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From: Daniele Pinna <daniele.pinna@gmail.com>
Date: Sun, 11 Dec 2016 04:17:45 +0100
Message-ID: <CAEgR2PEuZBZqUJ-qehBpk8dL8U-F5z9mZAn-UuRwUXiUSOcXRQ@mail.gmail.com>
To: Pieter Wuille <pieter.wuille@gmail.com>
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Subject: Re: [bitcoin-dev] Managing block size the same way we do difficulty
(aka Block75)
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--001a114134526322a70543596e50
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How is the adverse scenario you describe different from a plain old 51%
attack? Each proposed protocol change where 51% or more of the network
can potentially game the rules and break the system should be considered
just as acceptable/unacceptable as another.
There comes a point where some form of basic honesty must be assumed on
behalf of participants benefiting from the system working properly and
reliably.
Afterall, what magic line of code prohibits all miners from simultaneously
turning all their equipment off... just because?
Maybe this 'one':
"As long as a majority of CPU power is controlled by nodes that are not
cooperating to attack the network, they'll generate the longest chain and
outpace attackers. The network itself requires minimal structure."
Is there such a thing as an unrecognizable 51% attack? One where the
remaining 49% get dragged in against their will?
Daniele
On Dec 10, 2016 6:39 PM, "Pieter Wuille" <pieter.wuille@gmail.com> wrote:
> On Sat, Dec 10, 2016 at 4:23 AM, Daniele Pinna via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
>> We have models for estimating the probability that a block is orphaned
>> given average network bandwidth and block size.
>>
>> The question is, do we have objective measures of these two quantities?
>> Couldn't we target an orphan_rate < max_rate?
>>
>
> Models can predict orphan rate given block size and network/hashrate
> topology, but you can't control the topology (and things like FIBRE hide
> the effect of block size on this as well). The result is that if you're
> purely optimizing for minimal orphan rate, you can end up with a single
> (conglomerate of) pools producing all the blocks. Such a setup has no
> propagation delay at all, and as a result can always achieve 0 orphans.
>
> Cheers,
>
> --
> Pieter
>
>
--001a114134526322a70543596e50
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
<div dir=3D"auto">How is the adverse scenario you describe different from a=
plain old 51% attack? Each proposed protocol change =C2=A0where 51% or mor=
e =C2=A0of the network can potentially game the rules and break the system =
should be considered just as acceptable/unacceptable as another.=C2=A0<div =
dir=3D"auto"><br></div><div dir=3D"auto">There comes a point where some for=
m of basic honesty must be assumed on behalf of participants benefiting fro=
m the system working properly and reliably.=C2=A0</div><div dir=3D"auto"><b=
r></div><div dir=3D"auto">Afterall, what magic line of code prohibits all m=
iners from simultaneously turning all their equipment off... =C2=A0just bec=
ause?=C2=A0</div><div dir=3D"auto"><br></div><div dir=3D"auto">Maybe this &=
#39;one':</div><div dir=3D"auto"><br></div><div dir=3D"auto">"As l=
ong as a majority of CPU power is controlled by nodes that are not cooperat=
ing to attack the network, they'll generate the longest chain and outpa=
ce attackers. The network itself requires minimal structure."</div><di=
v dir=3D"auto"><br></div><div dir=3D"auto">Is there such a thing as an unre=
cognizable 51% attack?=C2=A0 One where the remaining 49% get dragged in aga=
inst their will?=C2=A0</div><div dir=3D"auto"><br></div><div dir=3D"auto">D=
aniele=C2=A0</div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_=
quote">On Dec 10, 2016 6:39 PM, "Pieter Wuille" <<a href=3D"ma=
ilto:pieter.wuille@gmail.com">pieter.wuille@gmail.com</a>> wrote:<br typ=
e=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">On Sat, D=
ec 10, 2016 at 4:23 AM, Daniele Pinna via bitcoin-dev <span dir=3D"ltr"><=
;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank"=
>bitcoin-dev@lists.linuxfounda<wbr>tion.org</a>></span> wrote:<br><div c=
lass=3D"gmail_extra"><div class=3D"gmail_quote"><blockquote class=3D"gmail_=
quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1=
ex"><div dir=3D"auto"><div dir=3D"auto"><span style=3D"font-size:13.696px;f=
ont-family:sans-serif">We have models for estimating the probability that a=
block is orphaned given average network bandwidth and block size.=C2=A0</s=
pan><br></div><div dir=3D"auto"><span style=3D"font-size:13.696px;font-fami=
ly:sans-serif"><br></span></div><div dir=3D"auto"><span style=3D"font-famil=
y:sans-serif;font-size:13.696px">The question is, do we have objective meas=
ures of these two quantities? Couldn't we target an orphan_rate < ma=
x_rate?=C2=A0</span><span style=3D"font-size:13.696px;font-family:sans-seri=
f"><br></span></div></div></blockquote><div><br></div><div>Models can predi=
ct orphan rate given block size and network/hashrate topology, but you can&=
#39;t control the topology (and things like FIBRE hide the effect of block =
size on this as well). The result is that if you're purely optimizing f=
or minimal orphan rate, you can end up with a single (conglomerate of) pool=
s producing all the blocks. Such a setup has no propagation delay at all, a=
nd as a result can always achieve 0 orphans.<br><br></div><div>Cheers,<br><=
br>-- <br></div><div>Pieter<br><br></div></div></div></div>
</blockquote></div></div>
--001a114134526322a70543596e50--
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