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In-Reply-To: <CAK=nyAxOa8fsVfxucH7WTTMn25BCzgQ28h_sNsunedpCoRXjjQ@mail.gmail.com>
From: "Russell O'Connor" <roconnor@blockstream.com>
Date: Fri, 16 Apr 2021 09:56:11 -0400
Message-ID: <CAMZUoKmR6ZU6mAgEhKDD5cTMuja_OC0_Sz3x4UND=E-g1PkgsQ@mail.gmail.com>
To: Christopher Gilliard <christopher.gilliard@gmail.com>, 
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary="000000000000548f5805c017584a"
Subject: Re: [bitcoin-dev] BIP - limiting OP_RETURN / HF
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Firstly, a minor point is that your proposal is a soft-fork, not a
hard-fork.

But more importantly, adding limitations on OP_RETURN transactions is not
helpful.  Users who want to embed arbitrary data in their transactions can
always do so by encoding their data inside the values of legacy
multi-signature scriptpubkeys (pubkeys can be generated without knowing the
private key in order to encode non-key related data).  Not only can users
do this, users have done this in the past.  However, this behaviour is
problematic because such multi-signature "data" scriptpubkeys are
indistinguishable from "real" multisignature scriptpubkeys, and thus must
be kept in the UTXO set.  This differs from outputs using OP_RETURN which
are provably unspendable, and therefore can be safely omitted from the UTXO
set.

Thus, given that it is otherwise impossible to stop people from putting
arbitrary data values into their transactions, then we rather encourage
people who are going to encode their arbitrary data in transaction to use
the OP_RETURN outputs in order to avoid UTXO bloat.

Also, as it stands, fees already nudge various participants to consolidate
their data in the way that you suggest they do.

On Fri, Apr 16, 2021 at 9:32 AM Christopher Gilliard via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> I have created a BIP which can be found here:
> https://github.com/cgilliard/bips/blob/notarization/bip-XXXX.mediawiki
>
> I'm sending this email to start the discussion regarding this proposal. If
> there are any comments/suggestions, please let me know.
>
> Regards,
> Chris
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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<div dir=3D"ltr"><div>Firstly, a minor point is that your proposal is a sof=
t-fork, not a hard-fork.</div><div><br></div><div>But more importantly, add=
ing limitations on OP_RETURN transactions is not helpful.=C2=A0 Users who w=
ant to embed arbitrary data in their transactions can always do so by encod=
ing their data inside the values of legacy multi-signature scriptpubkeys (p=
ubkeys can be generated without knowing the private key in order to encode =
non-key related data).=C2=A0 Not only can users do this, users have done th=
is in the past.=C2=A0 However, this behaviour is problematic because such m=
ulti-signature &quot;data&quot; scriptpubkeys are indistinguishable from &q=
uot;real&quot; multisignature scriptpubkeys, and thus must be kept in the U=
TXO set.=C2=A0 This differs from outputs using OP_RETURN which are provably=
 unspendable, and therefore can be safely omitted from the UTXO set.</div><=
div><br></div><div>Thus, given that it is otherwise impossible to stop peop=
le from putting arbitrary data values into their transactions, then we rath=
er encourage people who are going to encode their arbitrary data in transac=
tion to use the OP_RETURN outputs in order to avoid UTXO bloat. </div><div>=
<br></div><div>Also, as it stands, fees already nudge various participants =
to consolidate their data in the way that you suggest they do.<br></div><br=
><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Fri, A=
pr 16, 2021 at 9:32 AM Christopher Gilliard via bitcoin-dev &lt;<a href=3D"=
mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linuxfounda=
tion.org</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D=
"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-le=
ft:1ex"><div dir=3D"ltr">I have created a BIP which can be found here:=C2=
=A0<a href=3D"https://github.com/cgilliard/bips/blob/notarization/bip-XXXX.=
mediawiki" target=3D"_blank">https://github.com/cgilliard/bips/blob/notariz=
ation/bip-XXXX.mediawiki</a><div><br></div><div>I&#39;m sending this email =
to start the discussion regarding this proposal. If there are any comments/=
suggestions, please let me know.</div><div><br></div><div>Regards,</div><di=
v>Chris</div></div>
_______________________________________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">=
bitcoin-dev@lists.linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.org/mail=
man/listinfo/bitcoin-dev</a><br>
</blockquote></div></div>

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