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
|
Return-Path: <orlovsky@protonmail.com>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
[172.17.192.35])
by mail.linuxfoundation.org (Postfix) with ESMTPS id D9FC2C91
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 21 Aug 2019 17:04:45 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from mail-40132.protonmail.ch (mail-40132.protonmail.ch
[185.70.40.132])
by smtp1.linuxfoundation.org (Postfix) with ESMTPS id EAE81E6
for <bitcoin-dev@lists.linuxfoundation.org>;
Wed, 21 Aug 2019 17:04:44 +0000 (UTC)
Date: Wed, 21 Aug 2019 17:04:35 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
s=default; t=1566407082;
bh=ZIeXs16tsQ2EJ1em04gU8sPPqFV7AkcujzC8NNZtH+E=;
h=Date:To:From:Cc:Reply-To:Subject:In-Reply-To:References:
Feedback-ID:From;
b=Cn5Wr8s9YqAPzr/7RwBYkKrV8ltiifAf8UJJeQSAXyo8y14eoisHMJjoHccrGGl+Y
CiwVPL1IGaWBMJRh7VUM8H2QDvN14Bw1oua+eza08BXa0uBikgcWjrOGc/WLEJAP0y
oYHI0V2GwgwaFDm9P0GOoyjLleiQle8XvUnRAwkI=
To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
From: Dr Maxim Orlovsky <orlovsky@protonmail.com>
Reply-To: Dr Maxim Orlovsky <orlovsky@protonmail.com>
Message-ID: <yBkmyGw473TegSTQPwap9mH7xT4yHWeFBAuq7Whztr56CPIMeN4Ld0edRg9uGnvTGhUy_GML8pM9XHnIHPxBc4Cv0MVejhlclbC_6eMFsKI=@protonmail.com>
In-Reply-To: <x1b18QXzxALwxxp8ehwcB7XORizrw5vOJ9BNXWpXbd2SJgUra-AFIyTgnM_yxKEtCg_frZcz916NLmm-pTsCD4Z7aOFprdQ_W87mHnn8vYg=@protonmail.com>
References: <GJgJhEIXm9MyKb_3kGCd2RdvkVQGHjJIE_lCHtp5hQUt7lHvYl1lXTfgyGwwVC0w9LfeZBf86XEbU694V0EdDrB0HwXa7dMhxD7m5MSUI-g=@protonmail.com>
<6o-9VFKLR0h4CUf_fUN1rAqwTTZMlxk2CwwHSbuuvesIapG8ySj4KyHyUmHRh8rf7Lc2urCX8vw7tmlkP60SfvS3VyWnauD25_E8psrcx7I=@protonmail.com>
<x1b18QXzxALwxxp8ehwcB7XORizrw5vOJ9BNXWpXbd2SJgUra-AFIyTgnM_yxKEtCg_frZcz916NLmm-pTsCD4Z7aOFprdQ_W87mHnn8vYg=@protonmail.com>
Feedback-ID: xmJdeebsJuWeTYpeWGhs6GJbYVTPvqSSDf5BTIISdYkvPlii55JSNfQlNKs6wbT1AOA1a_vQLvS0p4JWgkwDsA==:Ext:ProtonMail
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED,
DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM,
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
X-Mailman-Approved-At: Wed, 21 Aug 2019 17:05:30 +0000
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Storm: escrowed storage and messaging at L2/L3
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: Wed, 21 Aug 2019 17:04:46 -0000
Hi ZmnSCPxj,
> The Deaf Bob Attack
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> - If Alice does not publish the HTLC settlement transaction, then Bob w=
ill eventually enter the N2 state and get the stake+reward.
> - If Alice does publish the HTLC settlement transaction, without Bob gi=
ving the encrypted data, then Bob can just use the hashlock and reveal the =
decryption key.
> - The decryption key is useless without the encrypted data!
That is the main attack already addressed by couple of other guys in differ=
ent forms; and you have provided the most detailed explanation of it, thank=
you. I was working for its solution over the last day and I'd like to prop=
ose the following update: https://github.com/storm-org/storm-spec/issues/6#=
issuecomment-523497555
Briefly, I introduce two new intermediary HTLC transactions (called confirm=
ation and fallbacks). Alice has now a choice to sign HTLC fallback tx if sh=
e didn't get the data, and in that case she will get her money (reward) bac=
k and Bob's stake as a compensation. Bob can "appeal" to this by confirming=
that he had hold the data for Alice. Bob does this by providing a "preimag=
e" to the secret hashed by Alice.
This secret is composed at setup time by Alice, and she uses her newly-deri=
ved public key for both funding transaction output and deterministically de=
finition of some small portion of the source data. This portion is double-h=
ashed to 160-bit hash and included into HTLC fallback tx by Alice as a hash=
lock. Later, when Bob wants to prove that he still has the data available,=
he see the published HTLC transaction, extracts Alice public key and uses =
it to get the same deterministic piece of the source data as Alice. Bob com=
putes a single hash on the date, which gives him a preimage to unlock the h=
ash lock from HTLC transaction output before Alice will spend it (Alice's o=
utput is timelocked).
This solution requires Bob to select decription key at setup time, when he =
pre-signs the transaction, as you correctly have pointed out:
> If Bob already selected the decryption key at setup time, then Bob can ig=
nore Alice.
Now, we need to aviod situation where by selecting the encryption/decryptio=
n pair Bob knows which part of the data he needs to provide Alice in PCP pr=
oof, and can discard the rest of the data. This can be mitigated by requiri=
ng that the data have to be encrypted using EC multiplication with some fac=
tor provided by Alice at the request time.
The only case for possible cheating now is Alice not needing data anymore a=
nd avoiding paying the full amount for the storage. However, this can be a =
part of the Bob business risk and may be covered by some insurance + Alice'=
s reputation & taken into account by Bob at setup time.
Kind regards,
Maxim Orlovsky
|
