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From: Kevin Pan <bit.kevin@gmail.com>
Date: Sun, 8 Oct 2017 17:28:32 +0800
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Subject: Re: [bitcoin-dev] A solution may solve Block Withholding Attack
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But I think this one is simpler and better than Luke's.

And now is different like 2012, pools need be more independ today. Pools
want
to express their opinion or standpoint. Some of can't do that like remove
the
NYA tag and one the reason is the Block Withholding Attack.

Kevin Pan

On Fri, Oct 6, 2017 at 10:36 PM, James Hilliard <james.hilliard1@gmail.com>
wrote:

> There have been some other proposals to deal with this such as
> https://lists.linuxfoundation.org/pipermail/bitcoin-dev/
> 2012-June/001506.html
> that may be possible to implement in existing miners.
>
> On Tue, Oct 3, 2017 at 9:52 AM, =E6=BD=98=E5=BF=97=E5=BD=AA via bitcoin-d=
ev
> <bitcoin-dev@lists.linuxfoundation.org> wrote:
> > Here is a solution may solve Block Withholding Attack. The general idea
> is
> > came from Aviv Zohar(avivz@cs.huji.ac.il), I made it work for Bitcoin.
> > Anyway, thanks Aviv.
> >
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> >
> > DIFF_1 =3D 0x00000000FFFF0000000000000000000000000000000000000000000000
> 000000;
> >
> > Diff =3D DIFF_1 / target
> >
> > this is equal to
> >
> > Diff =3D DIFF_1 / (target - 0) or Diff =3D DIFF_1 / abs(target - 0)
> >
> > now, we change diff algo to below:
> >
> > New_Diff =3D DIFF_1 / abs(target - offset)
> >
> > Offset is 32 bytes, like uint256 in Bitcoin, range is [0, 2^256),
> > define: offset_hash =3D DSHA256(offset).
> >
> > we need to do a little change to the merkle root hash algo, put the
> > offset_hash as a tx hash in the front of tx hashes.
> >
> > [offset_hash, coinbase_tx_hash, tx01_hash, tx02_hash, =E2=80=A6 , tx_n_=
hash]
> >
> > Actually could put offset_hash in any place in the array of hashes.
> >
> > network_hash_range =3D network_hash_end - network_hash_begin
> >
> > miner_hash_range =3D miner_hash_end - miner_hash_begin
> >
> > The offset value MUST between network_hash_begin/end or
> > miner_hash_begin/end.
> >
> > https://user-images.githubusercontent.com/514951/
> 31133378-e00d9ca2-a891-11e7-8c61-73325f59f6ed.JPG
> >
> > When mining pool send a job to miners, put the PoW hash range
> > (miner_hash_begin/end) in the job. So if the miners find a hash which
> value
> > is between [miner_hash_begin, miner_hash_end], means it's SHOULD be a
> > valid share, could submit the share to the pool. If the hash value is
> > between [network_hash_begin, network_hash_end] means find a valid block=
.
> >
> > The network_diff is much much high than the miner's diff, means the
> > network_hash_range is much much smaller than miner_hash_range. By now,
> > a typical miner's pool diff is around 16K, network diff is 112386328513=
2,
> > so miner_hash_range is at least million times bigger than
> > network_hash_range.
> > The miners only know miner_hash_range, it's impossible for cheat miners
> > to find out which share could make a valid block or not.
> >
> > Problems:
> > 1. it's a hard fork.
> > 2. will make existed asic dsha256 chips useless, but I think it's only =
a
> > small change to make new asic chips based on existed tech.
> >
> > _______________________________________________
> > 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"><span style=3D"font-size:12.8px">But I think this one is s=
impler and better than Luke&#39;s.</span><div style=3D"font-size:12.8px"><b=
r></div><div style=3D"font-size:12.8px">And now is different like 2012, poo=
ls need be more independ today. Pools want=C2=A0</div><div style=3D"font-si=
ze:12.8px">to express their opinion or standpoint. Some of can&#39;t do tha=
t like remove the=C2=A0</div><div style=3D"font-size:12.8px">NYA tag and on=
e the reason is the Block Withholding Attack.</div><div style=3D"font-size:=
12.8px"><br></div><div style=3D"font-size:12.8px">Kevin Pan</div></div><div=
 class=3D"gmail_extra"><br><div class=3D"gmail_quote">On Fri, Oct 6, 2017 a=
