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
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
|
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 0EADEABC
for <bitcoin-dev@lists.linuxfoundation.org>;
Mon, 20 Nov 2017 19:59:05 +0000 (UTC)
X-Greylist: from auto-whitelisted by SQLgrey-1.7.6
Received: from sender-of-o51.zoho.com (sender-of-o51.zoho.com [135.84.80.216])
by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 33C098A
for <bitcoin-dev@lists.linuxfoundation.org>;
Mon, 20 Nov 2017 19:59:03 +0000 (UTC)
Received: from [10.8.0.102] (119246244201.ctinets.com [119.246.244.201]) by
mx.zohomail.com with SMTPS id 1511207941125564.2097344385272;
Mon, 20 Nov 2017 11:59:01 -0800 (PST)
From: Johnson Lau <jl2012@xbt.hk>
Message-Id: <24ADB268-7F46-4451-A53F-23D78CE66274@xbt.hk>
Content-Type: multipart/alternative;
boundary="Apple-Mail=_E9D453F8-CCA8-4B9E-8EAD-870D5636EE70"
Mime-Version: 1.0 (Mac OS X Mail 11.0 \(3445.1.6\))
Date: Tue, 21 Nov 2017 03:58:57 +0800
In-Reply-To: <CAAQs3wth=04PxDL6XzjTVYyZBiM1ZYHTK9-qRP8W+DAb53xMGg@mail.gmail.com>
To: Praveen Baratam <praveen.baratam@gmail.com>
References: <CAAQs3wuDPktHc6kiZXqTaatOheX4KP=TRgje0_-ED5h8iNs-MA@mail.gmail.com>
<F392E62C-00CF-4D91-BB6B-706F2A59C63B@xbt.hk>
<CAAQs3wth=04PxDL6XzjTVYyZBiM1ZYHTK9-qRP8W+DAb53xMGg@mail.gmail.com>
X-Mailer: Apple Mail (2.3445.1.6)
X-ZohoMailClient: External
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,HTML_MESSAGE,
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
Cc: bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Why SegWit Anyway?
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, 20 Nov 2017 19:59:05 -0000
--Apple-Mail=_E9D453F8-CCA8-4B9E-8EAD-870D5636EE70
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
charset=utf-8
Not really. BIP140 might be easier to implement, but in longterm the =
UTXO overhead is significant and unnecessary. There are also other =
benefits of segwit written in BIP141. Some of those are applicable even =
if you are making a new coin.
> On 21 Nov 2017, at 2:07 AM, Praveen Baratam =
<praveen.baratam@gmail.com> wrote:
>=20
> BIP 140 looks like it solves Tx Malleability with least impact on =
current practices. It is still a soft fork though.
>=20
> Finally, if we were to create an alternative cyptocurrency similar to =
Bitcoin, a Normalized Tx ID approach would be a better choice if I get =
it right!
> =E1=90=A7
>=20
> On Mon, Nov 20, 2017 at 11:15 PM, Johnson Lau <jl2012@xbt.hk =
<mailto:jl2012@xbt.hk>> wrote:
> We can=E2=80=99t =E2=80=9Cjust compute the Transaction ID the same way =
the hash for signing the transaction is computed=E2=80=9D because with =
different SIGHASH flags, there are 6 (actually 256) ways to hash a =
transaction.
>=20
> Also, changing the definition of TxID is a hardfork change, i.e. =
everyone are required to upgrade or a chain split will happen.
>=20
> It is possible to use =E2=80=9Cnormalised TxID=E2=80=9D (BIP140) to =
fix malleability issue. As a softfork, BIP140 doesn=E2=80=99t change the =
definition of TxID. Instead, the normalised txid (i.e. txid with =
scriptSig removed) is used when making signature. Comparing with segwit =
(BIP141), BIP140 does not have the side-effect of block size increase, =
and doesn=E2=80=99t provide any incentive to control the size of UTXO =
set. Also, BIP140 makes the UTXO set permanently bigger, as the database =
needs to store both txid and normalised txid
>=20
>> On 21 Nov 2017, at 1:24 AM, Praveen Baratam via bitcoin-dev =
<bitcoin-dev@lists.linuxfoundation.org =
<mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote:
>>=20
>> Bitcoin Noob here. Please forgive my ignorance.
