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From: Jannes Faber <jannes.faber@gmail.com>
Date: Wed, 11 May 2016 12:47:58 +0200
Message-ID: <CABeL=0ih+BB+AKO6uJRCDGZoVo5is4+GBUfQAJkE48Pd_4vzOQ@mail.gmail.com>
To: Henning Kopp <henning.kopp@uni-ulm.de>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Making AsicBoost irrelevant
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On 11 May 2016 at 12:36, Henning Kopp <henning.kopp@uni-ulm.de> wrote:

> On Wed, May 11, 2016 at 11:21:10AM +0200, Jannes Faber via bitcoin-dev
> wrote:
> > On 11 May 2016 at 05:14, Timo Hanke via bitcoin-dev <
> > bitcoin-dev@lists.linuxfoundation.org> wrote:
> >
> > > There is no way to tell from a block if it was mined with AsicBoost o=
r
> > > not. So you don=E2=80=99t know what percentage of the hashrate uses A=
sicBoost
> at
> > > any point in time. How can you risk forking that percentage out? Note
> that
> > > this would be a GUARANTEED chain fork. Meaning that after you change
> the
> > > block mining algorithm some percentage of hardware will no longer be
> able
> > > to produce valid blocks. That hardware cannot =E2=80=9Cswitch over=E2=
=80=9D to the
> majority
> > > chain even if it wanted to. Hence you are guaranteed to have two
> > > co-existing bitcoin blockchains afterwards.
> > >
> > > Again: this is unlike the hypothetical persistence of two chains afte=
r
> a
> > > hardfork that is only contentious but doesn=E2=80=99t change the mini=
ng
> algorithm,
> > > the kind of hardfork you are proposing would guarantee the persistenc=
e
> of
> > > two chains.
> > >
> >
> > Assuming AsicBoost miners are in the minority, their chain will
> constantly
> > get overtaken. So it will not be one endless hard fork as you claim, bu=
t
> > rather AsicBoost blocks will continue to be ignored (orphaned) until th=
ey
> > stop making them.
>
> At least until a difficulty adjustment on the AsicBoost chain takes
> place. From that point on, both chains, the AsicBoost one and the
> forked one will grow approximately at the same speed.
>
>
No: you are still assuming AsicBoost miners would reject normal blocks.
They don't now and they would have to specifically code for that as a reply
to AsicBoost being banned. So there won't be two chains at all, only the
main chain with a lot (more than usual) of short (few blocks) forks. Each
forks starts anew, it's not one long fork. Therefore there is no
"difficulty adjustment on the AiscBoost chain".

Now if they do decide to ban non-AsicBoost blocks as a response to being
banned themselves, they're just another altcoin with a different PoW and no
one would have a reason to use them over Bitcoin (apart from maybe selling
those forked coins asap).

You're confused about what "longest" means as well: it's not just the
number of blocks, it's the aggregate difficulty that counts: so AsicBoost
would never become "longer" (more total work) either.

Hope this helps clear things up.

--
Jannes

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<div dir=3D"ltr">On 11 May 2016 at 12:36, Henning Kopp <span dir=3D"ltr">&l=
t;<a href=3D"mailto:henning.kopp@uni-ulm.de" target=3D"_blank">henning.kopp=
@uni-ulm.de</a>&gt;</span> wrote:<br><div class=3D"gmail_extra"><div class=
=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8=
ex;border-left:1px #ccc solid;padding-left:1ex"><span class=3D"">On Wed, Ma=
y 11, 2016 at 11:21:10AM +0200, Jannes Faber via bitcoin-dev wrote:<br>
&gt; On 11 May 2016 at 05:14, Timo Hanke via bitcoin-dev &lt;<br>
&gt; <a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@l=
ists.linuxfoundation.org</a>&gt; wrote:<br>
&gt;<br>
&gt; &gt; There is no way to tell from a block if it was mined with AsicBoo=
st or<br>
&gt; &gt; not. So you don=E2=80=99t know what percentage of the hashrate us=
es AsicBoost at<br>
&gt; &gt; any point in time. How can you risk forking that percentage out? =
Note that<br>
&gt; &gt; this would be a GUARANTEED chain fork. Meaning that after you cha=
nge the<br>
&gt; &gt; block mining algorithm some percentage of hardware will no longer=
 be able<br>
&gt; &gt; to produce valid blocks. That hardware cannot =E2=80=9Cswitch ove=
r=E2=80=9D to the majority<br>
&gt; &gt; chain even if it wanted to. Hence you are guaranteed to have two<=
br>
&gt; &gt; co-existing bitcoin blockchains afterwards.<br>
&gt; &gt;<br>
&gt; &gt; Again: this is unlike the hypothetical persistence of two chains =
after a<br>
&gt; &gt; hardfork that is only contentious but doesn=E2=80=99t change the =
mining algorithm,<br>
&gt; &gt; the kind of hardfork you are proposing would guarantee the persis=
tence of<br>
&gt; &gt; two chains.<br>
&gt; &gt;<br>
&gt;<br>
&gt; Assuming AsicBoost miners are in the minority, their chain will consta=
ntly<br>
&gt; get overtaken. So it will not be one endless hard fork as you claim, b=
ut<br>
&gt; rather AsicBoost blocks will continue to be ignored (orphaned) until t=
hey<br>
&gt; stop making them.<br>
<br>
</span>At least until a difficulty adjustment on the AsicBoost chain takes<=
br>
place. From that point on, both chains, the AsicBoost one and the<br>
forked one will grow approximately at the same speed.<br>
<br></blockquote><div><br></div><div>No: you are still assuming AsicBoost m=
iners would reject normal blocks. They don&#39;t now and they would have to=
 specifically code for that as a reply to AsicBoost being banned. So there =
won&#39;t be two chains at all, only the main chain with a lot (more than u=
sual) of short (few blocks) forks. Each forks starts anew, it&#39;s not one=
 long fork. Therefore there is no &quot;difficulty adjustment on the AiscBo=
ost chain&quot;.<br><br></div><div>Now if they do decide to ban non-AsicBoo=
st blocks as a response to being banned themselves, they&#39;re just anothe=
r altcoin with a different PoW and no one would have a reason to use them o=
ver Bitcoin (apart from maybe selling those forked coins asap).<br><br></di=
v><div>You&#39;re confused about what &quot;longest&quot; means as well: it=
&#39;s not just the number of blocks, it&#39;s the aggregate difficulty tha=
t counts: so AsicBoost would never become &quot;longer&quot; (more total wo=
rk) either.<br></div><br></div><div class=3D"gmail_quote">Hope this helps c=
lear things up.<br></div><div class=3D"gmail_quote"><br>--<br></div><div cl=
ass=3D"gmail_quote">Jannes<br></div></div></div>

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