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Subject: Re: [Bitcoin-development] BIP proposal - patch to raise selfish
mining threshold.
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The ratio of honest miners that mine the first block they see is > 0.5
Your proposed solution would reduce that ratio to 0.5
In other words your proposed change would make the attack you describe
easier not harder.
On 11/05/2013 09:26 AM, Ittay wrote:
> That sounds like selfish mining, and the magic number is 25%. That's
> the minimal pool size.
> Today the threshold is 0% with good connectivity.
>
> If I misunderstood your point, please elaborate.
>
> Ittay
>
>
>
> On Tue, Nov 5, 2013 at 12:05 PM, Peter Todd <pete@petertodd.org
> <mailto:pete@petertodd.org>> wrote:
>
> On Tue, Nov 05, 2013 at 11:56:53AM -0500, Ittay wrote:
> > Hello,
> >
> > Please see below our BIP for raising the selfish mining threshold.
> > Looking forward to your comments.
>
> <snip>
>
> > 2. No new vulnerabilities introduced:
> > Currently the choice among equal-length chains is done arbitrarily,
> > depending on network topology. This arbitrariness is a source of
> > vulnerability. We replace it with explicit randomness, which is
> at the
> > control of the protocol. The change does not introduce
> executions that were
> > not possible with the old protocol.
>
> Credit goes to Gregory Maxwell for pointing this out, but the random
> choice solution does in fact introduce a vulnerability in that it
> creates incentives for pools over a certain size to withhold blocks
> rather than immediately broadcasting all blocks found.
>
> The problem is that when the pool eventually choses to reveal the
> block
> they mined, 50% of the hashing power switches, thus splitting the
> network. Like the original attack this can be to their benefit. For
> pools over a certain size this strategy is profitable even without
> investing in a low-latency network; Maxwell or someone else can
> chime in
> with the details for deriving that threshold.
>
> I won't get a chance to for a few hours, but someone should do the
> analysis on a deterministic switching scheme.
>
> --
> 'peter'[:-1]@petertodd.org <http://petertodd.org>
> 0000000000000005e25ca9b9fe62bdd6e8a2b4527ad61753dd2113c268bec707
>
>
>
>
> ------------------------------------------------------------------------------
> November Webinars for C, C++, Fortran Developers
> Accelerate application performance with scalable programming models. Explore
> techniques for threading, error checking, porting, and tuning. Get the most
> from the latest Intel processors and coprocessors. See abstracts and register
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<div class="moz-cite-prefix">The ratio of honest miners that mine
the first block they see is > 0.5<br>
<br>
Your proposed solution would reduce that ratio to 0.5<br>
<br>
In other words your proposed change would make the attack you
describe easier not harder.<br>
<br>
On 11/05/2013 09:26 AM, Ittay wrote:<br>
</div>
<blockquote
cite="mid:CABT1wWnPJOKKT5v2hGePkUT8jNau=TEK5s-n2so2kQKnv-HfqQ@mail.gmail.com"
type="cite">
<div dir="ltr">That sounds like selfish mining, and the magic
number is 25%. That's the minimal pool size.
<div>Today the threshold is 0% with good connectivity. </div>
<div><br>
</div>
<div>If I misunderstood your point, please elaborate. </div>
<div><br>
</div>
<div>Ittay </div>
<div><br>
</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Tue, Nov 5, 2013 at 12:05 PM, Peter
Todd <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:pete@petertodd.org" target="_blank">pete@petertodd.org</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">On Tue, Nov 05, 2013 at 11:56:53AM -0500,
Ittay wrote:<br>
> Hello,<br>
><br>
> Please see below our BIP for raising the selfish
mining threshold.<br>
> Looking forward to your comments.<br>
<br>
</div>
<snip><br>
<div class="im"><br>
> 2. No new vulnerabilities introduced:<br>
> Currently the choice among equal-length chains is
done arbitrarily,<br>
> depending on network topology. This arbitrariness is
a source of<br>
> vulnerability. We replace it with explicit
randomness, which is at the<br>
> control of the protocol. The change does not
introduce executions that were<br>
> not possible with the old protocol.<br>
<br>
</div>
Credit goes to Gregory Maxwell for pointing this out, but
the random<br>
choice solution does in fact introduce a vulnerability in
that it<br>
creates incentives for pools over a certain size to withhold
blocks<br>
rather than immediately broadcasting all blocks found.<br>
<br>
The problem is that when the pool eventually choses to
reveal the block<br>
they mined, 50% of the hashing power switches, thus
splitting the<br>
network. Like the original attack this can be to their
benefit. For<br>
pools over a certain size this strategy is profitable even
without<br>
investing in a low-latency network; Maxwell or someone else
can chime in<br>
with the details for deriving that threshold.<br>
<br>
I won't get a chance to for a few hours, but someone should
do the<br>
analysis on a deterministic switching scheme.<br>
<span class="HOEnZb"><font color="#888888"><br>
--<br>
'peter'[:-1]@<a moz-do-not-send="true"
href="http://petertodd.org" target="_blank">petertodd.org</a><br>
0000000000000005e25ca9b9fe62bdd6e8a2b4527ad61753dd2113c268bec707<br>
</font></span></blockquote>
</div>
<br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">------------------------------------------------------------------------------
November Webinars for C, C++, Fortran Developers
Accelerate application performance with scalable programming models. Explore
techniques for threading, error checking, porting, and tuning. Get the most
from the latest Intel processors and coprocessors. See abstracts and register
<a class="moz-txt-link-freetext" href="http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk">http://pubads.g.doubleclick.net/gampad/clk?id=60136231&iu=/4140/ostg.clktrk</a></pre>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Bitcoin-development mailing list
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</pre>
</blockquote>
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