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Date: Mon, 10 Apr 2017 11:16:50 +0200
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On 9 Apr 2017 4:01 pm, "Jimmy Song" <jaejoon@gmail.com> wrote:

Jorge,

Why won't the attacker use asicboost too? (Please don't say because of
> patents)
>
>
We're assuming the ASIC optimization in my example is incompatible with
ASICBoost. But if the new optimization were compatible with ASICBoost,
you're right, the network would be in an equivalent situation whether
ASICBoost was banned or not.


Only if all honest miners use asicboost, otherwise the situation for an
attack is not equivalent but worse with asicboost.

I want to point out again that overt ASICBoost can be used on the network
today. My proposal is to bring ASICBoost usage out into the open vs hiding
it. Banning ASICBoost via protocol changes is another issue completely.


Doesn't greg's proposal of disabling covert asicboost "bring asicboost
usage into the open vs hiding it" too? It also does it without making any
assumptions on whether we want to completely disable it later (I want)
while your proposal assumes we do not.

Jimmy


> On 9 Apr 2017 12:26 am, "Jimmy Song" <jaejoon@gmail.com> wrote:
>
>> Jorge,
>>
>> Suppose someone figures out an ASIC optimization that's completely
>> unrelated that gives X% speed boost over your non-ASICBoosted
>> implementation. If you ban ASICBoost, someone with this optimization can
>> get 51% of the network by adding N machines with their new optimization.=
 If
>> you allow ASICBoost and assuming this gets a 20% speed boost over
>> non-ASICBoosted hardware, someone with this optimization would need 1.2N
>> machines to get 51%. The network in that sense is 20% stronger against t=
his
>> attack in terms of cost.
>>
>> Jimmy
>>
>> On Sat, Apr 8, 2017 at 12:22 PM, Jorge Tim=C3=B3n <jtimon@jtimon.cc> wro=
te:
>>
>>> To be more specific, why "being higher will secure the Bitcoin network
>>> better against newer optimizations"?
>>> Or, to be more clear, let's forget about future "optimizations", let's
>>> just think of an attacker. Does asicboost being used by all miners
>>> make the system more secure against an attacker? No, for the attacker
>>> can use asicboost too.
>>> What about the case when not all the miners are using asicboost? Then
>>> the attacker can actually get an advantage by suing asicboost.
>>>
>>> Sometimes people compare asicboost with the use of asics in general as
>>> both providing more security for the network and users. But I don't
>>> think this is accurate. The existence of sha256d asics makes an attack
>>> with general purpose computing hardware (or even more specialized
>>> architectures like gpgpu) much more expensive and unlikely. As an
>>> alternative the attacker can spend additional resources investing in
>>> asics himself (again, making many attacks more expensive and
>>> unlikely).
>>>
>>> But as far as I know, asicboost can be implemented with software
>>> running on general purpose hardware that integrates with regular
>>> sha256d asics. There is probably an advantage on having the asicboost
>>> implementation "in the same box" as the sha256d, yet again the
>>> attacker can invest in hardware with the competitive advantage from
>>> having asicboost more intergrated with the sha256d asics too.
>>>
>>> To reiterate, whether all miners use asicboost or only a subset of
>>> them, I remain unconvinced that provides any additional security to
>>> the network (to be more precise whether that makes "tx history harder
>>> to rewrite"), even if it results on the hashrate charts looking "more
>>> secure".
>>>
>>>
>>> On Sat, Apr 8, 2017 at 6:27 PM, Jorge Tim=C3=B3n <jtimon@jtimon.cc> wro=
te:
>>> >
>>> >
>>> > On 8 Apr 2017 5:06 am, "Jimmy Song via bitcoin-dev"
>>> > <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>> >
>>> > Praxeology Guy,
>>> >
>>> >> Why would the actual end users of Bitcoin (the long term and short
>>> term
>>> >> owners of bitcoins) who run fully verifying nodes want to change
>>> Bitcoin
>>> >> policy in order to make their money more vulnerable to 51% attack?
>>> >
>>> >
>>> > Certainly, if only one company made use of the extra nonce space, the=
y
>>> would
>>> > have an advantage. But think of it this way, if some newer ASIC
>>> optimization
>>> > comes up, would you rather have a non-ASICBoosted hash rate to defend
>>> with
>>> > or an ASICBoosted hash rate? Certainly, the latter, being higher will
>>> secure
>>> > the Bitcoin network better against newer optimizations.
>>> >
>>> >
>>> > Why?
>>>
>>
>>

