summaryrefslogtreecommitdiff
path: root/0b/c7d1d037f26c0891cf8d6c49717bb5fa86c02a
blob: ca085eb298223bd8722327418085862303e961c8 (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
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
237
238
239
240
241
242
243
244
245
246
247
248
Return-Path: <mark@friedenbach.org>
Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org
	[172.17.192.35])
	by mail.linuxfoundation.org (Postfix) with ESMTPS id 1614AF74
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Thu, 27 Aug 2015 23:33:16 +0000 (UTC)
X-Greylist: whitelisted by SQLgrey-1.7.6
Received: from mail-io0-f181.google.com (mail-io0-f181.google.com
	[209.85.223.181])
	by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3E31213C
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Thu, 27 Aug 2015 23:33:15 +0000 (UTC)
Received: by iodt126 with SMTP id t126so75645485iod.2
	for <bitcoin-dev@lists.linuxfoundation.org>;
	Thu, 27 Aug 2015 16:33:14 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
	d=1e100.net; s=20130820;
	h=x-gm-message-state:mime-version:in-reply-to:references:from:date
	:message-id:subject:cc:content-type;
	bh=b7FJE4hxIUVTXkLl/Z9ANUs6/4xq4uKWOmRNe6jMsnc=;
	b=ZnQC0ixhvwKp5jCpHL6bV4z7h/irQjsbedl4slZEKXZ9+ZZGjbD4El7WTCS+6AwavW
	zruqQ9B7jKrqHuow+bGIeF+G93x/NDCKkNq3FcxSnfkoAA3Qlxg9gdGLuFGV9pg9KgyQ
	vMEmKuzzuQ1f9Q3ZTpI6DmxkIeV0cDMBJTz3CbKk/GnIipzQFk2bTVOQ0C3PmkO9SqzL
	1FFNWrzuanxOhuS7mac/lb/cbe5L5R/DheGzxujUWmo2PmnI46Nj1ce83oskhCGPLvLk
	zzeBB7KxCKi2PXWnlrvQldBRVe0RBatrtTvnsTw5oiTrFsCTM8VMB6/SylbalDK27eZP
	yKuQ==
X-Gm-Message-State: ALoCoQn9bB90Fe2JwWF1A5ydyh9NMeAm+R2tvcxtZJgy85E50UFp1f6zmy9BbcABBEtZIVcYKJLJ
X-Received: by 10.107.11.67 with SMTP id v64mr13470761ioi.105.1440718394634;
	Thu, 27 Aug 2015 16:33:14 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.107.135.104 with HTTP; Thu, 27 Aug 2015 16:32:55 -0700 (PDT)
X-Originating-IP: [24.4.96.213]
In-Reply-To: <CAOG=w-to4Vrx4ykKJTy5EAyN4GZd6Q=G5FzqZH-5J3Thz_VNpQ@mail.gmail.com>
References: <CADJgMztgE_GkbrsP7zCEHNPA3P6T=aSFfhkcN-q=gVhWP0vKXg@mail.gmail.com>
	<CADJgMzv8G3EqLBwEYRHJZ+fO_Jwzy0koi2pJ_iNRkXmoVarGcg@mail.gmail.com>
	<CABm2gDod9z6ksgaCv86qFCyKLTQSL3+oNns+__5H77hVhs05DQ@mail.gmail.com>
	<CAOG=w-sbOcaogkic2i4A5eZnBQ79LUibsGy0dyKyvQg53ktY1Q@mail.gmail.com>
	<55DA6470.9040301@thinlink.com>
	<CAAS2fgQKQpHu-nC1uSrigDx2JLUt64p-LqidVmiuULDE0MJCFQ@mail.gmail.com>
	<CABm2gDqW7OGuyZ1BTTeeivDf9wFVsAK9AaGYm8XWwLb2O2Lb+g@mail.gmail.com>
	<CAOG=w-ubk3nPfxy25Hd6kPeehf7vnYD5chksLWU5wU2t=jL5TA@mail.gmail.com>
	<CAOG=w-to4Vrx4ykKJTy5EAyN4GZd6Q=G5FzqZH-5J3Thz_VNpQ@mail.gmail.com>
From: Mark Friedenbach <mark@friedenbach.org>
Date: Thu, 27 Aug 2015 16:32:55 -0700
Message-ID: <CAOG=w-tuFtX2t+0FVfkoObw_a9-7j4LwX87YJU1n7adYu=DMdQ@mail.gmail.com>
Cc: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary=001a113f9694224806051e536422
X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00,HTML_MESSAGE,
	MISSING_HEADERS,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] [BIP-draft] CHECKSEQUENCEVERIFY - An opcode for
 relative locktime
X-BeenThere: bitcoin-dev@lists.linuxfoundation.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Bitcoin Development 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: Thu, 27 Aug 2015 23:33:16 -0000

