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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
Return-Path: <alicexbt@protonmail.com>
Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133])
by lists.linuxfoundation.org (Postfix) with ESMTP id B9126C002A
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 23 May 2023 12:48:11 +0000 (UTC)
Received: from localhost (localhost [127.0.0.1])
by smtp2.osuosl.org (Postfix) with ESMTP id 8DAFC41CF6
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 23 May 2023 12:48:11 +0000 (UTC)
DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 8DAFC41CF6
Authentication-Results: smtp2.osuosl.org;
dkim=pass (2048-bit key) header.d=protonmail.com header.i=@protonmail.com
header.a=rsa-sha256 header.s=protonmail3 header.b=m4PIgCEd
X-Virus-Scanned: amavisd-new at osuosl.org
X-Spam-Flag: NO
X-Spam-Score: -0.103
X-Spam-Level:
X-Spam-Status: No, score=-0.103 tagged_above=-999 required=5
tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1,
DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001,
PDS_OTHER_BAD_TLD=1.999, RCVD_IN_MSPIKE_H2=-0.001,
SPF_HELO_PASS=-0.001, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Received: from smtp2.osuosl.org ([127.0.0.1])
by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024)
with ESMTP id JCBtjNpEx0cF
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 23 May 2023 12:48:10 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0
DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 53BDB40BD5
Received: from mail-4324.protonmail.ch (mail-4324.protonmail.ch [185.70.43.24])
by smtp2.osuosl.org (Postfix) with ESMTPS id 53BDB40BD5
for <bitcoin-dev@lists.linuxfoundation.org>;
Tue, 23 May 2023 12:48:10 +0000 (UTC)
Date: Tue, 23 May 2023 12:48:02 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
s=protonmail3; t=1684846087; x=1685105287;
bh=RW/q+5KEHnmioLd/VFBypll8P8cti3QRjTQjeTNi+44=;
h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References:
Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID:
Message-ID:BIMI-Selector;
b=m4PIgCEdJEbl8EI6MHjXiDZ+lzfrG+qduA10ESUhsk9ql7SUcoTKQ9Ahz64HwWev3
lP2mmvmgpmj86aBgYExR+kY3oOfbPMO+JpDQq9/zHsODrL4XTv9ElHaTzlQTaZey/R
vxE9Nu+ZnqDDirbLh7IWARu6inDY/Sl5Y8LOFXCLeADeOMxunJH7+DPKL6olcvdLJ7
MRt3tjoD4FY4F4VbVGxDnfiMxySsQnQQwTK7jYzA87LEgbYLIITEMWe4q7CuIcYeVo
QNMZoBeuA3es8iRprlrJVu1Y8S3Am1aLyVDxROAlx9j9ekFbrVMMXRGgzIhUX70xiB
bGfken0ZZWN5g==
To: Lucas Ontivero <lucasontivero@gmail.com>
From: alicexbt <alicexbt@protonmail.com>
Message-ID: <oLOjKr_MJ2WHkg0KSM5sw5B9RQNFDWpM3RHjea_Q_lRM3rBzwyRELllZzc2hxuGjFTkykJDAP1p-p3QbXTqYMl3U_EnuDxq_3a5ZfcB7aPw=@protonmail.com>
In-Reply-To: <CALHvQn29S2T=ehqGD1vCJQQuC0aD6rjUUPsb+n80EBPgc_G4JA@mail.gmail.com>
References: <EWAXAmgFlZ8XQJOYO8VTH7Zj0tTAftwy-ylaGvf3Giealz1FFb97CbcxjP0q-Zu85XoAzOG0ivdYIKa_kG77ooHqBvCP7YOZOkb6yHmX75s=@protonmail.com>
<SJ1P223MB0531D7D62140F0516A25897AA1439@SJ1P223MB0531.NAMP223.PROD.OUTLOOK.COM>
<CALHvQn29S2T=ehqGD1vCJQQuC0aD6rjUUPsb+n80EBPgc_G4JA@mail.gmail.com>
Feedback-ID: 40602938:user:proton
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
X-Mailman-Approved-At: Tue, 23 May 2023 13:04:22 +0000
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Coinjoin with less steps using ALL|ANYONECANPAY
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Bitcoin Protocol Discussion <bitcoin-dev.lists.linuxfoundation.org>
List-Unsubscribe: <https://lists.linuxfoundation.org/mailman/options/bitcoin-dev>,
<mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=unsubscribe>
List-Archive: <http://lists.linuxfoundation.org/pipermail/bitcoin-dev/>
List-Post: <mailto:bitcoin-dev@lists.linuxfoundation.org>
List-Help: <mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=help>
List-Subscribe: <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>,
<mailto:bitcoin-dev-request@lists.linuxfoundation.org?subject=subscribe>
X-List-Received-Date: Tue, 23 May 2023 12:48:11 -0000
Hi Lucas,
> In some coinjoin implementations inputs are registered first because in t=
hat way, if the user fails or refuses to sign the transaction the input is =
banned and denial of service is made a bit more expensive, in the sense tha=
t an attacker needs more and more utxos to keep the attack going.
