Return-Path: Received: from smtp1.osuosl.org (smtp1.osuosl.org [IPv6:2605:bc80:3010::138]) by lists.linuxfoundation.org (Postfix) with ESMTP id EFFCDC002D for ; Wed, 19 Oct 2022 16:08:35 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id BD87F81383 for ; Wed, 19 Oct 2022 16:08:35 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org BD87F81383 Authentication-Results: smtp1.osuosl.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20210112 header.b=WxcsY0KY X-Virus-Scanned: amavisd-new at osuosl.org X-Spam-Flag: NO X-Spam-Score: -1.838 X-Spam-Level: X-Spam-Status: No, score=-1.838 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_KAM_HTML_FONT_INVALID=0.01] autolearn=ham autolearn_force=no Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id WNJxroP1Oweb for ; Wed, 19 Oct 2022 16:08:34 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 9AED281320 Received: from mail-ej1-x632.google.com (mail-ej1-x632.google.com [IPv6:2a00:1450:4864:20::632]) by smtp1.osuosl.org (Postfix) with ESMTPS id 9AED281320 for ; Wed, 19 Oct 2022 16:08:33 +0000 (UTC) Received: by mail-ej1-x632.google.com with SMTP id a26so40736952ejc.4 for ; Wed, 19 Oct 2022 09:08:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=X1fA54JziOb/IpUj78xPMzXQeeuZcRUqQcZTbdzyivo=; b=WxcsY0KYj7gDfqj2YSm15VI3dT9y1TQ8SX9dyecQ++EUrD1NCnER488lwzKvcWAteE LLss/vEbpLKPikEkq6G8sXHQ2998p80RNB8/fkZzmvUveFeGfDS1Z96rdmwd+Oeabe0k 6D0S5kmvqbPxpB7/wj0fmUaxaTrFKsY/8fBqtn3WpZIeanfKUlN4csu4tgiYxjp+WgLu KTerMnmF7zucELaU2PRtzAIOWN6XK2VKQeKaHeM+fEyKOF09qbLK3ts029vaT/iq+yJR sAdD7r6ozVjDSdh1vW9HiJoRE2vv/Zw2ykncyAy2SVnTDaK4npefcPb5OwU5VPG9OkeD RUtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=X1fA54JziOb/IpUj78xPMzXQeeuZcRUqQcZTbdzyivo=; b=BppJi+1M7jwQtlwp4AHjXeOqJXyRPU6Jq4kqcWS9Efx5dn4XNzCfUgADS8NIGIDHrN MNeES+YdJ61sOAF/W1ZRUlTjnZN1a/Ip4INf9rPcT1zObJqBOFj/W1k+lrP+aUZb6T6M pCnCBorBWIGBVZRVs9pTipH9h8lqfZbic1r+KUlOa8xScZa+UBZRki6fi8NV1rP/MscT Pb5S+UcP69yNyhjO1Nqi8RYVjPfX+pR/5tqMZiLR2LCeXT4ANcqPdxEbNjJUlNiDLZcU s5yXEWvRXQu6SIHr0ZPTo+3bDCSC/7jJbQCqBV1mmWnLVVBRWEdALrtR3VS8qBDbvnBf 3EFA== X-Gm-Message-State: ACrzQf3ftHRxHnq8RkN3zJMQlvDVn9gREvEbbGdvVohexr4LPgtdEZJT IIGSg7hky6BvId3jREPBXs1avcx0MLXuFOaPPIYASttf X-Google-Smtp-Source: AMsMyM7RXJKoXnfS5F46NbDcgiXOCNU60kxRTW3bIJytrIR2ZOLMDBwTo+DNRlj1+hwQfUieSlICI0MMzTjDwPjPfWs= X-Received: by 2002:a17:906:d54d:b0:78e:f130:7099 with SMTP id cr13-20020a170906d54d00b0078ef1307099mr7604848ejc.142.1666195711588; Wed, 19 Oct 2022 09:08:31 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Greg Sanders Date: Wed, 19 Oct 2022 12:08:19 -0400 Message-ID: To: Sergej Kotliar , Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary="00000000000084003805eb656b91" Subject: Re: [bitcoin-dev] [Opt-in full-RBF] Zero-conf apps in immediate danger 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, 19 Oct 2022 16:08:36 -0000 --00000000000084003805eb656b91 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Another downside is that the sender may not opt into a non-pinnable future format like "V3 transactions", making CPFP difficult. They may spend a lot of fees to do this however, so maybe we're really reaching here. On Wed, Oct 19, 2022 at 12:07 PM Sergej Kotliar via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > It's an interesting idea, presumably it would work w the new package rela= y. > Scorched earth bidding war is definitely fine to deter this type of abuse= . > Need to consider it more thoroughly from all sides tho. CPFP on the serve= r > side generally has a couple of downsides: > * Requires a hot wallet to receive bitcoin > * an entity that is reliably known to do CPFP can be abused by people > looking to consolidate utxos, which can be quite costly. Might be solvabl= e > with a set of conditionals, and bad UX for abusers is less of a concern := ) > > Will follow up after more deliberation, thanks! > > > On Wed, 19 Oct 2022 at 17:43, Jeremy Rubin > wrote: > >> If they do this to you, and the delta is substantial, can't you sweep al= l >> such abusers with a cpfp transaction replacing their package and giving = you >> the