summaryrefslogtreecommitdiff
path: root/cf/5cf708b763031b69db6f6e7aca20fd23a97204
blob: efe2a93c831d67f8ebcee487b03b51dacc8cf437 (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
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
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 <rme@i-rme.es>) id 1Wt2EG-0002ty-Ew
	for bitcoin-development@lists.sourceforge.net;
	Fri, 06 Jun 2014 22:03:16 +0000
Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of i-rme.es
	designates 209.85.215.52 as permitted sender)
	client-ip=209.85.215.52; envelope-from=rme@i-rme.es;
	helo=mail-la0-f52.google.com; 
Received: from mail-la0-f52.google.com ([209.85.215.52])
	by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128)
	(Exim 4.76) id 1Wt2ED-0005fe-RP
	for bitcoin-development@lists.sourceforge.net;
	Fri, 06 Jun 2014 22:03:14 +0000
Received: by mail-la0-f52.google.com with SMTP id s18so1913251lam.11
	for <bitcoin-development@lists.sourceforge.net>;
	Fri, 06 Jun 2014 15:03:06 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
	d=1e100.net; s=20130820;
	h=x-gm-message-state:mime-version:from:date:message-id:subject:to
	:content-type;
	bh=N1v67UnoqlIwJlvmaRkqh5oAhI5y4vIW/5PScAT8P20=;
	b=RYQGmVqtGTp8BHuIMBxfoG6jbx4SzS9Ib0/etffQJ6lPMBPsEjFsl9q7T+Q3rE4lw7
	As4ka2sTAyE176CisM94IemFL4UR582mZRiBSWDVW2htDU7Gi+jaeVOid/2iE3UpXwHO
	nufwkRIy25qKGCdBfUjA69mm2Ie5mO+r8TAb+Wun0UKnv9lxqU5KM02b+wUE0g8kabAo
	QLGC92gMLJioNxSTSQ5PbjcmwaZIrQHhaUaJE3THuLsYfrUv0RrsQ/lP+xOfAN9ItqVI
	63MGodfIzk5+ucX0PYPpaAHA+7RzAvQEw3SqzupJukUUd5nS5oCYJ6P0lmJqr+sDsqx9
	9BSA==
X-Gm-Message-State: ALoCoQkcmGHtMkHUwkLbve4XaOj5Vp5CvbLpK/sXl5gbPhQn72bJLbwVtsa2TIuC4wk4GoHWGIXa
X-Received: by 10.112.14.5 with SMTP id l5mr5415243lbc.12.1402092186648; Fri,
	06 Jun 2014 15:03:06 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.152.199.8 with HTTP; Fri, 6 Jun 2014 15:02:36 -0700 (PDT)
X-Originating-IP: [85.251.84.81]
From: =?UTF-8?B?UmHDumwgTWFydMOtbmV6?= <rme@i-rme.es>
Date: Sat, 7 Jun 2014 00:02:36 +0200
Message-ID: <CA+8=xu+Bo5W+i__c-QMo+9sTTWzs4mi-wF9FFR1axPPRf5MO1A@mail.gmail.com>
To: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Content-Type: multipart/alternative; boundary=001a11c377d6ba5a3b04fb3206b5
X-Spam-Score: -0.6 (/)
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 SPF_PASS               SPF: sender matches SPF record
	1.0 HTML_MESSAGE           BODY: HTML included in message
	-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: 1Wt2ED-0005fe-RP
Subject: [Bitcoin-development] Possible attack: Keeping unconfirmed
	transactions
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: Fri, 06 Jun 2014 22:03:16 -0000

--001a11c377d6ba5a3b04fb3206b5
Content-Type: text/plain; charset=UTF-8

I dont know if this attack is even possible, it came to my mind and I will
try to explain it as good as possible.

Some transacions keep unconfirmed forever and finally they are purged by
Bitcoin nodes, mostly due to the lack of fees.


Example:
---------

Alice is selling a pizza to Bob, Bob is now making the payment with Bitcoin.
The main goal of this attack is to store a unconfirmed transaction send by
Bob for a few days (it will not be included in the blockchain because it
has no fee or due to other reason), Bob might resend the payment or might
just cancel the deal with Alice.

Bob forgets about that failed trade but a couple of days later, Alice, who
has stored the signed transacion, relays the transaction to the network (or
mines it directly with his own hashpower).
Bob does not know what is happening, he believed that that transaction was
"canceled forever", he even does not remember the failed pizza deal.

Alice has now the bitcoins and Bob does not know what happened with his
money.

---------

This might also work with the Payment Protocol because when using it Bob
does not relay the transaction to the network, its Alices job to do it,
Alice stores it and tells Bob to resend the payment, Bob creates another
transaction (If has the same inputs as the first TX this does not work)
(this one is relayed by Alice to the network).

Alice comes back a couple of days later and mines with his hashrate the
first transaction (the one she didnt relayed to the network).

Alice now has two payments, Bob does not know what happened.


-----------

I hope that I explained well this possible attack, I dont know if there is
already a fix for this problem or if it is simply impossible to execute
this kind of attack.

Thanks for your time.

--001a11c377d6ba5a3b04fb3206b5
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">I dont know if this attack is even possible, it came to my=
 mind and I will try to explain it as good as possible.<div><br></div><div>=
Some transacions keep unconfirmed forever and finally they are purged by Bi=
tcoin nodes, mostly due to the lack of fees.</div>

<div><br></div><div><br></div><div>Example:</div><div>---------</div><div><=
br></div><div>Alice is selling a pizza to Bob, Bob is now making the paymen=
t with Bitcoin.</div><div>The main goal of this attack is to store a unconf=
irmed transaction send by Bob for a few days (it will not be included in th=
e blockchain because it has no fee or due to other reason), Bob might resen=
d the payment or might just cancel the deal with Alice.</div>

<div><br></div><div>Bob forgets about that failed trade but a couple of day=
s later, Alice, who has stored the signed transacion, relays the transactio=
n to the network (or mines it directly with his own hashpower).</div><div>

Bob does not know what is happening, he believed that that transaction was =
&quot;canceled forever&quot;, he even does not remember the failed pizza de=
al.</div><div><br></div><div>Alice has now the bitcoins and Bob does not kn=
ow what happened with his money.</div>

<div><br></div><div>---------</div><div><br></div><div>This might also work=
 with the Payment Protocol because when using it Bob does not relay the tra=
nsaction to the network, its Alices job to do it, Alice stores it and tells=
 Bob to resend the payment, Bob creates another transaction (If has the sam=
e inputs as the first TX this does not work) (this one is relayed by Alice =
to the network).</div>

<div><br></div><div>Alice comes back a couple of days later and mines with =
his hashrate the first transaction (the one she didnt relayed to the networ=
k).</div><div><br></div><div>Alice now has two payments, Bob does not know =
what happened.</div>

<div><br></div><div><br></div><div>-----------</div><div><br></div><div>I h=
ope that I explained well this possible attack, I dont know if there is alr=
eady a fix for this problem or if it is simply impossible to execute this k=
ind of attack.</div>

<div><br></div><div>Thanks for your time.</div><div><br></div><div><br></di=
v><div><br></div><div><br></div></div>

--001a11c377d6ba5a3b04fb3206b5--