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From: Greg Sanders <gsanders87@gmail.com>
Date: Wed, 2 Nov 2022 11:00:47 -0400
Message-ID: <CAB3F3DvbuawQwGou5mD_p814F6__0mdrKu1+fqXgAcP6iVOMOg@mail.gmail.com>
To: Peter Todd <pete@petertodd.org>
Content-Type: multipart/alternative; boundary="000000000000c0486805ec7e1bf6"
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Solving Multi-Party Flows Pinning with Opt-in
 Full-RBF Spent-nVersion Signaling
Precedence: list

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> ...and the attacker also pays out the nose if they're exploiting rule #3.

I agree the attacker puts more at stake in this case. If we're assuming
they pay the price and get mined, they can be booted from the protocol
whenever they get mined. I was speaking about the worst case scenario where
it's never mined.

> We shouldn't assume it will always exist.

Just making sure people know that today it does impact things today.

On Wed, Nov 2, 2022, 10:33 AM Peter Todd <pete@petertodd.org> wrote:

> On Wed, Nov 02, 2022 at 10:19:00AM -0400, Greg Sanders wrote:
> > Sorry, I forgot one point which is pertinent to this conversation.
> >
> > *Even with* fullrbf-everywhere and V3, pinning via rule#3 and rule#5 are
> > still an issue in coinjoin scenarios.
> >
> > Each coinjoin adversary can double-spend their coin to either full
> package
> > weight(101kvb),
> > or give 24 descendants, which means you quickly pay out the nose in
> rule#3
>
> ...and the attacker also pays out the nose if they're exploiting rule #3.
>
> > or are excluded
> > from RBFing it if you have 4+ greifers in your coinjoin violating rule#5.
> >
> > If we instead narrowed this policy to marking a transaction output as
> > opt-in to V3, it gets a bit more interesting. *Unfortunately,
> > double-spending counterparties can still cause rule#3 pain, one 100kvb
> > package of junk per peer,* but rule#5 violations is at least contained to
> > coinjoins with ~50 peers(assuming two transactions booted per input
> > double-spent, which would be the V3 max bumped per input).
>
> There's no hard technical reason for rule #5 to even exist. It's simply a
> conservative DoS limit to avoid having to do "too much" computation when
> processing a replacement in some replacement implementations. We shouldn't
> assume it will always exist. And like rule #3 pinning, exploiting it costs
> money.
>
> --
> https://petertodd.org 'peter'[:-1]@petertodd.org
>

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<div dir=3D"ltr"><div dir=3D"auto">&gt; ...and the attacker also pays out t=
he nose if they&#39;re exploiting rule #3.</div><div dir=3D"auto"><br></div=
><div dir=3D"auto">I agree the=C2=A0attacker puts more at stake in this cas=
e. If we&#39;re assuming they pay the price and get mined, they can be boot=
ed from the protocol whenever they get mined. I was speaking about the wors=
t case scenario where it&#39;s never mined.</div><div dir=3D"auto"><br></di=
v><div dir=3D"auto">&gt; We shouldn&#39;t assume it will always exist.</div=
><div dir=3D"auto"><br></div><div>Just making sure people know that today i=
t does impact things today.</div></div><br><div class=3D"gmail_quote"><div =
dir=3D"ltr" class=3D"gmail_attr">On Wed, Nov 2, 2022, 10:33 AM Peter Todd &=
lt;<a href=3D"mailto:pete@petertodd.org" target=3D"_blank">pete@petertodd.o=
rg</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margi=
n:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex=
">On Wed, Nov 02, 2022 at 10:19:00AM -0400, Greg Sanders wrote:<br>
&gt; Sorry, I forgot one point which is pertinent to this conversation.<br>
&gt; <br>
&gt; *Even with* fullrbf-everywhere and V3, pinning via rule#3 and rule#5 a=
re<br>
&gt; still an issue in coinjoin scenarios.<br>
&gt; <br>
&gt; Each coinjoin adversary can double-spend their coin to either full pac=
kage<br>
&gt; weight(101kvb),<br>
&gt; or give 24 descendants, which means you quickly pay out the nose in ru=
le#3<br>
<br>
...and the attacker also pays out the nose if they&#39;re exploiting rule #=
3.<br>
<br>
&gt; or are excluded<br>
&gt; from RBFing it if you have 4+ greifers in your coinjoin violating rule=
#5.<br>
&gt; <br>
&gt; If we instead narrowed this policy to marking a transaction output as<=
br>
&gt; opt-in to V3, it gets a bit more interesting. *Unfortunately,<br>
&gt; double-spending counterparties can still cause rule#3 pain, one 100kvb=
<br>
&gt; package of junk per peer,* but rule#5 violations is at least contained=
 to<br>
&gt; coinjoins with ~50 peers(assuming two transactions booted per input<br=
>
&gt; double-spent, which would be the V3 max bumped per input).<br>
<br>
There&#39;s no hard technical reason for rule #5 to even exist. It&#39;s si=
mply a<br>
conservative DoS limit to avoid having to do &quot;too much&quot; computati=
on when<br>
processing a replacement in some replacement implementations. We shouldn=
9;t<br>
assume it will always exist. And like rule #3 pinning, exploiting it costs<=
br>
money.<br>
<br>
-- <br>
<a href=3D"https://petertodd.org" rel=3D"noreferrer noreferrer" target=3D"_=
blank">https://petertodd.org</a> &#39;peter&#39;[:-1]@<a href=3D"http://pet=
ertodd.org" rel=3D"noreferrer noreferrer" target=3D"_blank">petertodd.org</=
a><br>
</blockquote></div>

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