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
|
Return-Path: <ZmnSCPxj@protonmail.com>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
[172.17.192.35])
by mail.linuxfoundation.org (Postfix) with ESMTPS id 480DBBE4
for <bitcoin-dev@lists.linuxfoundation.org>;
Mon, 9 Sep 2019 04:14:17 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from mail-40133.protonmail.ch (mail-40133.protonmail.ch
[185.70.40.133])
by smtp1.linuxfoundation.org (Postfix) with ESMTPS id C058D6D6
for <bitcoin-dev@lists.linuxfoundation.org>;
Mon, 9 Sep 2019 04:14:15 +0000 (UTC)
Date: Mon, 09 Sep 2019 04:14:07 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
s=default; t=1568002452;
bh=SLZZp1tC0Ua8GgW8/GsV0bSuzEDcPtFzqk1K1GlyCFU=;
h=Date:To:From:Reply-To:Subject:In-Reply-To:References:Feedback-ID:
From;
b=OdcFmZc82QulfJ0qVCJTzefQJohCrk/1R7KmtvapzbfbAde7U24NDVDJUnr0E9VMt
PLcnvDZPR/12Vuk0dZYZF7ZSaRNSoSfctWaboVpVwXl4+O9crw6taX9xq8dQZko6XW
zcBRTa8ZTEQyE/uzN79iZInG+iohKbQz2QayvFO8=
To: Ruben Somsen <rsomsen@gmail.com>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Reply-To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Message-ID: <uVQNn9hhpqlQuS-RzrUkpClVtegMRUoyIL6ITaYfNkjd_XYyu9Fh9vdAeLguzOyOrNx5FtuHk7yyZAdivqCVR2PKzF_PsoWJlsSY9oJTF7s=@protonmail.com>
In-Reply-To: <CAPv7TjaE1wF-25R=LaOES33A78ovDAp9-waiC7n5YLJnMmNs9A@mail.gmail.com>
References: <CAPv7TjaE1wF-25R=LaOES33A78ovDAp9-waiC7n5YLJnMmNs9A@mail.gmail.com>
Feedback-ID: el4j0RWPRERue64lIQeq9Y2FP-mdB86tFqjmrJyEPR9VAtMovPEo9tvgA0CrTsSHJeeyPXqnoAu6DN-R04uJUg==:Ext:ProtonMail
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,
DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, FROM_LOCAL_NOVOWEL,
RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1
X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on
smtp1.linux-foundation.org
Subject: Re: [bitcoin-dev] PoW fraud proofs without a soft fork
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.12
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: Mon, 09 Sep 2019 04:14:17 -0000
Good morning Ruben,
> One might intuitively feel that the lack of a commitment is unsafe,
> but there seems to be no impact on security (only bandwidth). The onl=
y
> way you can be fooled is if all peers lie to you (Sybil), causing you
> to follow a malicious minority chain. But even full nodes (or the
> committed version of PoW fraud proofs) can be fooled in this way if
> they are denied access to the valid most PoW chain. If there are
> additional security concerns I overlooked, I=E2=80=99d love to hear t=
hem.
I think it would be better to more precisely say that:
1. In event of a sybil attack, a fullnode will stall and think the blockch=
ain has no more miners.
2. In event of a sybil attack, an SPV, even using this style, will follow =
the false blockchain.
This has some differences when considering automated systems.
Onchain automated payment processing systems, which use a fullnode, will re=
fuse to acknowledge any incoming payments.
This will lead to noisy complaints from clients of the automated payment pr=
ocessor, but this is a good thing since it warns the automated payment proc=
essor of the possibility of this attack occurring on them.
The use of a timeout wherein if the fullnode is unable to see a new block f=
or, say, 6 hours, could be done, to warn higher-layer management systems to=
pay attention.
While it is sometimes the case that the real network will be unable to find=
a new block for hours at a time, this warning can be used to confirm if su=
ch an event is occurring, rather than a sybil attack targeting that fullnod=
e.
On the other hand, such a payment processing system, which uses an SPV with=
PoW fraud proofs, will be able to at least see incoming payments, and cont=
inue to release product in exchange for payment.
Yet this is precisely a point of attack, where the automated payment proces=
sing system is sybilled and then false payments are given to the payment pr=
ocessor on the attack chain, which are double-spent on the global consensus=
chain.
And the automated system may very well not be able to notice this.
Regards,
ZmnSCPxj
|