>>=20
>> =46rom what I understand, in SegWit, the transaction needs to be =
serialized into a data structure that is different from the current one =
where signatures are separated from the rest of the transaction data.
>>=20
>> Why change the format at all? Why cant we just compute the =
Transaction ID the same way the hash for signing the transaction is =
computed?
>>=20
>> --=20
>> Dr. Praveen Baratam
>>=20
>> about.me =
<http://about.me/praveen.baratam>_________________________________________=
______
>> bitcoin-dev mailing list
>> bitcoin-dev@lists.linuxfoundation.org =
<mailto:bitcoin-dev@lists.linuxfoundation.org>
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev =
<https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev>
>=20
>=20
>=20
>=20
> --=20
> Dr. Praveen Baratam
>=20
> about.me <http://about.me/praveen.baratam>
--Apple-Mail=_E9D453F8-CCA8-4B9E-8EAD-870D5636EE70
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html;
charset=utf-8
<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;" class=3D""><div =
dir=3D"auto" style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
line-break: after-white-space;" class=3D"">Not really. BIP140 might be =
easier to implement, but in longterm the UTXO overhead is significant =
and unnecessary. There are also other benefits of segwit written in =
BIP141. Some of those are applicable even if you are making a new =
coin.<br class=3D""><div><br class=3D""><blockquote type=3D"cite" =
class=3D""><div class=3D"">On 21 Nov 2017, at 2:07 AM, Praveen Baratam =
<<a href=3D"mailto:praveen.baratam@gmail.com" =
class=3D"">praveen.baratam@gmail.com</a>> wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><div dir=3D"ltr" =
class=3D"">BIP 140 looks like it solves Tx Malleability with least =
impact on current practices. It is still a soft fork though.<div =
class=3D""><br class=3D""></div><div class=3D"">Finally, if we were to =
create an alternative cyptocurrency similar to Bitcoin, a Normalized Tx =
ID approach would be a better choice if I get it right!</div></div><div =
hspace=3D"streak-pt-mark" style=3D"max-height:1px" class=3D""><img =
alt=3D"" style=3D"width:0px;max-height:0px;overflow:hidden" =
src=3D"https://mailfoogae.appspot.com/t?sender=3DacHJhdmVlbi5iYXJhdGFtQGdt=
YWlsLmNvbQ%3D%3D&type=3Dzerocontent&guid=3D1dc0cb1a-dc60-4b69-828a=
-6db933a55c26" class=3D""><font color=3D"#ffffff" size=3D"1" =
class=3D"">=E1=90=A7</font></div><div class=3D"gmail_extra"><br =
class=3D""><div class=3D"gmail_quote">On Mon, Nov 20, 2017 at 11:15 PM, =
Johnson Lau <span dir=3D"ltr" class=3D""><<a =
href=3D"mailto:jl2012@xbt.hk" target=3D"_blank" =
class=3D"">jl2012@xbt.hk</a>></span> wrote:<br class=3D""><blockquote =
class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc =
solid;padding-left:1ex"><div =
style=3D"word-wrap:break-word;line-break:after-white-space" =
class=3D""><div class=3D"">We can=E2=80=99t =E2=80=9Cjust compute the =
Transaction ID the same way the hash for signing the transaction is =
computed=E2=80=9D because with different SIGHASH flags, there are 6 =
(actually 256) ways to hash a transaction.</div><div class=3D""><br =
class=3D""></div><div class=3D"">Also, changing the definition of TxID =
is a hardfork change, i.e. everyone are required to upgrade or a chain =
split will happen.</div><div class=3D""><br class=3D""></div>It is =
possible to use =E2=80=9Cnormalised TxID=E2=80=9D (BIP140) to fix =
malleability issue. As a softfork, BIP140 doesn=E2=80=99t change the =
definition of TxID. Instead, the normalised txid (i.e. txid with =
scriptSig removed) is used when making signature. Comparing with segwit =
(BIP141), BIP140 does not have the side-effect of block size increase, =
and doesn=E2=80=99t provide any incentive to control the size of UTXO =
