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
|
Return-Path: <jl2012@xbt.hk>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
[172.17.192.35])
by mail.linuxfoundation.org (Postfix) with ESMTPS id DC84E41C
for <bitcoin-dev@lists.linuxfoundation.org>;
Sun, 9 Dec 2018 19:13:43 +0000 (UTC)
X-Greylist: from auto-whitelisted by SQLgrey-1.7.6
Received: from sender-of-o53.zoho.com (sender-of-o53.zoho.com [135.84.80.218])
by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 559AF14D
for <bitcoin-dev@lists.linuxfoundation.org>;
Sun, 9 Dec 2018 19:13:43 +0000 (UTC)
ARC-Seal: i=1; a=rsa-sha256; t=1544382819; cv=none; d=zoho.com; s=zohoarc;
b=HmnUA+yXdbtHYyD0eTCD9FET/SzyQUsIT+PEkzZHxFyLsUxVTBQzRGZ0dMzOQ6Wbl0GBT+IyTXxfGd9h/d5ZzybtSfApJ+NKnV0V/UiNBOI6Wo6DTh0WNg2iS87n15myWMlVPqR0jOgJgmKdWenCZjBg42qxNk6cHaT1qmXnxn8=
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com;
s=zohoarc; t=1544382819;
h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:To:ARC-Authentication-Results;
bh=zjhbfm51yiRkxxC8yBws0iNqUZTN/JRwrjOTycYyNRY=;
b=T0mGAZeDzhzI99vGkn62Qa0l78C6ZByn1gvWDdTMhym5e5LJbmWkmaY2BFg1xvrfGXbFqbA9PFhSczIWKwGMpE0rfOKkTCaUxhzUU9p5yt9OYsBtB9BibzYJ8Z/JtF6mdqv20i6e6HaCky1OAkEgw57MsqB6ZNNXPIy1aGd8SN0=
ARC-Authentication-Results: i=1; mx.zoho.com; dkim=pass header.i=xbt.hk;
spf=pass smtp.mailfrom=jl2012@xbt.hk;
dmarc=pass header.from=<jl2012@xbt.hk> header.from=<jl2012@xbt.hk>
Received: from [10.8.0.105] (n218103234118.netvigator.com [218.103.234.118])
by mx.zohomail.com with SMTPS id 1544382818681791.0238836434062;
Sun, 9 Dec 2018 11:13:38 -0800 (PST)
Content-Type: text/plain;
charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 12.0 \(3445.100.39\))
From: Johnson Lau <jl2012@xbt.hk>
In-Reply-To: <CAMZUoKkJdU0P_dVRvHn5zY6xUHYUptdK221ioQMp3FXZAerp3Q@mail.gmail.com>
Date: Mon, 10 Dec 2018 03:13:34 +0800
Content-Transfer-Encoding: quoted-printable
Message-Id: <702FE74C-119C-4D14-BCD3-85C4355356A2@xbt.hk>
References: <CAPg+sBhuPG-2GXc+Bp0yv5ywry2fk56LPLT4AY0Kcs+YEoz4FA@mail.gmail.com>
<CAPg+sBiu0BjZEtz-t7m3M+TnAEDG_k1GKtxwkOKh6qrSezUO7g@mail.gmail.com>
<CAMZUoKkJdU0P_dVRvHn5zY6xUHYUptdK221ioQMp3FXZAerp3Q@mail.gmail.com>
To: Russell O'Connor <roconnor@blockstream.io>,
bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
X-Mailer: Apple Mail (2.3445.100.39)
X-ZohoMailClient: External
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE
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: Mon, 10 Dec 2018 17:29:40 +0000
Subject: Re: [bitcoin-dev] Safer sighashes and more granular SIGHASH_NOINPUT
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: Sun, 09 Dec 2018 19:13:44 -0000
The current proposal is that a 64-byte signature will be used for the =
default =E2=80=9Csigning all=E2=80=9D sighash, and 65-byte for other =
sighash types. The space saved will allow a few more txs in a block, so =
I think it worths doing. However, this also makes witness weight =
estimation more difficult in multisig cases.
This idea of signing witness weight has been brought up before. I think =
the concern is the difficulty to estimate the witness weight for complex =
scripts, which need this feature most. So it will work when it is not =
needed, and will not work when it is needed.
Is there any script example that witness size malleability is =
unavoidable?
> On 7 Dec 2018, at 12:57 AM, Russell O'Connor via bitcoin-dev =
<bitcoin-dev@lists.linuxfoundation.org> wrote:
>=20
> One more item to consider is "signature covers witness weight".
>=20
> While signing the witness weight doesn't completely eliminate witness =
malleability (of the kind that can cause grief for compact blocks), it =
does eliminate the worst kind of witness malleability from the user's =
perspective, the kind where malicious relay nodes increase the amount of =
witness data and therefore reduce the overall fee-rate of the =
transaction. Generally users should strive to construct their Bitcoin =
Scripts in such a way that witness malleability isn't possible, but as =
you are probably aware, this can be quite difficult to achieve as =
Scripts become more complex and maybe isn't even possible for some =
complex Scripts.
>=20
> Given the new fixed-sized signature of the Schnorr BIP, it becomes =
much easier to compute the final witness weight prior to signing. In =
complex multi-party signing protocol, the final witness weight might not =
be known at signing time for everyone involved, so the "signature covers =
witness weight" ought to be optional.
>=20
>=20
|
