summaryrefslogtreecommitdiff
path: root/a4/9e1cd7e3bd4324b9a1e4dd5c27c75900bdc623
blob: 90d20343a4b7dd4dd891b7b9695778722e3afa9f (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
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 0E96223E0
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Fri,  6 Sep 2019 14:32:50 +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 03A5A89C
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Fri,  6 Sep 2019 14:32:47 +0000 (UTC)
Date: Fri, 06 Sep 2019 14:32:38 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
	s=default; t=1567780365;
	bh=zCpvj+1j0+y110OUR9o5CZiaSTg42a5lnpGEHR0c5n0=;
	h=Date:To:From:Cc:Reply-To:Subject:In-Reply-To:References:
	Feedback-ID:From;
	b=I8iVICoIgG3bEDyUw7acqfKrw+f3RnS6Y1g+XAFjZB6AWc9hkVafybjbJwvRXwHsO
	5Hx61u5Zft0U9dXy+iS7PSascku5znhTzwBbEe6nAvAv8nFHZ7y6Gr47fBeucQWeTK
	oLqmIP59cvAST2N0GrHc+gWKsKA6HK6T3Pbiq2AU=
To: Christian Decker <decker.christian@gmail.com>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Reply-To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Message-ID: <G_LSM42y_gQFNVrTfHHN5hqR_foZU6AlOJkfz9zMDLFyQGdk4opZ14QC97w2rjrw4UmWTwEkJDKEc_eUMItdmxEsQOl7S-gBO2y8ovFPBc0=@protonmail.com>
In-Reply-To: <87mufhva0k.fsf@gmail.com>
References: <87mufhva0k.fsf@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
Cc: "lightning-dev@lists.linuxfoundation.org"
	<lightning-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Reconciling the off-chain and on-chain models
	with eltoo
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: Fri, 06 Sep 2019 14:32:50 -0000

Good morning Christian,

This is effectively transaction cut-through.
I mention this in passing here: https://lists.linuxfoundation.org/pipermail=
/lightning-dev/2019-April/001986.html

> I observe that one may consider any offchain system a specialization of a=
n offchain transaction cut-through system.
> Thus, one may model changes to the offchain system state as the creation =
of some transactions, followed by a cut-through of those transactions into =
the new state.

Basically, we can send a transaction that spends a subset of the current st=
ate txos to the participants in the update mechanism.
Then the participants can agree that it is a valid spend of the specified s=
tate txos, and agree to sign a new state with the spent txos deleted and th=
e new txos of the transaction inserted.
Disagreement at this point is essentially a "if your tx is so valid why do =
you not try it on the base blockchain layer huh?" challenge and is basicall=
y an invitation to close it unilaterally and enforce the contract on the bl=
ockchain.

The "difficulty" in Poon-Dryja is not very onerous in my opinion; see the s=
ketch here: https://lists.linuxfoundation.org/pipermail/lightning-dev/2018-=
August/001383.html

Of note is that any contract with a relative locktime requirement would not=
 make sense to maintain offchain.
If one wishes to select a relative locktime relative to the current moment,=
 one can quite easily compute an absolute timelock.

Another note, is that contracts with timelocks need to be enforced onchain =
on or before the timelock.
Under Decker-Russell-Osuntokun the onchain enforcement needs to be triggere=
d early according to the CSV security parameter; this is not an issue under=
 Poon-Dryja (as the CSV is in a later transaction).
Under Decker-Russell-Osuntokun due to the use of `SIGHASH_NOINPUT` and the =
non-stable txids involved, any transaction you wish to transport in the off=
chain update mechanism needs to also be signed under `SIGHASH_NOINPUT`, but=
 again this is not onerous.
In any case it is "only" a matter of tradeoffs one is willing to work under=
 anyway, and Decker-Russell-Osuntokun is very cool and uses `nLockTime` and=
 `OP_CHECKLOCKTIMEVERIFY` in a very clever way.

Regards,
ZmnSCPxj