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<div dir=3D"auto"><div><br><div class=3D"gmail_extra"><br><div class=3D"gma=
il_quote">On 9 Apr 2017 4:01 pm, &quot;Jimmy Song&quot; &lt;<a href=3D"mail=
to:jaejoon@gmail.com">jaejoon@gmail.com</a>&gt; wrote:<br type=3D"attributi=
on"><blockquote class=3D"quote" style=3D"margin:0 0 0 .8ex;border-left:1px =
#ccc solid;padding-left:1ex"><div dir=3D"ltr">Jorge,<br><div class=3D"gmail=
_extra"><br><div class=3D"gmail_quote"><div class=3D"quoted-text"><blockquo=
te class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc so=
lid;padding-left:1ex"><div dir=3D"auto">Why won&#39;t the attacker use asic=
boost too? (Please don&#39;t say because of patents)</div><div class=3D"m_8=
028033458476356323HOEnZb"><div class=3D"m_8028033458476356323h5"><div class=
=3D"gmail_extra"><br></div></div></div></blockquote><div><br></div></div><d=
iv>We&#39;re assuming the ASIC optimization in my example is incompatible w=
ith ASICBoost. But if the new optimization were compatible with ASICBoost, =
you&#39;re right, the network would be in an equivalent situation whether A=
SICBoost was banned or not.</div></div></div></div></blockquote></div></div=
></div><div dir=3D"auto"><br></div><div dir=3D"auto">Only if all honest min=
ers use asicboost, otherwise the situation for an attack is not equivalent =
but worse with asicboost.</div><div dir=3D"auto"><br></div><div dir=3D"auto=
"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><blockquote class=
=3D"quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-le=
ft:1ex"><div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quo=
te"><div>I want to point out again that overt ASICBoost can be used on the =
network today. My proposal is to bring ASICBoost usage out into the open vs=
 hiding it. Banning ASICBoost via protocol changes is another issue complet=
ely.</div></div></div></div></blockquote></div></div></div><div dir=3D"auto=
"><br></div><div dir=3D"auto">Doesn&#39;t greg&#39;s proposal of disabling =
covert asicboost &quot;bring asicboost usage into the open vs hiding it&quo=
t; too? It also does it without making any assumptions on whether we want t=
o completely disable it later (I want) while your proposal assumes we do no=
t.</div><div dir=3D"auto"><br></div><div dir=3D"auto"><div class=3D"gmail_e=
xtra"><div class=3D"gmail_quote"><blockquote class=3D"quote" style=3D"margi=
n:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr">=
<div class=3D"gmail_extra"><div class=3D"gmail_quote"><font color=3D"#88888=
8"><div>Jimmy</div></font><div class=3D"elided-text"><div>=C2=A0</div><bloc=
kquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #cc=
c solid;padding-left:1ex"><div class=3D"m_8028033458476356323HOEnZb"><div c=
lass=3D"m_8028033458476356323h5"><div class=3D"gmail_extra"><div class=3D"g=
mail_quote">On 9 Apr 2017 12:26 am, &quot;Jimmy Song&quot; &lt;<a href=3D"m=
ailto:jaejoon@gmail.com" target=3D"_blank">jaejoon@gmail.com</a>&gt; wrote:=
<br type=3D"attribution"><blockquote class=3D"gmail_quote" style=3D"margin:=
0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr">Jo=
rge,<div><br></div><div>Suppose someone figures out an ASIC optimization th=
at&#39;s completely unrelated that gives X% speed boost over your non-ASICB=
oosted implementation. If you ban ASICBoost, someone with this optimization=
 can get 51% of the network by adding N machines with their new optimizatio=
n. If you allow ASICBoost and assuming this gets a 20% speed boost over non=
-ASICBoosted hardware, someone with this optimization would need 1.2N machi=
nes to get 51%. The network in that sense is 20% stronger against this atta=
