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From: "Russell O'Connor" <roconnor@blockstream.io>
Date: Tue, 16 Aug 2016 18:36:24 -0400
Message-ID: <CAMZUoKktS=Ku4kpD0bocR4X__ZpWXrkPkdOyXBaYxjq+mr9Pmw@mail.gmail.com>
To: Pieter Wuille <pieter.wuille@gmail.com>
Content-Type: multipart/alternative; boundary=001a114950dcc3dc0b053a37fb37
Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] New BIP: Dealing with OP_IF and OP_NOTIF
 malleability in P2WSH
Precedence: list

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On Tue, Aug 16, 2016 at 6:30 PM, Pieter Wuille <pieter.wuille@gmail.com>
wrote:

> On Aug 17, 2016 00:23, "Russell O'Connor via bitcoin-dev" <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> > If one's goal is to mess with an transaction to prevent it from being
> mined, it is more effective to just not relay the transaction rather than
> to mess with the witness.  Given two transactions with the same txid and
> different witness data, miners and good nodes ought to mine/relay the
> version with the lower cost (smaller?) witness data.
>
> That implies that everyone will see both versions and be able to make that
> choice. Unfortunately, those two versions will be definition be in conflict
> with each other, and thus only one will end up paying a fee. We're can't
> relay two transactions for the price of one, or we'd expose the p2p network
> to a very cheap DDoS attack: just send increasingly small versions of the
> same transaction.
>
Can I already do something similar with replace by fee, or are there limits
on that?

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<div dir=3D"ltr">On Tue, Aug 16, 2016 at 6:30 PM, Pieter Wuille <span dir=
=3D"ltr">&lt;<a href=3D"mailto:pieter.wuille@gmail.com" target=3D"_blank">p=
ieter.wuille@gmail.com</a>&gt;</span> wrote:<br><div class=3D"gmail_extra">=
<div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margi=
n:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=3D"">=
<p dir=3D"ltr">On Aug 17, 2016 00:23, &quot;Russell O&#39;Connor via bitcoi=
n-dev&quot; &lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" ta=
rget=3D"_blank">bitcoin-dev@lists.<wbr>linuxfoundation.org</a>&gt; wrote:</=
p>
<p dir=3D"ltr">&gt; If one&#39;s goal is to mess with an transaction to pre=
vent it from being mined, it is more effective to just not relay the transa=
ction rather than to mess with the witness.=C2=A0 Given two transactions wi=
th the same txid and different witness data, miners and good nodes ought to=
 mine/relay the version with the lower cost (smaller?) witness data.</p>
</span><p dir=3D"ltr">That implies that everyone will see both versions and=
 be able to make that choice. Unfortunately, those two versions will be def=
inition be in conflict with each other, and thus only one will end up payin=
g a fee. We&#39;re can&#39;t relay two transactions for the price of one, o=
r we&#39;d expose the p2p network to a very cheap DDoS attack: just send in=
creasingly small versions of the same transaction.</p>

</blockquote><div>Can I already do something similar with replace by fee, o=
r are there limits on that? <br></div></div><br></div></div>

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