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References: <20160128185124.GA5140@savin.petertodd.org>
	<CAPg+sBgH0SegmFemRPA1BdAjgM=u3SZK=FDkZkbpuobEUQ1YHw@mail.gmail.com>
Date: Mon, 1 Feb 2016 19:29:32 +0000
Message-ID: <CAE-z3OWoeBbX2yJOiBanToytf5AAOnERNBe-XFDL+Sfv-KZe2w@mail.gmail.com>
From: Tier Nolan <tier.nolan@gmail.com>
Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary=089e013a22687e8e8f052aba67e0
Subject: Re: [bitcoin-dev] Segwit Upgrade Procedures & Block Extension Data
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On Mon, Feb 1, 2016 at 4:55 PM, Pieter Wuille via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> * The coinbase scriptSig gets a second number push (similar to the
> current BIP34 height push), which pushes a number O. O is a byte
> offset inside the coinbase transaction (excluding its witness data)
> that points to a 32-byte hash H. This is more flexible and more
> compact than what we have now (a suggestion by jl2012).
>

So, the script sig is  "<height> <offset> ..... <H>"?

Why is this just not the offset in the extra nonce?

> A significant design consideration is that if arbitrary data can be
> > added, it is very likely that miners will make use of that ability for
> > non-Bitcoin purposes;
> I agree with the concern, but I don't really understand how this idea
> solves it.
>
>
It could be enforced that the data in the coinbase witness stack has a
fixed number of entries, which depends on the block version number.
Version 5 blocks would only have 1 entry.

This would mean a soft-fork could be used to add new entries in the stack.
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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><div class=3D"gmail_quo=
te">On Mon, Feb 1, 2016 at 4:55 PM, Pieter Wuille via bitcoin-dev <span dir=
=3D"ltr">&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" targe=
t=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a>&gt;</span> wrote:<br=
><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1=
px #ccc solid;padding-left:1ex">
* The coinbase scriptSig gets a second number push (similar to the<br>
current BIP34 height push), which pushes a number O. O is a byte<br>
offset inside the coinbase transaction (excluding its witness data)<br>
that points to a 32-byte hash H. This is more flexible and more<br>
compact than what we have now (a suggestion by jl2012).<br></blockquote><di=
v><br></div><div>So, the script sig is=C2=A0 &quot;&lt;height&gt; &lt;offse=
t&gt; ..... &lt;H&gt;&quot;?<br></div><div>=C2=A0<br></div><div>Why is this=
 just not the offset in the extra nonce?<br></div><div><br></div></div><div=
 class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0 =
0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=3D"">
&gt; A significant design consideration is that if arbitrary data can be<br=
>
&gt; added, it is very likely that miners will make use of that ability for=
<br>
&gt; non-Bitcoin purposes; <br>
</span>I agree with the concern, but I don&#39;t really understand how this=
 idea solves it.<br>
<span class=3D"HOEnZb"><font color=3D"#888888"><br></font></span></blockquo=
te><div><br></div><div>It could be enforced that the data in the coinbase w=
itness stack has a fixed number of entries, which depends on the block vers=
ion number.=C2=A0 Version 5 blocks would only have 1 entry.<br><br></div><d=
iv>This would mean a soft-fork could be used to add new entries in the stac=
k. <br></div></div></div></div><div id=3D"DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9F=
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