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From: Kalle Rosenbaum <kalle@rosenbaum.se>
Date: Mon, 28 Aug 2017 19:54:59 +0200
Message-ID: <CAPswA9wTeOtR5RF9YWfC-NTs__tf04RrXYFHVe-FTsJ3YChHQQ@mail.gmail.com>
To: Gregory Maxwell <greg@xiph.org>, 
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
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Subject: Re: [bitcoin-dev] Fwd: "Compressed" headers stream
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2017-08-28 19:12 GMT+02:00 Gregory Maxwell via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org>:

>
> The bits field can only change every 2016 blocks (4 bytes per header),
> the timestamp can not be less than the median of the last 11 and is
> usually only a small amount over the last one (saves 2 bytes per
> header), the block version is usually one of the last few (save 3
> bytes per header).
>

 ... and I guess the nonce can be arbitrarily truncated as well, just brute
force the missing bits :-P.


> But all these things improvements are just a constant factor. I think
> you want the compact SPV proofs described in the appendix of the
> sidechains whitepaper which creates log scaling proofs.
>

I think that my blog post on compact spv proofs can be helpful also. It
tries to make the pretty compact formulations in the sidechains paper a bit
more graspable by normal people.

http://popeller.io/index.php/2016/09/15/compact-spv-proofs/

Kalle

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<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote">2017=
-08-28 19:12 GMT+02:00 Gregory Maxwell via bitcoin-dev <span dir=3D"ltr">&l=
t;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank=
">bitcoin-dev@lists.linuxfoundation.org</a>&gt;</span>:<br><blockquote clas=
s=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid r=
gb(204,204,204);padding-left:1ex"><br>
The bits field can only change every 2016 blocks (4 bytes per header),<br>
the timestamp can not be less than the median of the last 11 and is<br>
usually only a small amount over the last one (saves 2 bytes per<br>
header), the block version is usually one of the last few (save 3<br>
bytes per header).<br></blockquote><div><br></div><div>=C2=A0... and I gues=
s the nonce can be arbitrarily truncated as well, just brute force the miss=
ing bits :-P.</div><div><br></div><blockquote class=3D"gmail_quote" style=
=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding=
-left:1ex">
<br>
But all these things improvements are just a constant factor. I think<br>
you want the compact SPV proofs described in the appendix of the<br>
sidechains whitepaper which creates log scaling proofs.<br></blockquote><di=
v><br></div><div>I think that my blog post on compact spv proofs can be hel=
pful also. It tries to make the pretty compact formulations in the sidechai=
ns paper a bit more graspable by normal people.=C2=A0</div><div><br></div><=
div><a href=3D"http://popeller.io/index.php/2016/09/15/compact-spv-proofs/"=
>http://popeller.io/index.php/2016/09/15/compact-spv-proofs/</a>=C2=A0</div=
><div><br></div><div>Kalle</div></div></div></div>

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