original txn? >> >> On Wed, Oct 19, 2022, 7:33 AM Sergej Kotliar via bitcoin-dev < >> bitcoin-dev@lists.linuxfoundation.org> wrote: >> >>> Hi all, >>> >>> Chiming in on this thread as I feel like the real dangers of RBF as >>> default policy aren't sufficiently elaborated here. It's not only about= the >>> zero-conf (I'll get to that) but there is an even bigger danger called = the >>> american call option, which risks endangering the entirety of BIP21 "Sc= an >>> this QR code with your wallet to buy this product" model that I believe >>> we've all come to appreciate. Specifically, in a scenario with high >>> volatility and many transactions in the mempools (which is where RBF wo= uld >>> come in handy), a user can make a low-fee transaction and then wait for >>> hours, days or even longer, and see whether BTCUSD moves. If BTCUSD mov= es >>> up, user can cancel his transaction and make a new - cheaper one. The >>> biggest risk in accepting bitcoin payments is in fact not zeroconf risk >>> (it's actually quite easily managed), it's FX risk as the merchant must >>> commit to a certain BTCUSD rate ahead of time for a purchase. Over time >>> some transactions lose money to FX and others earn money - that evens o= ut >>> in the end. But if there is an _easily accessible in the wallet_ featur= e to >>> "cancel transaction" that means it will eventually get systematically >>> abused. A risk of X% loss on many payments that's easy to systematicall= y >>> abuse is more scary than a rare risk of losing 100% of one occasional >>> payment. It's already possible to execute this form of abuse with opt-i= n >>> RBF, which may lead to us at some point refusing those payments (even w= ith >>> confirmation) or cumbersome UX to work around it, such as crediting the >>> bitcoin to a custodial account. >>> >>> To compare zeroconf risk with FX risk: I think we've had one incident i= n >>> 8 years of operation where a user successfully fooled our server to acc= ept >>> a payment that in the end didn't confirm. To successfully fool (non-RBF= ) >>> zeroconf one needs to have access to mining infrastructure and probabil= ity >>> of success is the % of hash rate controlled. This is simply due to the = fact >>> that the network currently won't propagage the replacement transaction = to >>> the miner, which is what's being discussed here. American call option r= isk >>> would however be available to 100% of all users, needs nothing beyond t= he >>> wallet app, and has no cost to the user - only upside. >>> >>> Bitrefill currently processes 1500-2000 onchain payments every day. For >>> us, a world where bitcoin becomes de facto RBF by default, means that w= e >>> would likely turn off the BIP21 model for onchain payments, instruct >>> Bitcoin users to use Lightning or deposit onchain BTC to a custodial >>> account that we have. >>> This option is however not available for your typical >>> BTCPayServer/CoinGate/Bitpay/IBEX/OpenNode et al. Would be great to hea= r >>> from other merchants or payment providers how they see this new behavio= r >>> and how they would counteract it. >>> >>> Currently Lightning is somewhere around 15% of our total bitcoin >>> payments. This is very much not nothing, and all of us here want Lightn= ing >>> to grow, but I think it warrants a serious discussion on whether we wan= t >>> Lightning adoption to go to 100% by means of disabling on-chain commerc= e. >>> For me personally it would be an easier discussion to have when Lightni= ng >>> is at 80%+ of all bitcoin transactions. Currently far too many bitcoin >>> users simply don't have access to Lightning, and of those that do and h= old >>> their own keys Muun is the biggest wallet per our data, not least due t= o >>> their ease-of-use which is under threat per the OP. It's hard to assess= how >>> many users would switch to Lightning in such a scenario, the communicat= ion >>> around it would be hard. My intuition says that the majority of the cur= rent >>> 85% of bitcoin users that pay onchain would just not use bitcoin anymor= e, >>> probably shift to an alt. The benefits