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
111
112
113
114
115
116
|
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 9EB75C6E
for <bitcoin-dev@lists.linuxfoundation.org>;
Fri, 8 Nov 2019 05:12:03 +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 E4E5067F
for <bitcoin-dev@lists.linuxfoundation.org>;
Fri, 8 Nov 2019 05:12:02 +0000 (UTC)
Date: Fri, 08 Nov 2019 05:11:53 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com;
s=default; t=1573189920;
bh=YJcMT+vmeq9yFxX1/JiyJuuDTRis6aSsnbxfFpflLcY=;
h=Date:To:From:Reply-To:Subject:In-Reply-To:References:Feedback-ID:
From;
b=cZLyHth5LRt/Km0ZFt+0Wp9lqulkQ+cuCbPvuFNSskze0fGEi8ekeyskS6cz/lAS+
09995GTAldYz5VbeqxHvLccc5gBdJU4Bgt6cy/QzjHosHB8vd2R8sOyPFBzD5Mv86C
CSKAZHaTimExr/bUnjnGbc5K0HcHLv3RW4+d3dVk=
To: Pieter Wuille <pieter.wuille@gmail.com>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Reply-To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Message-ID: <sZtrFEIbPoH5v6IpNboec9kgSui-E8QLHllL3u3TgB42iRU3zkzi6cJuGTqUp1-9MMp0kURGuMRCmBv9AC6e9RPmMZpGVSAr0-HSRfyfhzM=@protonmail.com>
In-Reply-To: <CAPg+sBjC-D2iWYywj_X-evQoWx56nb0YnASLVwCSCzWT6Guu3A@mail.gmail.com>
References: <CAPg+sBjC-D2iWYywj_X-evQoWx56nb0YnASLVwCSCzWT6Guu3A@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=-0.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,
DKIM_VALID, DKIM_VALID_AU, DOS_RCVD_IP_TWICE_B, FREEMAIL_FROM,
FROM_LOCAL_NOVOWEL,
RCVD_IN_DNSWL_LOW autolearn=no version=3.3.1
X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on
smtp1.linux-foundation.org
Subject: Re: [bitcoin-dev] Bech32 weakness and impact on bip-taproot
addresses
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, 08 Nov 2019 05:12:03 -0000
Good morning Pieter, and all,
Can we modify Bech32 SegWit address format for version 1 and above as below=
?
* The data-part values:
** 1 byte: the witness version
+ ** If the witness version is non-zero, 1 byte: the length of the witn=
ess program.
** A conversion of the 2-to-40-byte witness program (as defined by [h=
ttps://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki BIP141]) to b=
ase32:
*** Start with the bits of the witness program, most significant bit =
per byte first.
*** Re-arrange those bits into groups of 5, and pad with zeroes at th=
e end if needed.
*** Translate those bits to characters using the table above.
This retains the ability of a bech32 address to specify any valid witness l=
ength and allows future version 1 addresses with lengths other than 32, whi=
le closing this malleation.
Older software being given the modified v1 address format would mis-send it=
to the wrong witness program, however.
Alternately we could just keep using version 0 in the address format foreve=
r.
The requirement would be to ensure that SegWit vN (N >=3D 1) output witness=
programs would have a data-part value encoded as below:
* The data-part values:
** 1 byte: legacy witness version, which must always be 0.
** 1 byte: actual witness version, which must be non-zero.
** 1 byte: padding length: 0 or 1.
** If padding length is 1, 1 byte: padding, which must be 0.
** 1 byte: witness program length.
** variable: witness program.
A writer for a v1 or later address would initially set an empty padding, th=
en compute:
1 // actual witness version
+ 1 // padding length
+ 1 // witness length
+ witness_length
If the above sum is 20 or 32, then the writer selects a non-zero padding an=
d inserts the padding byte so that the above sum is now 21 or 33.
To a reader that understands only bech32 v0, such an encoding would look li=
ke a SegWit v0 invalid-program-length, and be rejected.
A reader which understands the above protocol would, instead of rejecting a=
SegWit v0 invalid-program-length, instead attempt to parse it as above fir=
st, and consider it as SegWit v1 or higher if it was parsed correctly as ab=
ove.
The above proposal is of course ridiculous and I am now currently running d=
iagnostics on my processing units to see if further glitches occur in test =
reasoning skills.
Regards,
ZmnSCPxj
|