--001a113f9694224806051e536422
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

So I've created 2 new repositories with changed rules regarding
sequencenumbers:

https://github.com/maaku/bitcoin/tree/sequencenumbers2

This repository inverts (un-inverts?) the sequence number. nSequence=3D1
means 1 block relative lock-height. nSequence=3DLOCKTIME_THRESHOLD means 1
second relative lock-height. nSequence>=3D0x80000000 (most significant bit
set) is not interpreted as a relative lock-time.

https://github.com/maaku/bitcoin/tree/sequencenumbers3

This repository not only inverts the sequence number, but also interprets
it as a fixed-point number. This allows up to 5 year relative lock times
using blocks as units, and saves 12 low-order bits for future use. Or, up
to about 2 year relative lock times using seconds as units, and saves 4
bits for future use without second-level granularity. More bits could be
recovered from time-based locktimes by choosing a higher granularity (a
soft-fork change if done correctly).

On Tue, Aug 25, 2015 at 3:08 PM, Mark Friedenbach <mark@friedenbach.org>
wrote:

> To follow up on this, let's say that you want to be able to have up to 1
> year relative lock-times. This choice is somewhat arbitrary and what I
> would like some input on, but I'll come back to this point.
>
>  * 1 bit is necessary to enable/disable relative lock-time.
>
>  * 1 bit is necessary to indicate whether seconds vs blocks as the unit o=
f
> measurement.
>
>  * 1 year of time with 1-second granularity requires 25 bits. However
> since blocks occur at approximately 10 minute intervals on average, havin=
g
> a relative lock-time significantly less than this interval doesn't make
> much sense. A granularity of 256 seconds would be greater than the Nyquis=
t
> frequency and requires only 17 bits.
>
>  * 1 year of blocks with 1-block granularity requires 16 bits.
>
> So time-based relative lock time requires about 19 bits, and block-based
> relative lock-time requires about 18 bits. That leaves 13 or 14 bits for
> other uses.
>
> Assuming a maximum of 1-year relative lock-times. But what is an
> appropriate maximum to choose? The use cases I have considered have only
> had lock times on the order of a few days to a month or so. However I wou=
ld
> feel uncomfortable going less than a year for a hard maximum, and am havi=
ng
> trouble thinking of any use case that would require more than a year of
> lock-time. Can anyone else think of a use case that requires >1yr relativ=
e
> lock-time?
>
> TL;DR
>
> On Sun, Aug 23, 2015 at 7:37 PM, Mark Friedenbach <mark@friedenbach.org>
> wrote:
>
>> A power of 2 would be far more efficient here. The key question is how
>> long of a relative block time do you need? Figure out what the maximum
>> should be ( I don't know what that would be, any ideas?) and then see ho=
w
>> many bits you have left over.
>> On Aug 23, 2015 7:23 PM, "Jorge Tim=C3=B3n" <
>> bitcoin-dev@lists.linuxfoundation.org> wrote:
>>
>>> On Mon, Aug 24, 2015 at 3:01 AM, Gregory Maxwell via bitcoin-dev
>>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>>> > Seperately, to Mark and Btcdrank: Adding an extra wrinkel to the
>>> > discussion has any thought been given to represent one block with mor=
e
>>> > than one increment?  This would leave additional space for future
>>> > signaling, or allow, for example, higher resolution numbers for a
>>> > sharechain commitement.
>>>
>>> No, I don't think anybody thought about this. I just explained this to
>>> Pieter using "for example, 10 instead of 1".
>>> He suggested 600 increments so that it is more similar to timestamps.
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev@lists.linuxfoundation.org
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>
>>
>