ck in terms of cost.</div><div><br></div><div>Jimmy</div></div><div class=
=3D"gmail_extra"><br><div class=3D"gmail_quote">On Sat, Apr 8, 2017 at 12:2=
2 PM, Jorge Tim=C3=B3n <span dir=3D"ltr">&lt;<a href=3D"mailto:jtimon@jtimo=
n.cc" target=3D"_blank">jtimon@jtimon.cc</a>&gt;</span> wrote:<br><blockquo=
te class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc so=
lid;padding-left:1ex">To be more specific, why &quot;being higher will secu=
re the Bitcoin network<br>
better against newer optimizations&quot;?<br>
Or, to be more clear, let&#39;s forget about future &quot;optimizations&quo=
t;, let&#39;s<br>
just think of an attacker. Does asicboost being used by all miners<br>
make the system more secure against an attacker? No, for the attacker<br>
can use asicboost too.<br>
What about the case when not all the miners are using asicboost? Then<br>
the attacker can actually get an advantage by suing asicboost.<br>
<br>
Sometimes people compare asicboost with the use of asics in general as<br>
both providing more security for the network and users. But I don&#39;t<br>
think this is accurate. The existence of sha256d asics makes an attack<br>
with general purpose computing hardware (or even more specialized<br>
architectures like gpgpu) much more expensive and unlikely. As an<br>
alternative the attacker can spend additional resources investing in<br>
asics himself (again, making many attacks more expensive and<br>
unlikely).<br>
<br>
But as far as I know, asicboost can be implemented with software<br>
running on general purpose hardware that integrates with regular<br>
sha256d asics. There is probably an advantage on having the asicboost<br>
implementation &quot;in the same box&quot; as the sha256d, yet again the<br=
>
attacker can invest in hardware with the competitive advantage from<br>
having asicboost more intergrated with the sha256d asics too.<br>
<br>
To reiterate, whether all miners use asicboost or only a subset of<br>
them, I remain unconvinced that provides any additional security to<br>
the network (to be more precise whether that makes &quot;tx history harder<=
br>
to rewrite&quot;), even if it results on the hashrate charts looking &quot;=
more<br>
secure&quot;.<br>
<div class=3D"m_8028033458476356323m_-1831515277159669576m_-649773685898353=
6379HOEnZb"><div class=3D"m_8028033458476356323m_-1831515277159669576m_-649=
7736858983536379h5"><br>
<br>
On Sat, Apr 8, 2017 at 6:27 PM, Jorge Tim=C3=B3n &lt;jtimon@jtimon.cc&gt; w=
rote:<br>
&gt;<br>
&gt;<br>
&gt; On 8 Apr 2017 5:06 am, &quot;Jimmy Song via bitcoin-dev&quot;<br>
&gt; &lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D=
"_blank">bitcoin-dev@lists.linuxfounda<wbr>tion.org</a>&gt; wrote:<br>
&gt;<br>
&gt; Praxeology Guy,<br>
&gt;<br>
&gt;&gt; Why would the actual end users of Bitcoin (the long term and short=
 term<br>
&gt;&gt; owners of bitcoins) who run fully verifying nodes want to change B=
itcoin<br>
&gt;&gt; policy in order to make their money more vulnerable to 51% attack?=
<br>
&gt;<br>
&gt;<br>
&gt; Certainly, if only one company made use of the extra nonce space, they=
 would<br>
&gt; have an advantage. But think of it this way, if some newer ASIC optimi=
zation<br>
&gt; comes up, would you rather have a non-ASICBoosted hash rate to defend =
with<br>
&gt; or an ASICBoosted hash rate? Certainly, the latter, being higher will =
secure<br>
&gt; the Bitcoin network better against newer optimizations.<br>
&gt;<br>
&gt;<br>
&gt; Why?<br>
</div></div></blockquote></div><br></div>
</blockquote></div></div>
</div></div></blockquote></div></div><br></div></div>
</blockquote></div><br></div></div></div>

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