set. Also, BIP140 makes the UTXO set permanently bigger, as the database =
needs to store both txid and normalised txid<br class=3D""><div =
class=3D""><div class=3D""><br class=3D""><blockquote type=3D"cite" =
class=3D""><div class=3D""><div class=3D"h5"><div class=3D"">On 21 Nov =
2017, at 1:24 AM, Praveen Baratam via bitcoin-dev <<a =
href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank" =
class=3D"">bitcoin-dev@lists.<wbr class=3D"">linuxfoundation.org</a>> =
wrote:</div><br =
class=3D"m_-4649666739189099192Apple-interchange-newline"></div></div><div=
class=3D""><div class=3D""><div class=3D"h5"><div dir=3D"ltr" =
class=3D""><div class=3D""><span =
style=3D"font-family:Verdana,arial,sans-serif;font-size:14px" =
class=3D"">Bitcoin Noob here. Please forgive my =
ignorance.</span></div><span =
style=3D"font-family:Verdana,arial,sans-serif;font-size:14px" =
class=3D""><div class=3D""><span =
style=3D"font-family:Verdana,arial,sans-serif;font-size:14px" =
class=3D""><br class=3D""></span></div>=46rom what I understand, in =
SegWit, the transaction needs to be serialized into a data structure =
that is different from the current one where signatures are separated =
from the rest of the transaction data.</span><div class=3D""><span =
style=3D"font-family:Verdana,arial,sans-serif;font-size:14px" =
class=3D""><br class=3D""></span></div><div class=3D""><span =
style=3D"font-family:Verdana,arial,sans-serif;font-size:14px" =
class=3D"">Why change the format at all? Why cant we just compute the =
Transaction ID the same way the hash for signing the transaction is =
computed?</span><br clear=3D"all" class=3D""><div class=3D""><br =
class=3D""></div>-- <br class=3D""><div =
class=3D"m_-4649666739189099192gmail_signature"><div =
style=3D"color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;b=
ackground-color:rgb(255,255,255)" class=3D"">Dr. Praveen =
Baratam</div><div =
style=3D"color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;b=
ackground-color:rgb(255,255,255)" class=3D""><br class=3D""></div><div =
style=3D"color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;b=
ackground-color:rgb(255,255,255)" class=3D""><a =
href=3D"http://about.me/praveen.baratam" style=3D"color:rgb(17,85,204)" =
target=3D"_blank" class=3D"">about.me</a></div></div>
</div></div></div></div>
______________________________<wbr class=3D"">_________________<span =
class=3D""><br class=3D"">bitcoin-dev mailing list<br class=3D""><a =
href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank" =
class=3D"">bitcoin-dev@lists.<wbr class=3D"">linuxfoundation.org</a><br =
class=3D""><a =
href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
target=3D"_blank" class=3D"">https://lists.linuxfoundation.<wbr =
class=3D"">org/mailman/listinfo/bitcoin-<wbr class=3D"">dev</a><br =
class=3D""></span></div></blockquote></div><br =
class=3D""></div></div></blockquote></div><br class=3D""><br clear=3D"all"=
class=3D""><div class=3D""><br class=3D""></div>-- <br class=3D""><div =
class=3D"gmail_signature" data-smartmail=3D"gmail_signature"><div =
style=3D"color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;b=
ackground-color:rgb(255,255,255)" class=3D"">Dr. Praveen =
Baratam</div><div =
style=3D"color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;b=
ackground-color:rgb(255,255,255)" class=3D""><br class=3D""></div><div =
style=3D"color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;b=
ackground-color:rgb(255,255,255)" class=3D""><a =
href=3D"http://about.me/praveen.baratam" style=3D"color:rgb(17,85,204)" =
target=3D"_blank" class=3D"">about.me</a></div></div>
</div>
</div></blockquote></div><br class=3D""></div></body></html>=
--Apple-Mail=_E9D453F8-CCA8-4B9E-8EAD-870D5636EE70--
|