of Lightning are many and obviou= s, >>> we don't need to limit onchain to make Lightning more appealing. As an >>> anecdote, we did experiment with defaulting to bech32 addresses some ye= ars >>> back. The result was that simply users of the wallets that weren't able= to >>> pay to bech32 didn't complete the purchase, no support ticket or anythi= ng, >>> just "it didn't work =F0=9F=A4=B7=E2=80=8D=E2=99=82=EF=B8=8F" and user = moved on. We rolled it back, and later >>> implemented a wallet selector to allow modern wallets to pay to bech32 >>> while other wallets can pay to P2SH. This type of thing is clunky, and >>> requires a certain level of scale to be able to do, we certainly wouldn= 't >>> have had the manpower for that when we were starting out. This why I'm >>> cautious about introducing more such clunkiness vectors as they are >>> centralizing factors. >>> >>> I'm well aware of the reason for this policy being suggested and the >>> potential pinning attack vector for LN and other smart contracts, but I >>> think these two risks/costs need to be weighed against eachother first = and >>> thoroughly discussed because the costs are non-trivial on both sides. >>> >>> Sidenote: On the efficacy of RBF to "unstuck" stuck transactions >>> After interacting with users during high-fee periods I've come to not >>> appreciate RBF as a solution to that issue. Most users (80% or so) simp= ly >>> don't have access to that functionality, because their wallet doesn't >>> support it, or they use a custodial (exchange) wallet etc. Of those tha= t >>> have the feature - only the power users understand how RBF works, and >>> explaining how to do RBF to a non-power-user is just too complex, for t= he >>> same reason why it's complex for wallets to make sensible non-power-use= r UI >>> around it. Current equilibrium is that mostly only power users have acc= ess >>> to RBF and they know how to handle it, so things are somewhat working. = But >>> rolling this out to the broad market is something else and would likely >>> cause more confusion. >>> CPFP is somewhat more viable but also not perfect as it would require >>> lots of edge case code to handle abuse vectors: What if users abuse a >>> generous CPFP policy to unstuck past transactions or consolidate large >>> wallets. Best is for CPFP to be done on the wallet side, not the mercha= nt >>> side, but there too are the same UX issues as with RBF. >>> In the end a risk-based approach to decide on which payments are >>> non-trivial to reverse is the easiest, taking account user experience a= nd >>> such. Remember that in the fiat world card payments have up to 5% >>> chargebacks, whereas we in zero-conf bitcoin land we deal with "fewer t= han >>> 1 in a million" accepted transactions successfully reversed. These days= we >>> have very few support issues related to bitcoin payments. The few that = do >>> come in are due to accidental RBF users venting frustration about waiti= ng >>> for their tx to confirm. >>> "In theory, theory and practice are the same. In practice, they are not= " >>> >>> All the best, >>> Sergej Kotliar >>> CEO Bitrefill.com >>> >>> >>> -- >>> >>> Sergej Kotliar >>> >>> CEO >>> >>> >>> Twitter: @ziggamon >>> >>> >>> www.bitrefill.com >>> >>> Twitter | Blog >>> | Angellist >>> >>> >>> >>> -- >>> >>> Sergej Kotliar >>> >>> CEO >>> >>> >>> Twitter: @ziggamon >>> >>> >>> www.bitrefill.com >>> >>> Twitter | Blog >>> | Angellist >>> >>> _______________________________________________ >>> bitcoin-dev mailing list >>> bitcoin-dev@lists.linuxfoundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>> >> > > -- > > Sergej Kotliar > > CEO > > > Twitter: @ziggamon > > > www.bitrefill.com > > Twitter | Blog > | Angellist > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --00000000000084003805eb656b91 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Another=C2=A0downside is that the sender may not opt into = a non-pinnable future format like "V3 transactions", making CPFP = difficult. They may spend a lot of fees to do this however, so maybe we'= ;re really reaching here.