t 10:36 PM, James Hilliard <span dir=3D"ltr">&lt;<a href=3D"mailto:james.hi=
lliard1@gmail.com" target=3D"_blank">james.hilliard1@gmail.com</a>&gt;</spa=
n> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;b=
order-left:1px #ccc solid;padding-left:1ex">There have been some other prop=
osals to deal with this such as<br>
<a href=3D"https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2012-Jun=
e/001506.html" rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoun=
dation.<wbr>org/pipermail/bitcoin-dev/<wbr>2012-June/001506.html</a><br>
that may be possible to implement in existing miners.<br>
<div><div class=3D"h5"><br>
On Tue, Oct 3, 2017 at 9:52 AM, =E6=BD=98=E5=BF=97=E5=BD=AA via bitcoin-dev=
<br>
&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@li=
sts.<wbr>linuxfoundation.org</a>&gt; wrote:<br>
&gt; Here is a solution may solve Block Withholding Attack. The general ide=
a is<br>
&gt; came from Aviv Zohar(<a href=3D"mailto:avivz@cs.huji.ac.il">avivz@cs.h=
uji.ac.il</a>), I made it work for Bitcoin.<br>
&gt; Anyway, thanks Aviv.<br>
&gt;<br>
&gt; =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D<br>
&gt;<br>
&gt; DIFF_1 =3D 0x00000000FFFF0000000000000000<wbr>000000000000000000000000=
000000<wbr>000000;<br>
&gt;<br>
&gt; Diff =3D DIFF_1 / target<br>
&gt;<br>
&gt; this is equal to<br>
&gt;<br>
&gt; Diff =3D DIFF_1 / (target - 0) or Diff =3D DIFF_1 / abs(target - 0)<br=
>
&gt;<br>
&gt; now, we change diff algo to below:<br>
&gt;<br>
&gt; New_Diff =3D DIFF_1 / abs(target - offset)<br>
&gt;<br>
&gt; Offset is 32 bytes, like uint256 in Bitcoin, range is [0, 2^256),<br>
&gt; define: offset_hash =3D DSHA256(offset).<br>
&gt;<br>
&gt; we need to do a little change to the merkle root hash algo, put the<br=
>
&gt; offset_hash as a tx hash in the front of tx hashes.<br>
&gt;<br>
&gt; [offset_hash, coinbase_tx_hash, tx01_hash, tx02_hash, =E2=80=A6 , tx_n=
_hash]<br>
&gt;<br>
&gt; Actually could put offset_hash in any place in the array of hashes.<br=
>
&gt;<br>
&gt; network_hash_range =3D network_hash_end - network_hash_begin<br>
&gt;<br>
&gt; miner_hash_range =3D miner_hash_end - miner_hash_begin<br>
&gt;<br>
&gt; The offset value MUST between network_hash_begin/end or<br>
&gt; miner_hash_begin/end.<br>
&gt;<br>
&gt; <a href=3D"https://user-images.githubusercontent.com/514951/31133378-e=
00d9ca2-a891-11e7-8c61-73325f59f6ed.JPG" rel=3D"noreferrer" target=3D"_blan=
k">https://user-images.<wbr>githubusercontent.com/514951/<wbr>31133378-e00d=
9ca2-a891-11e7-<wbr>8c61-73325f59f6ed.JPG</a><br>
&gt;<br>
&gt; When mining pool send a job to miners, put the PoW hash range<br>
&gt; (miner_hash_begin/end) in the job. So if the miners find a hash which =
value<br>
&gt; is between [miner_hash_begin, miner_hash_end], means it&#39;s SHOULD b=
e a<br>
&gt; valid share, could submit the share to the pool. If the hash value is<=
br>
&gt; between [network_hash_begin, network_hash_end] means find a valid bloc=
k.<br>
&gt;<br>
&gt; The network_diff is much much high than the miner&#39;s diff, means th=
e<br>
&gt; network_hash_range is much much smaller than miner_hash_range. By now,=
<br>
&gt; a typical miner&#39;s pool diff is around 16K, network diff is 1123863=
285132,<br>
&gt; so miner_hash_range is at least million times bigger than<br>
&gt; network_hash_range.<br>
&gt; The miners only know miner_hash_range, it&#39;s impossible for cheat m=
iners<br>
&gt; to find out which share could make a valid block or not.<br>
&gt;<br>
&gt; Problems:<br>
&gt; 1. it&#39;s a hard fork.<br>
&gt; 2. will make existed asic dsha256 chips useless, but I think it&#39;s =
only a<br>
&gt; small change to make new asic chips based on existed tech.<br>
&gt;<br>
</div></div>&gt; ______________________________<wbr>_________________<br>
&gt; bitcoin-dev mailing list<br>
&gt; <a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@l=
ists.<wbr>linuxfoundation.org</a><br>
&gt; <a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-=
dev" rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.<wb=
r>org/mailman/listinfo/bitcoin-<wbr>dev</a><br>
&gt;<br>
</blockquote></div><br></div>

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