1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194]
helo=mx.sourceforge.net)
by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
(envelope-from <luke@dashjr.org>) id 1VyE3n-0007uq-DY
for bitcoin-development@lists.sourceforge.net;
Wed, 01 Jan 2014 05:09:39 +0000
X-ACL-Warn:
Received: from zinan.dashjr.org ([192.3.11.21])
by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76)
id 1VyE3m-0003r0-Gb for bitcoin-development@lists.sourceforge.net;
Wed, 01 Jan 2014 05:09:39 +0000
Received: from ishibashi.localnet (unknown
[IPv6:2001:470:5:265:be5f:f4ff:febf:4f76])
(Authenticated sender: luke-jr)
by zinan.dashjr.org (Postfix) with ESMTPSA id DB5A110837A7;
Wed, 1 Jan 2014 05:09:48 +0000 (UTC)
From: "Luke-Jr" <luke@dashjr.org>
To: Peter Todd <pete@petertodd.org>
Date: Wed, 1 Jan 2014 05:09:27 +0000
User-Agent: KMail/1.13.7 (Linux/3.12.6-gentoo; KDE/4.11.2; x86_64; ; )
References: <CAMkFLsSwKEiEtV1OaAsGPiU8iAWbb77fDNJDmRwbgKnZ_kjG6Q@mail.gmail.com>
<201312310114.05600.luke@dashjr.org> <20140101045342.GA7103@tilt>
In-Reply-To: <20140101045342.GA7103@tilt>
X-PGP-Key-Fingerprint: E463 A93F 5F31 17EE DE6C 7316 BD02 9424 21F4 889F
X-PGP-Key-ID: BD02942421F4889F
X-PGP-Keyserver: hkp://pgp.mit.edu
MIME-Version: 1.0
Content-Type: Text/Plain;
charset="iso-8859-15"
Content-Transfer-Encoding: 7bit
Message-Id: <201401010509.27977.luke@dashjr.org>
X-Spam-Score: -0.1 (/)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
See http://spamassassin.org/tag/ for more details.
-0.1 RP_MATCHES_RCVD Envelope sender domain matches handover relay
domain
X-Headers-End: 1VyE3m-0003r0-Gb
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] The insecurity of merge-mining
X-BeenThere: bitcoin-development@lists.sourceforge.net
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: <bitcoin-development.lists.sourceforge.net>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development>
List-Post: <mailto:bitcoin-development@lists.sourceforge.net>
List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe>
X-List-Received-Date: Wed, 01 Jan 2014 05:09:39 -0000
On Wednesday, January 01, 2014 4:53:42 AM Peter Todd wrote:
> 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.
Not necessarily. If Zerocoin was tied directly to Bitcoin proof-of-work, the
worst they could do is not-participate by mining empty blocks.
> 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.
Potentially slow confirmation is also the only shortcoming of using Bitcoin's
proof-of-work directly.
Luke
|