On Wed, Oct 19, 2022 at 12:07 PM Sergej Kotliar vi= a bitcoin-dev <= bitcoin-dev@lists.linuxfoundation.org> wrote:
It's an interesti= ng idea, presumably it would work w the new package relay.
Scorched ear= th bidding war is definitely fine to deter this type of abuse.
Ne= ed to consider it more thoroughly from all sides tho. CPFP on the server si= de generally has a couple of downsides:
* Requires a hot wallet t= o receive bitcoin
* an entity that is reliably known to do CPFP c= an be abused by people looking to consolidate utxos, which can be quite cos= tly. Might be solvable with a set of conditionals, and bad UX for abusers i= s less of a concern :)

Will follow up after more d= eliberation,=C2=A0thanks!


On Wed, 19 Oct 2022 at 17:43,= Jeremy Rubin <jeremy.l.rubin@gmail.com> wrote:
If they do this to you, and = the delta is substantial, can't you sweep all such abusers with a cpfp = transaction replacing their package and giving you the original txn?
<= br>
On Wed,= Oct 19, 2022, 7:33 AM Sergej Kotliar via bitcoin-dev <bitcoin-dev@lists= .linuxfoundation.org> wrote:
Hi all,

Chiming in on this thread as I feel like t= he real dangers of RBF as default policy aren't sufficiently elaborated= here. It's not only about the zero-conf (I'll get to that) but the= re is an even bigger danger called the american call option, which risks en= dangering the entirety of BIP21 "Scan this QR code with your wallet to= buy this product" model that I believe we've all come to apprecia= te. Specifically, in a scenario with high volatility and many transactions = in the mempools (which is where RBF would come in handy), a user can make a= low-fee transaction and then wait for hours, days or even longer, and see = whether BTCUSD moves. If BTCUSD moves up, user can cancel his transaction a= nd make a new - cheaper one. The biggest risk in accepting bitcoin payments= is in fact not zeroconf risk (it's actually quite easily managed), it&= #39;s FX risk as the merchant must commit to a certain BTCUSD rate ahead of= time for a purchase. Over time some transactions lose money to FX and othe= rs earn money - that evens out in the end. But if there is an _easily acces= sible in the wallet_ feature to "cancel transaction" that means i= t will eventually get systematically abused. A risk of X% loss on many paym= ents that's easy to systematically abuse is more scary than a rare risk= of losing 100% of one occasional payment. It's already possible to exe= cute this form of abuse with opt-in RBF, which may lead to us at some point= refusing those payments (even with confirmation) or cumbersome UX to work = around it, such as crediting the bitcoin to a custodial account.
=
To compare zeroconf risk with FX risk: I think we've had= one incident in 8 years of operation where a user successfully fooled our = server to accept a payment that in the end didn't confirm. To successfu= lly fool (non-RBF) zeroconf one needs to have access to mining infrastructu= re and probability of success is the % of hash rate controlled. This is sim= ply due to the fact that the network currently won't propagage the repl= acement transaction to the miner, which is what's being discussed here.= American call option risk would however be available to 100% of all users,= needs nothing beyond the wallet app, and has no cost to the user - only up= side.

