TVRLzcFAmX5oCwACgkQLly11TVR Lzfqkw//TWUnJK8/YYgI5Fa+/+8jLF/4TsKKLHOD5mEWb3xBenBVHGJyV4hCiv/S faQiH5qiQLXAAaTuQm4gYifJ/IXXbgAbpGfU6YnlqsyM95kDjb0MZjeqNcrkDN72 jluiaitFZv7IFQ/5EFwBrqE1FjMgUd3a7U8xXKiVFqKnufSWUxnVPlqd7fB/tZV6 cf66Ww/MmUtVHIZ1K6GF39FHDkhhbH0PM/gIo6LYKLPQqhCe8Ik6FgRYfleQHMOV DjvNJ1z3rPGlPffZHbCyG1I2zXt9zEDpHNRXA+a1oboafIEZqcHItLN3lsvoCp5i F6kuK1Vvgw1q3jfng5fCWVeCSaWoa5sKgXHBSJf98OWpQIPk3JBX4LP+VEebW9Al 1wOQ/AeJjILYYLkDecl7rizrLSgCNh+sY97QSnGyZgAWqs+NsIOGNjlLFacpoMXT ZoAvVidHBBNthea+WzXM98e2St0tAkt6lX/L9Ndwr78CJL/UUZcs4LWtPgALDRPg pZgUtnyd2cfrdWj3t+U5WumWRj3xkzrF7vPwRS8Yk6jfUmx5FnycRYzLt/CZGn6T 7NtlQHaZ3twO8I+HgSQEPmDOZ5r/Ui5u2xHQVXirgcWKtUMsM7g7x/sNpwMA/CTR KYtHdMmI/IWj/q/zTC9rtO+vsZgnk11r9HV52S2QvOVfcleI+vI= =QwdO -----END PGP SIGNATURE----- --h6eixIpcyZQz10r2--