Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 62AA8E55 for ; Thu, 17 Sep 2015 04:24:02 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-io0-f172.google.com (mail-io0-f172.google.com [209.85.223.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 51E5E12E for ; Thu, 17 Sep 2015 04:24:01 +0000 (UTC) Received: by iofb144 with SMTP id b144so9748716iof.1 for ; Wed, 16 Sep 2015 21:24:00 -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:to:cc:content-type; bh=02fxMbKqtlfzFfjIGT4ACKpRNkiZBcnoKMx27/QsZyA=; b=Zj17AbHrw02ccu9jq7T85tzGIIXHuzH0c3BoaBPNkaZ9QwD6uTeUcyOxPUV1AsdE5e lZDK734Jxbe3Hyn/ogYsdZibYlt/SE5NSLlV+kXSwm8jycYb/0bBiY/ZW4bPykcD+xz3 JFqU595/OV9+5PzmdqON/G4eFGCVIUfdPspuUd3YPfdylUDRPIsP3j6pufknPo6RQHTd gOiurS2KPibbzYbGJ/uhjm9hEZZUwRZLp0KH9Gvm+Wy1eJT3jlGRrG4r8IaVicRyQCGQ 11cs4wdxove+UFdfmbmWhmrSnS3QtWtYKIz8Me1RMOVZH28bwN9zVLSzPsVyhkdW9tf3 O+qA== X-Gm-Message-State: ALoCoQmOdftNL9LR7NIs/JGeShE+n7G61ZzxT8dSBk3P7wus6CUbZ8zWXTsl2xaJPTBUfvVOmJjy X-Received: by 10.107.11.154 with SMTP id 26mr2690367iol.105.1442463840762; Wed, 16 Sep 2015 21:24:00 -0700 (PDT) MIME-Version: 1.0 Received: by 10.107.135.104 with HTTP; Wed, 16 Sep 2015 21:23:41 -0700 (PDT) X-Originating-IP: [66.130.36.70] In-Reply-To: <4E3B7469-1018-4649-8DF1-6597F82774F1@gmail.com> References: <55DA6470.9040301@thinlink.com> <4E3B7469-1018-4649-8DF1-6597F82774F1@gmail.com> From: Mark Friedenbach Date: Thu, 17 Sep 2015 00:23:41 -0400 Message-ID: To: Eric Lombrozo Content-Type: multipart/alternative; boundary=001a113f7e7cd4a547051fe9c866 X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,HTML_MESSAGE, 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 Cc: Btc Drak via bitcoin-dev 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 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 17 Sep 2015 04:24:02 -0000 --001a113f7e7cd4a547051fe9c866 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Eric, that would be, I think, my sequencenumbers2 branch in which nSequence is an explicit relative lock-time field (unless the most significant bit is set). That has absolutely clear semantics. You should comment on #6312 where this is being discussed. On Wed, Sep 16, 2015 at 7:23 PM, Eric Lombrozo wrote: > I'd rather replace the whole nSequence thing with an explicit relative > locktime with clear semantics...but I'm not going to fight this one too > much. > > > On September 16, 2015 6:40:06 PM EDT, Btc Drak via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: >> >> Where do we stand now on which sequencenumbers variation to use? We >> really should make a decision now. >> >> On Fri, Aug 28, 2015 at 12:32 AM, Mark Friedenbach via bitcoin-dev < >> bitcoin-dev@lists.linuxfoundation.org> wrote: >> >>> 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=3D= 1 >>> means 1 block relative lock-height. nSequence=3DLOCKTIME_THRESHOLD mean= s 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 relativ= e >>> lock times using blocks as units, and saves 12 low-order bits for futur= e >>> 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 >>> 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 uni= t >>>> of measurement. >>>> >>>> * 1 year of time with 1-second granularity requires 25 bits. However >>>> since blocks occur at approximately 10 minute intervals on average, ha= ving >>>> a relative lock-time significantly less than this interval doesn't mak= e >>>> much sense. A granularity of 256 seconds would be greater than the Nyq= uist >>>> 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 on= ly >>>> 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 for a hard maximum, and am h= aving >>>> trouble thinking of any use case that would require more than a year o= f >>>> lock-time. Can anyone else think of a use case that requires >1yr rela= tive >>>> lock-time? >>>> >>>> TL;DR >>>> >>>> On Sun, Aug 23, 2015 at 7:37 PM, Mark Friedenbach >>> > wrote: >>>> >>>>> A power of 2 would be far more efficient here. The key question is ho= w >>>>> long of a relative block time do you need? Figure out what the maximu= m >>>>> should be ( I don't know what that would be, any ideas?) and then see= how >>>>> 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 >>>>>> wrote: >>>>>> > Seperately, to Mark and Btcdrank: Adding an extra wrinkel to the >>>>>> > discussion has any thought been given to represent one block with >>>>>> more >>>>>> > 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 >>>>>> >>>>> >>>> >>> >>> _______________________________________________ >>> bitcoin-dev mailing list >>> bitcoin-dev@lists.linuxfoundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>> >>> >> ------------------------------ >> >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> > -- > Sent from my Android device with K-9 Mail. Please excuse my brevity. > --001a113f7e7cd4a547051fe9c866 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Eric, that would be, I think, my sequencenumbers2 branch i= n which nSequence is an explicit relative lock-time field (unless the most = significant bit is set). That has absolutely clear semantics. You should co= mment on #6312 where this is being discussed.