DoS attacks are even possible in later stages of a coinjoin round. Example:=
Double spend inputs after signing
Inputs could be banned in second step if ALL|ANYONECANPAY sighash flag is u=
sed and outputs are registered initially.
/dev/fd0
floppy disk guy
Sent with Proton Mail secure email.
------- Original Message -------
On Tuesday, May 23rd, 2023 at 5:47 PM, Lucas Ontivero <lucasontivero@gmail.=
com> wrote:
> Hi all,
> In some coinjoin implementations inputs are registered first because in t=
hat way, if the user fails or refuses to sign the transaction the input is =
banned and denial of service is made a bit more expensive, in the sense tha=
t an attacker needs more and more utxos to keep the attack going.
>=20
> Your proposal can work if you find an alternative mechanism for mitigatin=
g the DoS attacks or when DoS attacks are not a problem (I can imagine ther=
e are scenarios where it is not really important).
> Best
> - Lucas
>=20
>=20
>=20
> On Mon, May 22, 2023 at 7:53=E2=80=AFPM Ben Carman via bitcoin-dev <bitco=
in-dev@lists.linuxfoundation.org> wrote:
>=20
> > The problem with using ALL|ANYONECANPAY is that you cannot verify befor=
ehand that the other inputs are the inputs you want added to the transactio=
n.
> >=20
> > Some examples of bad things that could happen:
> >=20
> >=20
> > - Coordinator adds its own inputs, you still get your outputs but eff=
ectively paid fees for no privacy gain
> > - The inputs added could be paying at a lower fee rate than expected,=
causing the tx to take longer than what you paid for
> > - Different input types or amount are added so you no longer have the=
same uniformity across the inputs
> > - (if you care) An input from a sanctioned address is added, causing =
you to get "tainted" coins.
> > =20
> >=20
> > This is the code in ln-vortex that verifies the psbt on the client side=
if you are curious
> >=20
> > https://github.com/ln-vortex/ln-vortex/blob/master/client/src/main/scal=
a/com/lnvortex/client/VortexClient.scala#L616
> >=20
> >=20
> > Best,
> >=20
> > benthecarman
> >=20
> >=20
> >=20
> > From: bitcoin-dev <bitcoin-dev-bounces@lists.linuxfoundation.org> on be=
half of alicexbt via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
> > Sent: Monday, May 22, 2023 7:51 AM
> > To: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
> > Subject: [bitcoin-dev] Coinjoin with less steps using ALL|ANYONECANPAY
> >=20
> > Hi Bitcoin Developers,
> >=20
> > I recently experimented with different sighash flags, PSBTs and realize=
d ALL|ANYONECANPAY could be used to reduce some steps in coinjoin.
> >=20
> > Steps:
> >=20
> > - Register outputs.
> > - One user creates a signed PSBT with 1 input, all registered outputs a=
nd ALL|ANYONECANPAY sighash flag. Other participants keep adding their inpu=
ts to PSBT.
> > - Finalize and broadcast the transaction.
> >=20
> > Proof of Concept (Aice and Bob): https://gitlab.com/-/snippets/2542297
> >=20
> > Tx: https://mempool.space/testnet/tx/c6dd626591dca7e25bbd516f01b23171eb=
0f2b623471fcf8e073c87c1179c492
> >=20
> > I plan to use this in joinstr if there are no major drawbacks and it ca=
n even be implemented by other coinjoin implementations.
> >=20
> > /dev/fd0
> > floppy disk guy
> >=20
> > Sent with Proton Mail secure email.
> > _______________________________________________
> > bitcoin-dev mailing list
> > bitcoin-dev@lists.linuxfoundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >=20
> > _______________________________________________
> > bitcoin-dev mailing list
> > bitcoin-dev@lists.linuxfoundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
|
