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From: Johnson Lau <jl2012@xbt.hk>
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Date: Mon, 3 Apr 2017 11:36:13 +0800
In-Reply-To: <CAMZUoKkFh-uBwzTZoJ0kzyJukEG2HeDf_VmTwgZMm1esD+TaFQ@mail.gmail.com>
To: Russell O'Connor <roconnor@blockstream.io>
References: <2D094CEC-3756-45B0-970F-1EB33DF352C5@xbt.hk>
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Subject: Re: [bitcoin-dev] BIP draft: Extended block header hardfork
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> On 3 Apr 2017, at 04:39, Russell O'Connor <roconnor@blockstream.io> =
wrote:
>=20
> On Sun, Apr 2, 2017 at 4:13 PM, Johnson Lau via bitcoin-dev =
<bitcoin-dev@lists.linuxfoundation.org =
<mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote:
> =E2=80=A2 the witness of the first input of the coinbase =
transaction MUST have exactly one stack item (the "extended header"), =
with the following data:
> =E2=80=A2 bytes 0 to 3: nHeight MUST be equal to the =
height of this block (signed little endian)
>=20
> Someone told me a while back that it would be more natural if we move =
the nHeight from the coinbase script to the coinbase locktime. Have you =
considered doing this?
Yes, it=E2=80=99d look much better. But I=E2=80=99m thinking of a =
different approach: instead of using a hash of 0000=E2=80=A6.0000, we =
use the hash of previous block for the coinbase input. With some new =
SIGHASH design, this allows people to pay to a child of a particular =
block. This is actually implemented in my spoonnet2 branch. I=E2=80=99ll =
describe it with a BIP soon
However, what I=E2=80=99m trying to do in the extended block header is =
independent to the design of coinbase tx. Here I=E2=80=99m trying to let =
people knowing the height just by a header and extended header (<300 =
bytes), without requiring all headers in the history.
Also I forgot to post the link of the BIP: =
https://github.com/jl2012/bips/blob/spoonnet/bip-extheader.mediawiki =
<https://github.com/jl2012/bips/blob/spoonnet/bip-extheader.mediawiki>=
--Apple-Mail=_1C116E78-B8FE-4131-986A-7A3B0B626FC1
Content-Transfer-Encoding: quoted-printable
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charset=utf-8
<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" =
class=3D""><br class=3D""><div><blockquote type=3D"cite" class=3D""><div =
class=3D"">On 3 Apr 2017, at 04:39, Russell O'Connor <<a =
href=3D"mailto:roconnor@blockstream.io" =
class=3D"">roconnor@blockstream.io</a>> wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><div dir=3D"ltr" =
class=3D"">On Sun, Apr 2, 2017 at 4:13 PM, Johnson Lau via bitcoin-dev =
<span dir=3D"ltr" class=3D""><<a =
href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank" =
class=3D"">bitcoin-dev@lists.linuxfoundation.org</a>></span> =
wrote:<br class=3D""><div class=3D"gmail_extra"><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"> =
=E2=80=A2 the witness of the first input of the coinbase =
transaction MUST have exactly one stack item (the "extended header"), =
with the following data:<br class=3D"">
=E2=80=A2 bytes =
0 to 3: nHeight MUST be equal to the height of this block (signed little =
endian)<br class=3D""></blockquote><div class=3D""><br =
class=3D""></div><div class=3D""> Someone told me a while back that =
it would be more natural if we move the nHeight from the coinbase script =
to the coinbase locktime. Have you considered doing this?<br =
class=3D""></div></div></div></div>
</div></blockquote></div><div class=3D""><br class=3D""></div><div =
class=3D"">Yes, it=E2=80=99d look much better. But I=E2=80=99m thinking =
of a different approach: instead of using a hash of 0000=E2=80=A6.0000, =
we use the hash of previous block for the coinbase input. With some new =
SIGHASH design, this allows people to pay to a child of a particular =
block. This is actually implemented in my spoonnet2 branch. I=E2=80=99ll =
describe it with a BIP soon</div><div class=3D""><br class=3D""></div><div=
class=3D"">However, what I=E2=80=99m trying to do in the extended block =
header is independent to the design of coinbase tx. Here I=E2=80=99m =
trying to let people knowing the height just by a header and extended =
header (<300 bytes), without requiring all headers in the =
history.</div><div class=3D""><br class=3D""></div><div class=3D"">Also =
I forgot to post the link of the BIP: <a =
href=3D"https://github.com/jl2012/bips/blob/spoonnet/bip-extheader.mediawi=
ki" =
class=3D"">https://github.com/jl2012/bips/blob/spoonnet/bip-extheader.medi=
awiki</a></div></body></html>=
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