From: Peter Todd <pete@petertodd•org>
To: Luke-Jr <luke@dashjr•org>
Cc: bitcoin-development@lists•sourceforge.net
Subject: Re: [Bitcoin-development] The insecurity of merge-mining
Date: Tue, 31 Dec 2013 23:53:42 -0500 [thread overview]
Message-ID: <20140101045342.GA7103@tilt> (raw)
In-Reply-To: <201312310114.05600.luke@dashjr.org>
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On Tue, Dec 31, 2013 at 01:14:05AM +0000, Luke-Jr wrote:
> On Monday, December 30, 2013 11:22:25 PM Peter Todd wrote:
> > that you are using merge-mining is a red-flag because without majority, or
> > at least near-majority, hashing power an attacker can 51% attack your
> > altcoin at negligible cost by re-using existing hashing power.
>
> I strongly disagree on this isolated point. Using the same logic, Bitcoin is
> vulnerable to an attacker at negligible cost by re-using existing hashing
> power from mining Namecoin. Any non-scam altcoin is pretty safe using merged
> mining, since any would-be attacker is going to have it in their interests to
> invest in the altcoin instead of attacking it. It's only the scam ones that
> want to pump & dump with no improvements, that are really at risk here.
>
> The rational decision for a non-scam altcoin, is to take advantage of merged
> mining to get as much security as possible. There are also some possible
> tricks to get the full security of the bitcoin miners even when not all
> participate in your altcoin (but this area probably needs some studying to get
> right).
You assume the value of a crypto-currency is equal to all miners, it's
not.
Suppose I create a merge-mined Zerocoin implementation with a 1:1
BTC/ZTC exchange rate enforced by the software. You can't argue this is
a scamcoin; no-one is getting rich. There's a 1:1 exchange rate so the
only thing you can do with the coin is get some privacy. But inevitably
some miners won't agree that enabling better privacy is a good thing, or
their local governments won't. Either way, they can attack the Zerocoin
merge-mined chain with a marginal cost of nearly zero.
OTOH if the Zerocoin scheme was implemented by embedding ZTC
transactions within standard Bitcoin transactions - even without any
attempt at hiding them - the attackers would need a 50% majority of
hashing power to succeed. Of course potentially slow confirmations is a
trade-off, but that's likely a perfectly OK trade-off in this case.
--
'peter'[:-1]@petertodd.org
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next prev parent reply other threads:[~2014-01-01 4:54 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-29 18:53 [Bitcoin-development] Looking for GREAT C++ developer for exciting opportunity in bitcoin space Evan Duffield
2013-12-29 19:27 ` Matt Corallo
2013-12-30 23:22 ` Peter Todd
2013-12-31 1:14 ` Luke-Jr
2013-12-31 7:28 ` [Bitcoin-development] Merge mining Jeremy Spilman
2013-12-31 7:38 ` rob.golding
2014-01-04 8:49 ` David Vorick
2014-01-04 10:05 ` Jorge Timón
2014-01-04 10:08 ` David Vorick
2014-01-04 10:34 ` Jorge Timón
2014-01-01 4:53 ` Peter Todd [this message]
2014-01-01 5:09 ` [Bitcoin-development] The insecurity of merge-mining Luke-Jr
2014-01-01 5:25 ` Peter Todd
2014-01-03 19:14 ` Jorge Timón
2014-01-03 21:01 ` Peter Todd
2014-01-04 0:27 ` Jorge Timón
2014-01-06 15:44 ` Peter Todd
2014-01-09 17:19 ` Jorge Timón
2014-01-10 11:11 ` Peter Todd
2014-01-10 11:25 ` Peter Todd
2014-01-10 12:37 ` Jorge Timón
2014-01-10 12:29 ` Jorge Timón
2014-01-10 17:22 ` Peter Todd
2014-01-10 18:50 ` Jorge Timón
2014-01-03 5:11 ` [Bitcoin-development] Looking for GREAT C++ developer for exciting opportunity in bitcoin space Troy Benjegerdes
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