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Date: Mon, 08 Apr 2013 07:32:30 -0500
From: Daryl Tucker <daryl@daryltucker.com>
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Subject: Re: [Bitcoin-development] A mining pool at 46%
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BTC Guild's response:

51% Mitigation Plan
I want to start by thanking all users, new and old, for making BTC
Guild become what it is today. I never expected a service that
originally started on a mining PC in my dining room in April 2011 to
go this far.

However, recently BTC Guild has started to become "too big". Users of
Bitcoin are becoming scared that BTC Guild, either directly or through
hacking/coercion, could be used to attack the network as it gets
closer to 51% of the network. If this were to happen, it is likely
many people would lose confidence in Bitcoin, as a single entity could
control the network if it wanted to do so.

I have put forward a proposal of my plans on how to mitigate this
threat, but unfortunately nothing can be done without users taking
some initiative as well. The following are the actions that will be
taken if certain thresholds are crossed:


More than 40% of the Network [last 2016 blocks]
PPS fee will be raised from 5% to 7% on all new accounts. Old accounts
will also be increased (PPS ONLY) to 7% after a difficulty change. If
the pool eventually drops back under 40% for more than 72 hours, these
fees will be turned back down to 5% after the next difficulty change.

More than 45% of the Network [last 2016 blocks]
Getwork based pools will be completely removed within 24 hours. All
users on getwork have been warned in the past that it is a unsupported
and not advised method of connecting. This should remove ~15% of BTC
Guild's hash rate immediately.

More than 40% of the Network again [last 2016 blocks]
PPLNS fee will be raised from 3% to 4% after a 72 hour warning. This
fee will be reduced back to 3% once the pool drops back under 40% for
more than 72 hours.


If you have questions or comments, please leave them on the forum
thread related to this issue:
https://bitcointalk.org/index.php?topic=168108.0


https://www.btcguild.com/index.php?page=home


On 04/05/2013 07:12 AM, Peter Todd wrote:
> On Fri, Apr 05, 2013 at 12:13:23PM +0200, Melvin Carvalho wrote:
>> Totally see the logic of this, and it makes sense.  But I dont
>> think the only risk is in terms of double spend, but rather
>> 
>> 1) vandalize the block chain which may be difficult to unwind?
> 
> Vandalize the chain how? By delibrately triggering bugs? (like the
> old OP_CHECKSIG abuse problem) Regardless of whether or not the 
> vulnerability requires multiple blocks in a row, the underlying
> problem should be fixed.
> 
> By putting illegal data into it? Fundementally we have no way to
> prevent people from doing that other than by making it expensive.
> An attacker having a lot of hashing power just means they can do so
> faster and a bit cheaper.
> 
> 
> 
> ------------------------------------------------------------------------------
>
> 
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> _______________________________________________ Bitcoin-development
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> 

-- 

Daryl Tucker
daryl@daryltucker.com