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Date: Thu, 10 Apr 2014 21:12:00 +0100
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From: Tier Nolan <tier.nolan@gmail.com>
To: Pieter Wuille <pieter.wuille@gmail.com>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>,
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Subject: Re: [Bitcoin-development] Chain pruning
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--089e0158b03080362204f6b5d4b0
Content-Type: text/plain; charset=ISO-8859-1
On Thu, Apr 10, 2014 at 7:32 PM, Pieter Wuille <pieter.wuille@gmail.com>wrote:
> If you trust hashrate for determining which UTXO set is valid, a 51%
> attack becomes worse in that you can be made to believe a version of
> history which is in fact invalid.
>
If there are invalidation proofs, then this isn't strictly true.
If you are connected to 10 nodes and only 1 is honest, it can send you the
proof that your main chain is invalid.
For bad scripts, it shows you the input transaction for the invalid input
along with the merkle path to prove it is in a previous block.
For double spends, it could show the transaction which spent the output.
Double spends are pretty much the same as trying to spend non-existent
outputs anyway.
If the UTXO set commit was actually a merkle tree, then all updates could
be included.
Blocks could have extra data with the proofs that the UTXO set is being
updated correctly.
To update the UTXO set, you need the paths for all spent inputs.
It puts a large load on miners to keep things working, since they have to
run a full node.
If they commit the data to the chain, then SPV nodes can do local checking.
One of them will find invalid blocks eventually (even if one of the other
miners don't).
>
> --
> Pieter
>
>
> ------------------------------------------------------------------------------
> Put Bad Developers to Shame
> Dominate Development with Jenkins Continuous Integration
> Continuously Automate Build, Test & Deployment
> Start a new project now. Try Jenkins in the cloud.
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> Bitcoin-development@lists.sourceforge.net
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>
--089e0158b03080362204f6b5d4b0
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote">On T=
hu, Apr 10, 2014 at 7:32 PM, Pieter Wuille <span dir=3D"ltr"><<a href=3D=
"mailto:pieter.wuille@gmail.com" target=3D"_blank">pieter.wuille@gmail.com<=
/a>></span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
If you trust hashrate for determining which UTXO set is valid, a 51%<br>
attack becomes worse in that you can be made to believe a version of<br>
history which is in fact invalid.<br></blockquote><div><br></div><div>If th=
ere are invalidation proofs, then this isn't strictly true.<br><br></di=
v><div>If you are connected to 10 nodes and only 1 is honest, it can send y=
ou the proof that your main chain is invalid.<br>
<br></div><div>For bad scripts, it shows you the input transaction for the =
invalid input along with the merkle path to prove it is in a previous block=
.<br><br></div><div>For double spends, it could show the transaction which =
spent the output.<br>
<br></div><div>Double spends are pretty much the same as trying to spend no=
n-existent outputs anyway.<br><br></div><div>If the UTXO set commit was act=
ually a merkle tree, then all updates could be included.<br><br></div><div>
Blocks could have extra data with the proofs that the UTXO set is being upd=
ated correctly.<br></div><div><br></div><div>To update the UTXO set, you ne=
ed the paths for all spent inputs.<br><br></div><div>It puts a large load o=
n miners to keep things working, since they have to run a full node.=A0 <br=
>
<br></div><div>If they commit the data to the chain, then SPV nodes can do =
local checking.<br><br></div><div>One of them will find invalid blocks even=
tually (even if one of the other miners don't).<br></div><blockquote cl=
ass=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;p=
adding-left:1ex">
<div class=3D"HOEnZb"><div class=3D"h5"><br>
--<br>
Pieter<br>
<br>
---------------------------------------------------------------------------=
---<br>
Put Bad Developers to Shame<br>
Dominate Development with Jenkins Continuous Integration<br>
Continuously Automate Build, Test & Deployment<br>
Start a new project now. Try Jenkins in the cloud.<br>
<a href=3D"http://p.sf.net/sfu/13600_Cloudbees" target=3D"_blank">http://p.=
sf.net/sfu/13600_Cloudbees</a><br>
_______________________________________________<br>
Bitcoin-development mailing list<br>
<a href=3D"mailto:Bitcoin-development@lists.sourceforge.net">Bitcoin-develo=
pment@lists.sourceforge.net</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/bitcoin-development=
" target=3D"_blank">https://lists.sourceforge.net/lists/listinfo/bitcoin-de=
velopment</a><br>
</div></div></blockquote></div><br></div></div>
--089e0158b03080362204f6b5d4b0--
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