On Wed, Sep 16, 2015 at 7:23 PM, Eric= Lombrozo <elombrozo@gmail.com> wrote:
I'd rather replace the whole nSequence thing with a= n explicit relative locktime with clear semantics...but I'm not going t= o fight this one too much.


On September 16, 2015 6:40:06 PM EDT, Btc Drak via bitcoin-dev <= ;bitcoin-dev@lists.linuxfoundation.org> wrote:
Where do we stand now on which=C2=A0sequencenumbers variat= ion to use? We really should make a decision now.

On Fri, Aug 28, 2015 at 12:32 AM, Mar= k Friedenbach via bitcoin-dev <bitcoin-dev@lists.linux= foundation.org> wrote:
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-he= ight. nSequence=3DLOCKTIME_THRESHOLD means 1 second relative lock-height. n= Sequence>=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 interpre= ts 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 bit= s for future use without second-level granularity. More bits could be recov= ered from time-based locktimes by choosing a higher granularity (a soft-for= k change if done correctly).
=
On Tue, Aug 25, 2015 at 3:08 PM, Mark Friede= nbach <mark@friedenbach.org> wrote:
To follow up on this, let's sa= y that you want to be able to have up to 1 year relative lock-times. This c= hoice is somewhat arbitrary and what I would like some input on, but I'= ll come back to this point.

=C2=A0* 1 bit is necessary to= enable/disable relative lock-time.

=C2=A0* 1 = bit is necessary to indicate whether seconds vs blocks as the unit of measu= rement.

=C2=A0* 1 year of time with 1-second granularity = requires 25 bits. However since blocks occur at approximately 10 minute int= ervals on average, having a relative lock-time significantly less than this= interval doesn't make much sense. A granularity of 256 seconds would b= e greater than the Nyquist frequency and requires only 17 bits.

=C2=A0* 1 year of blocks with 1-block granularity requires 16 bits.<= br>

So time-based relative lock time requires about 19 = bits, and block-based relative lock-time requires about 18 bits. That leave= s 13 or 14 bits for other uses.

Assuming a maximum of 1-y= ear 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 would feel uncomfortable going less than a= year for a hard maximum, and am having trouble thinking of any use case th= at would require more than a year of lock-time. Can anyone else think of a = use case that requires >1yr relative lock-time?

= TL;DR

On Sun, Aug 23, 2015 at 7:37 PM, Mark Friedenbach <mark@friede= nbach.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 = how many bits you have left over.

On Aug 23, 2015 7:23 PM, "Jorge Tim=C3=B3n&= quot; <bitcoin-dev@lists.linuxfoundation.org> wrote:
On Mon, Aug 24, 2015 at 3:01 A= M, 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 more=
> than one increment?=C2=A0 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<= br> 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/mail= man/listinfo/bitcoin-dev



_______________________________________________
bitcoin-dev mailing list
= bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev


bitcoin-dev@lists.linuxfound= ation.org
https://lists.linuxfoundation.org/mailma= n/listinfo/bitcoin-dev


--
Sent from my Android device with K-9 Mail. Please excuse my brevity.=

--001a113f7e7cd4a547051fe9c866--