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
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
|
Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192]
helo=mx.sourceforge.net)
by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
(envelope-from <bitcoin-list@bluematt.me>) id 1S2sAA-0002hg-28
for bitcoin-development@lists.sourceforge.net;
Wed, 29 Feb 2012 22:38:22 +0000
Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of bluematt.me
designates 173.246.101.161 as permitted sender)
client-ip=173.246.101.161;
envelope-from=bitcoin-list@bluematt.me; helo=mail.bluematt.me;
Received: from vps.bluematt.me ([173.246.101.161] helo=mail.bluematt.me)
by sog-mx-2.v43.ch3.sourceforge.com with esmtp (Exim 4.76)
id 1S2sA8-0002RH-Cc for bitcoin-development@lists.sourceforge.net;
Wed, 29 Feb 2012 22:38:21 +0000
Received: from [152.23.98.43] (dhcp04615.highsouth-resnet.unc.edu
[152.23.98.43])
by mail.bluematt.me (Postfix) with ESMTPSA id E722EEE4
for <bitcoin-development@lists.sourceforge.net>;
Wed, 29 Feb 2012 22:37:08 +0000 (UTC)
From: Matt Corallo <bitcoin-list@bluematt.me>
To: bitcoin-development@lists.sourceforge.net
In-Reply-To: <CAPBPUnqgV_hHYwFoB_1qXMvEaE1pM0vm8=V=AKe2n-rPFzz+mQ@mail.gmail.com>
References: <CAPg+sBhb+gYMwp1OJuCHYt5=BU63=YBWOFaLLthHBkN_U-scaA@mail.gmail.com>
<CAPBPUnqgV_hHYwFoB_1qXMvEaE1pM0vm8=V=AKe2n-rPFzz+mQ@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Date: Wed, 29 Feb 2012 17:38:13 -0500
Message-ID: <1330555093.3202.2.camel@BMThinkPad.lan.bluematt.me>
Mime-Version: 1.0
X-Mailer: Evolution 2.32.2
Content-Transfer-Encoding: 7bit
X-Spam-Score: -1.4 (-)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
See http://spamassassin.org/tag/ for more details.
-1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for
sender-domain
-0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay
domain
-0.0 SPF_PASS SPF: sender matches SPF record
0.1 AWL AWL: From: address is in the auto white-list
X-Headers-End: 1S2sA8-0002RH-Cc
Subject: Re: [Bitcoin-development] Duplicate transactions vulnerability
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, 29 Feb 2012 22:38:22 -0000
In other words when we roll out the update, we have to make sure we have
>>50% not just 50%. Something like 60%-75% should do fine (IMHO). In
other words we just have to be very, very vocal about the change when it
happens and make sure miners are all on board.
Matt
On Wed, 2012-02-29 at 22:05 +0000, Ben Reeves wrote:
> Assuming 50% of hashing power adopts BIP30 but the actual client
> install base is relatively low the patch will likely result in a
> "hard" blockchain split if someone takes advantage.
>
> A malicious miner can produce a duplicate coinbase which the majority
> of clients will accept but the majority of hashing power won't.
> Spending the coinbase output after disconnection will cause the
> blockchain to fork. All none BIP30 clients on the short blockchain
> will be vulnerable to transaction reversal of 6 confirmations or more.
>
> It is a relatively inexpensive attack to perform (costing the attacker
> only one valid block ~$240) and could be quite disruptive. I think
> this should be patched in DisconnectBlock() (if it hasn't already?)
> before any protocol change - maybe a new mapByCoinbase multimap is
> needed.
>
> Thank You,
> Ben Reeves
> www.blockchain.info
>
> On Tue, Feb 28, 2012 at 4:48 PM, Pieter Wuille <pieter.wuille@gmail.com> wrote:
> > Hello all,
> >
> > as some of you may know, a vulnerability has been found in how the
> > Bitcoin reference client deals with duplicate transactions. Exploiting
> > it is rather complex, requires some hash power, and has no financial
> > benefit for the attacker. Still, it's a security hole, and we'd like
> > to fix this as soon as possible.
> >
> > A simple way to fix this, is adding an extra protocol rule[1]:
> >
> > Do not allow blocks to contain a transaction whose hash is equal to
> > that of a former transaction which has not yet been completely spent.
> >
> > I've written about it in BIP30[2]. There is a patch for the reference
> > client, which has been tested and verified to make the attack
> > impossible. The change is backward compatible in the same way BIP16
> > is: if a supermajority of mining power implements it, old clients can
> > continue to function without risk.
> >
> > The purpose of this mail is asking for support for adding this rule to
> > the protocol rules. If there is consensus this rule is the solution, I
> > hope pools and miners can agree to update their nodes without lengthy
> > coinbase-flagging procedure that would only delay a solution. So, who
> > is in favor?
> >
> > [1] https://en.bitcoin.it/wiki/Protocol_rules
> > [2] https://en.bitcoin.it/wiki/BIP_0030
> >
> > --
> > Pieter
|
