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References: <871s0c1tvg.fsf@rustcorp.com.au>
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From: "Russell O'Connor" <roconnor@blockstream.io>
Date: Mon, 3 Jun 2019 08:56:42 -0400
Message-ID: <CAMZUoKmXTONMqJ=0Vv7+e=q0CBL5h6Tio-5ec0bmZ+U4psOmCg@mail.gmail.com>
To: Rusty Russell <rusty@rustcorp.com.au>, 
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary="00000000000000730f058a6ae660"
Subject: Re: [bitcoin-dev] [PROPOSAL] Emergency RBF (BIP 125)
Precedence: list

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Hi Rusty,

On Sun, Jun 2, 2019 at 9:21 AM Rusty Russell via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> The new "emergency RBF" rule:
>
>  6. If the original transaction was not in the first 4,000,000 weight
>     units of the fee-ordered mempool and the replacement transaction is,
>     rules 3, 4 and 5 do not apply.
>
> This means:
>
> 3. This proposal does not open any significant new ability to RBF spam,
>    since it can (usually) only be used once.  IIUC bitcoind won't
>    accept more that 100 descendents of an unconfirmed tx anyway.
>

Is it not possible for Alice to grief Bob's node by alternating RBFing two
transactions, each one placing itself at the bottom of Bob's top 4,000,000
weight mempool which pushes the other one below the top 4,000,000 weight,
and then repeating with the other transaction?  It might be possible to
amend this proposal to partially mitigate this.

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<div dir=3D"ltr"><div>Hi Rusty,<br></div><br><div class=3D"gmail_quote"><di=
v dir=3D"ltr" class=3D"gmail_attr">On Sun, Jun 2, 2019 at 9:21 AM Rusty Rus=
sell via bitcoin-dev &lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundatio=
n.org">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:<br></div><block=
quote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1=
px solid rgb(204,204,204);padding-left:1ex">
The new &quot;emergency RBF&quot; rule:<br>
<br>
=C2=A06. If the original transaction was not in the first 4,000,000 weight<=
br>
=C2=A0 =C2=A0 units of the fee-ordered mempool and the replacement transact=
ion is,<br>
=C2=A0 =C2=A0 rules 3, 4 and 5 do not apply.<br>
<br>
This means:<br>
<br>3. This proposal does not open any significant new ability to RBF spam,=
<br>
=C2=A0 =C2=A0since it can (usually) only be used once.=C2=A0 IIUC bitcoind =
won&#39;t<br>
=C2=A0 =C2=A0accept more that 100 descendents of an unconfirmed tx anyway.<=
br></blockquote><div><br></div><div>Is it not possible for Alice to grief B=
ob&#39;s node by alternating RBFing two transactions, each one placing itse=
lf at the bottom of Bob&#39;s top 4,000,000 weight mempool which pushes the=
 other one below the top 4,000,000 weight, and then repeating with the othe=
r transaction?=C2=A0 It might be possible to amend this proposal to partial=
ly mitigate this.<br></div></div></div>

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