Bitrefill currently processes 1500-2000 = onchain payments every day. For us, a world where bitcoin becomes de facto = RBF by default, means that we would likely turn off the BIP21 model for onc= hain payments, instruct Bitcoin users to use Lightning or deposit onchain B= TC to a custodial account that we have.=C2=A0
This option is = however not available for your typical BTCPayServer/CoinGate/Bitpay/IBEX/Op= enNode et al. Would be great to hear from other merchants or payment provid= ers how they see this new behavior and how they would counteract it.
<= div>
Currently Lightning is somewhere around 15% of our total= bitcoin payments. This is very much not nothing, and all of us here want L= ightning to grow, but I think it warrants a serious discussion on whether w= e want Lightning adoption to go to 100% by means of disabling on-chain comm= erce. For me personally it would be an easier discussion to have when Light= ning is at 80%+ of all bitcoin transactions. Currently far too many bitcoin= users simply don't have access to Lightning, and of those that do and = hold their own keys Muun is the biggest wallet per our data, not least due = to their ease-of-use which is under threat per the OP. It's hard to ass= ess how many users would switch to Lightning in such a scenario, the commun= ication around it would be hard. My intuition says that the majority of the= current 85% of bitcoin users that pay onchain would just not use bitcoin a= nymore, probably shift to an alt. The benefits of Lightning are many and ob= vious, we don't need to limit onchain to make Lightning more appealing.= As an anecdote, we did experiment with defaulting to bech32 addresses some= years back. The result was that simply users of the wallets that weren'= ;t able to pay to bech32 didn't complete the purchase, no support ticke= t or anything, just "it didn't work =F0=9F=A4=B7=E2=80=8D=E2=99=82= =EF=B8=8F" and user moved on. We rolled it back, and later implemented= a wallet selector to allow modern wallets to pay to bech32 while other wal= lets can pay to P2SH. This type of thing=C2=A0 is clunky, and requires a ce= rtain level of scale to be able to do, we certainly wouldn't have had t= he manpower for that when we were starting out. This why I'm cautious a= bout introducing more such clunkiness vectors as they are centralizing fact= ors.

I'm well aware of the reason for this pol= icy being suggested and the potential pinning attack vector for LN and othe= r smart contracts, but I think these two risks/costs need to be weighed aga= inst eachother first and thoroughly discussed because the costs are non-tri= vial on both sides.

Sidenote: On the e= fficacy of RBF to "unstuck" stuck transactions
After in= teracting with users during high-fee periods I've come to not appreciat= e RBF as a solution to that issue. Most users (80% or so) simply don't = have access to that functionality, because their wallet doesn't support= it, or they use a custodial (exchange) wallet etc. Of those that have the = feature - only the power users understand how RBF works, and explaining how= to do RBF to a non-power-user is just too complex, for the same reason why= it's complex for wallets to make sensible non-power-user UI around it.= Current equilibrium is that mostly only power users have access to RBF and= they know how to handle it, so things are somewhat working. But rolling th= is out to the broad market is something else and would likely cause more co= nfusion.=C2=A0
CPFP is somewhat more viable but also not perfect = as it would require lots of edge case code to handle abuse vectors: What if= users abuse a generous CPFP policy to unstuck past transactions or consoli= date large wallets. Best is for CPFP to be done on the wallet side, not the= merchant side, but there too are the same UX issues as with RBF.=C2=A0
In the end a risk-based approach to decide on which payments are non= -trivial to reverse is the easiest, taking account user experience and such= . Remember that in the fiat world card payments have up to 5% chargebacks, = whereas we in zero-conf bitcoin land we deal with "fewer than 1 in a m= illion" accepted transactions successfully reversed. These days we hav= e very few support issues related to bitcoin payments. The few that do come= in are due to accidental RBF users venting frustration about waiting for t= heir tx to confirm.
"In theory, theory and practice are the = same. In practice, they are not"

All the best= ,=C2=A0
Sergej Kotliar
CEO Bitrefill.com

=

--

Sergej Kotliar

CEO=


Twitter: @ziggamon=C2=A0


www.bitrefill.com

Twitter | Blog | Angellist



--

= Sergej Kotliar

CEO


<= p dir=3D"ltr" style=3D"line-height:1.38;margin-top:0pt;margin-bottom:0pt"><= span style=3D"font-size:11pt;font-family:Arial;color:rgb(102,102,102);backg= round-color:transparent;font-weight:700;font-style:normal;font-variant:norm= al;text-decoration:none;vertical-align:baseline;white-space:pre-wrap">

Twitter: @ziggamon=C2=A0


www.= bitrefill.com

Twitter | Blog |= Angellist

_______________________________________________
bitcoin-dev mailing list
bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundati= on.org/mailman/listinfo/bitcoin-dev


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