--001a113f9694224806051e536422
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div><div>So I&#39;ve created 2 new repositories with chan=
ged rules regarding sequencenumbers:<br><br><a href=3D"https://github.com/m=
aaku/bitcoin/tree/sequencenumbers2">https://github.com/maaku/bitcoin/tree/s=
equencenumbers2</a><br><br></div>This repository inverts (un-inverts?) the =
sequence number. nSequence=3D1 means 1 block relative lock-height. nSequenc=
e=3DLOCKTIME_THRESHOLD means 1 second relative lock-height. nSequence&gt;=
=3D0x80000000 (most significant bit set) is not interpreted as a relative l=
ock-time.<br><br><a href=3D"https://github.com/maaku/bitcoin/tree/sequencen=
umbers3">https://github.com/maaku/bitcoin/tree/sequencenumbers3</a><br><br>=
</div>This repository not only inverts the sequence number, but also interp=
rets it as a fixed-point number. This allows up to 5 year relative lock tim=
es using blocks as units, and saves 12 low-order bits for future use. Or, u=
p to about 2 year relative lock times using seconds as units, and saves 4 b=
its for future use without second-level granularity. More bits could be rec=
overed from time-based locktimes by choosing a higher granularity (a soft-f=
ork change if done correctly).<br></div><div class=3D"gmail_extra"><br><div=
 class=3D"gmail_quote">On Tue, Aug 25, 2015 at 3:08 PM, Mark Friedenbach <s=
pan dir=3D"ltr">&lt;<a href=3D"mailto:mark@friedenbach.org" target=3D"_blan=
k">mark@friedenbach.org</a>&gt;</span> wrote:<br><blockquote class=3D"gmail=
_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:=
1ex"><div dir=3D"ltr"><div><div>To follow up on this, let&#39;s say that yo=
u want to be able to have up to 1 year relative lock-times. This choice is =
somewhat arbitrary and what I would like some input on, but I&#39;ll come b=
ack to this point.<br><br></div><div>=C2=A0* 1 bit is necessary to enable/d=
isable relative lock-time.<br></div><div><br></div><div>=C2=A0* 1 bit is ne=
cessary to indicate whether seconds vs blocks as the unit of measurement.<b=
r><br></div><div>=C2=A0* 1 year of time with 1-second granularity requires =
25 bits. However since blocks occur at approximately 10 minute intervals on=
 average, having a relative lock-time significantly less than this interval=
 doesn&#39;t make much sense. A granularity of 256 seconds would be greater=
 than the Nyquist frequency and requires only 17 bits.<br><br></div><div>=
=C2=A0* 1 year of blocks with 1-block granularity requires 16 bits.<br></di=
v><div><br></div>So time-based relative lock time requires about 19 bits, a=
nd block-based relative lock-time requires about 18 bits. That leaves 13 or=
 14 bits for other uses.<br><br></div><div>Assuming a maximum of 1-year rel=
ative lock-times. But what is an appropriate maximum to choose? The use cas=
es I have considered have only had lock times on the order of a few days to=
 a month or so. However I would feel uncomfortable going less than a year f=
or a hard maximum, and am having trouble thinking of any use case that woul=
d require more than a year of lock-time. Can anyone else think of a use cas=
e that requires &gt;1yr relative lock-time?<br></div><div><br></div>TL;DR <=
br></div><div class=3D"HOEnZb"><div class=3D"h5"><div class=3D"gmail_extra"=
><br><div class=3D"gmail_quote">On Sun, Aug 23, 2015 at 7:37 PM, Mark Fried=
enbach <span dir=3D"ltr">&lt;<a href=3D"mailto:mark@friedenbach.org" target=
=3D"_blank">mark@friedenbach.org</a>&gt;</span> wrote:<br><blockquote class=
=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padd=
ing-left:1ex"><p dir=3D"ltr">A power of 2 would be far more efficient here.=
 The key question is how long of a relative block time do you need? Figure =
out what the maximum should be ( I don&#39;t know what that would be, any i=
deas?) and then see how many bits you have left over.</p><div><div>
<div class=3D"gmail_quote">On Aug 23, 2015 7:23 PM, &quot;Jorge Tim=C3=B3n&=
quot; &lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=
=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:<br type=3D=
"attribution"><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;=
border-left:1px #ccc solid;padding-left:1ex">On Mon, Aug 24, 2015 at 3:01 A=
M, Gregory Maxwell via bitcoin-dev<br>
&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_bla=
nk">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:<br>
&gt; Seperately, to Mark and Btcdrank: Adding an extra wrinkel to the<br>
&gt; discussion has any thought been given to represent one block with more=
<br>
&gt; than one increment?=C2=A0 This would leave additional space for future=
<br>
&gt; signaling, or allow, for example, higher resolution numbers for a<br>
&gt; sharechain commitement.<br>
<br>
No, I don&#39;t think anybody thought about this. I just explained this to<=
br>
Pieter using &quot;for example, 10 instead of 1&quot;.<br>
He suggested 600 increments so that it is more similar to timestamps.<br>
_______________________________________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">=
bitcoin-dev@lists.linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.org/mail=
man/listinfo/bitcoin-dev</a><br>
</blockquote></div>
</div></div></blockquote></div><br></div>
</div></div></blockquote></div><br></div>

--001a113f9694224806051e536422--