summaryrefslogtreecommitdiff
path: root/3c/035e29dbda2727ff5fe9113ae421d7591112de
blob: c94f6513c5de19e7b379d28069987a603617f35b (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
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 0A5AE2640
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Mon, 11 Feb 2019 04:29:52 +0000 (UTC)
X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6
Received: from mail-40130.protonmail.ch (mail-40130.protonmail.ch
	[185.70.40.130])
	by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 2622125A
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Mon, 11 Feb 2019 04:29:51 +0000 (UTC)
Date: Mon, 11 Feb 2019 04:29:42 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
	s=default; t=1549859389;
	bh=dA1vkhY6Ho/stxjFaucq4QycKLAYQEif5/TSgzTw2cE=;
	h=Date:To:From:Reply-To:Subject:In-Reply-To:References:Feedback-ID:
	From;
	b=o2lomqoJXN/KlhZcRfbMZqQXENZsLgZKeQv6BFTurU27Ce69Wou29y/dazPGlehZL
	DQj3HS1zC557eQFbcgkRkkBDmiiSB2a6UfEDWNsfeJW2K0Zx3r/uHCZOXc4AO1g74P
	RD11HAnvP8gf11VOREfrKkJRNfsh0Ba4KRuL0Fl4=
To: "Kenshiro \\[\\]" <tensiam@hotmail.com>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Reply-To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Message-ID: <U-ugv1xWdp4czsN38WhD6KQUPcYa4VLxNzUusM3YLRu4825eigldn3xTOw6IyoqpyFbymdKxWUGOQdlknr3L7rBOtssEKeYMkW4RKj5Rc1o=@protonmail.com>
In-Reply-To: <DB6PR10MB183228F27750132F9A6A3542A6690@DB6PR10MB1832.EURPRD10.PROD.OUTLOOK.COM>
References: <DB6PR10MB183228F27750132F9A6A3542A6690@DB6PR10MB1832.EURPRD10.PROD.OUTLOOK.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
X-Mailman-Approved-At: Tue, 12 Feb 2019 12:46:40 +0000
Subject: Re: [bitcoin-dev] Implementing Confidential Transactions in
	extension blocks
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, 11 Feb 2019 04:29:53 -0000

Good morning Kenshiro,

> - Soft fork: old nodes see CT transactions as "sendtoany" transactions

There is a position that fullnodes must be able to get a view of the UTXO s=
et, and extension blocks (which are invisible to pre-extension-block fullno=
des) means that fullnodes no longer have an accurate view of the UTXO set.
SegWit still provides pre-SegWit fullnodes with a view of the UTXO set, alt=
hough pre-SegWit fullnodes could be convinced that a particular UTXO is any=
one-can-spend even though they are no longer anyone-can-spend.

Under this point-of-view, then, extension block is "not" soft fork.
It is "evil" soft fork since older nodes are forced to upgrade as their int=
ended functionality becomes impossible.
In this point-of-view, it is no better than a hard fork, which at least is =
very noisy about how older fullnode versions will simply stop working.

> - Safe: if there is a software bug in CT it's impossible to create new co=
ins because the coins move from normal block to normal block as public tran=
sactions

I think more relevant here is the issue of a future quantum computing breac=
h of the algorithms used to implement confidentiality.

I believe this is also achievable with a non-extension-block approach by im=
plementing a globally-verified publicly-visible counter of the total amount=
 in all confidential transaction outputs.
Then it becomes impossible to move from confidential to public transactions=
 with a value more than this counter, thus preventing inflation even if a f=
uture QC breach allows confidential transaction value commitments to be ope=
ned to any value.

(do note that a non-extension-block approach is a definite hardfork)

> - Capacity increase: the CT signature is stored in the extension block, s=
o CT transactions increase the maximum number of transactions per block

This is not an unalloyed positive: block size increase, even via extension =
block, translates to greater network capacity usage globally on all fullnod=
es.

Regards,
ZmnSCPxj