summaryrefslogtreecommitdiff
path: root/cf/f9d6864e08e938f6fc46cb59b1ecc2220a3706
blob: b8aef07e0550e2c0b24547c8463ea80ab553041c (plain)
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
Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191]
	helo=mx.sourceforge.net)
	by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
	(envelope-from <colj@Safe-mail.net>) id 1VdnbF-0006Ac-J6
	for Bitcoin-development@lists.sourceforge.net;
	Tue, 05 Nov 2013 20:51:45 +0000
Received: from tapuz.safe-mail.net ([213.8.161.230])
	by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256)
	(Exim 4.76) id 1Vdnb4-0007aX-0m
	for Bitcoin-development@lists.sourceforge.net;
	Tue, 05 Nov 2013 20:51:45 +0000
Received: by tapuz.safe-mail.net with Safe-mail (Exim 4.63)
	(envelope-from <colj@Safe-mail.net>) id 1Vdnau-0004Vf-5i
	for Bitcoin-development@lists.sourceforge.net;
	Tue, 05 Nov 2013 15:51:24 -0500
Received: from pc ([37.221.160.203]) by Safe-mail.net with https
Date: Tue, 5 Nov 2013 15:51:24 -0500
From: colj@Safe-mail.net
To: Bitcoin-development@lists.sourceforge.net
X-SMType: Regular
X-SMRef: N1-9eAtMHauq2
Message-Id: <N1-9eAtMHauq2@Safe-mail.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: quoted-printable
X-SMSignature: lw8fbDC924d2oC6n83J8tMlQ+NXG+UjHuVS6sDBhKlYlciw5BIXz54FX1msnmgVX
	JCpzftsuvVvcn+gJ0jJWVh+Q22K2ULriaAfnDlWcqhbfWqUo8n/cnHco3kJRViih
	67epjLLhP14YmWxShs1ZZ3NJvDmdNBFb4JS0cWdvsBs=
X-Spam-Score: -0.1 (/)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
	See http://spamassassin.org/tag/ for more details.
	0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider
	(colj[at]safe-mail.net)
	-0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay
	domain
	0.0 URIBL_BLOCKED ADMINISTRATOR NOTICE: The query to URIBL was blocked.
	See
	http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block
	for more information. [URIs: safe-mail.net]
	0.0 MIME_QP_LONG_LINE RAW: Quoted-printable line longer than 76 chars
	-0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from
	author's domain
	0.1 DKIM_SIGNED            Message has a DKIM or DK signature,
	not necessarily valid
	-0.1 DKIM_VALID Message has at least one valid DKIM or DK signature
X-Headers-End: 1Vdnb4-0007aX-0m
Subject: [Bitcoin-development] Possible Solution To SM Attack
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: Tue, 05 Nov 2013 20:51:45 -0000

Preliminary:
Alice has the ability to hear of a block before all other miners do.

The Problem:
Say Alice built a block, A1, from previous block 0. She doesn't let other miners =
know about it. She then works on A2 with previous block A1. Bob on the other =
hand is still working on B1 with previous block 0. Bob now finds a block and =
he broadcasts it. The assumption here is Alice will be the first miner to hear =
of this block and she will send her previously mined block, A1, to all other =
miners. By the time Bobs block arrives to other miners majority of them will =
already have received Block A1 and Bobs block will most likely be orphaned. =
Alice revealed her block, A1, only when Bob broadcast his block. This means =
she has been mining on block A2 with previous block A1 for longer than any =
other miner thus gaining an advantage without increasing her hash rate.

What We Know:
Alice has gained an advantage with time. She mines longer on the valid block.
In order for this attack to work Alice must reveal her previously mined block =
as late as possible, gaining her the most time spent working on the valid block. =
Since she has such good view of the Bitcoin network she can wait until a miner =
finds a block to release her previously mined block.

The most obvious sign of this attack taking place is the timing. A miner will =
receive a block and very quickly hear of another block both built from the =
same previous block. 

The block that a miner hears first is the one which will be mined on.

Possible Solution:
If N amount of blocks built of the same previous block are received within =
a time frame of T mine on the block with the lowest hash.

Logic:
In order for Alice to pull of this attack she not only has to propagate her =
blocks first she must also ensure her blocks are of the smallest hash.

Alice would now have to decrease her target to pull of this attack. Since she =
has a lower target it will take her longer to find a valid block negating her =
time advantage.


colj