Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 34891B7F for ; Thu, 8 Jun 2017 00:20:29 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ua0-f175.google.com (mail-ua0-f175.google.com [209.85.217.175]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 8E6EC124 for ; Thu, 8 Jun 2017 00:20:25 +0000 (UTC) Received: by mail-ua0-f175.google.com with SMTP id q15so13187817uaa.2 for ; Wed, 07 Jun 2017 17:20:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=LIybttm1gbp5bIsk6jz9sih63wCNZ79c3EVFoBIbEco=; b=cVUBWfd1twwZWivBdJvty3rcypO0kJB0h9DqlBQPwAXKWnLAfAiMjmKYKOy462Rjar lkxT3VXM3M2aZq8goNPrXEEspMquRwG3Qugi61iEuOHpDsENJmX4hLn6msBihQwi5/4O k2cUHOMrGakoYZEHesBsszYafy9VgSEJjA9RkTegv/4i1gYsiS3/jaTytDIXzMjl40KT kLeiW6MEzEQxiSK1tD1DppkVnlZYnDAnDEPWvRUC1zQl3RPoS8Kx/9K/92cd0lPJxLeN PjSGCOCLY8DzdqArzOGll7m86Cr6c0Hk7YkAi/ookJVsz/I13aIG/q1K1+GhNWGw11i5 EGFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=LIybttm1gbp5bIsk6jz9sih63wCNZ79c3EVFoBIbEco=; b=rlamKxbopmrrT264pojgRUcxP2EE0Y4NAQV2cQ6WUTgXhahrxM2efbgyzdxfnuGLbH S/8if2xgEc8BmVYvUu8xoxXzCxIcuq2/+ZcgtCieVCdU+lb9SYgc8hrsAQT9xRJw0LHW 9auDjzBaxjVj0UrSVCkoKUFPuKx9hOclIEFAJSKzJCIMPYvFfNDaSWIDoLQqv5pX1zv5 cKZ18AV93jcNOyBq5fDnHEzPFp2myhTouJu8l7+tbJmHcXkKoi7rkqxfIH8DMpC6YJ7y r4B7Pc95ciP3M+AQDL6cWYhncUZDaE02tFlpZCgq545/zDxbUEH0O2rc3kMtk1uvOokU PSkQ== X-Gm-Message-State: AODbwcDhGZ14e3sPIHC8DO1u9rFOfq0j/lwdTlYaK4hwasiqxhi30PjZ 3/4jItwn8uTdOA4HOe46Xcck0yFmfw== X-Received: by 10.159.48.132 with SMTP id j4mr12841157uab.42.1496881224448; Wed, 07 Jun 2017 17:20:24 -0700 (PDT) MIME-Version: 1.0 Received: by 10.31.157.215 with HTTP; Wed, 7 Jun 2017 17:20:23 -0700 (PDT) In-Reply-To: References: From: Jared Lee Richardson Date: Wed, 7 Jun 2017 17:20:23 -0700 Message-ID: To: James Hilliard Content-Type: multipart/alternative; boundary="f403045e3edea78041055167d136" X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM, HTML_MESSAGE, LOTS_OF_MONEY, RCVD_IN_DNSWL_NONE autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Thu, 08 Jun 2017 00:30:28 +0000 Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] User Activated Soft Fork Split Protection X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Jun 2017 00:20:29 -0000 --f403045e3edea78041055167d136 Content-Type: text/plain; charset="UTF-8" > Not really, there are a few relatively simple techniques such as RBF > which can be leveraged to get confirmations on on-side before double > spending on another. Once a transaction is confirmed on the non-BIP148 > chain then the high fee transactions can be made on only the BIP148 > side of the split using RBF. Ah, so the BIP148 client handles this on behalf of its less technical users on their behalf then, yes? > Exchanges will likely do this splitting > automatically for uses as well. Sure, Exchanges are going to dedicate hundreds of developer hours and thousands of support hours to support something that they've repeatedly told everyone must have replay protection to be supported. They're going to do this because 8% of nodes and <0.5% of miners say they'll be rewarded richly. Somehow I find that hard to believe. Besides, if the BIP148 client does it for them, they wouldn't have to dedicate those hundreds of developer hours. Right? I can't imagine how this logic is getting you from where the real data is to the assumption that an economic majority will push BIP148 into being such a more valuable chain that switching chains will be attractive to enough miners. There's got to be some real data that convinces you of this somewhere? > Both are issues, but wipeout risk is different, the ETH/ETC split for > example didn't have any wipeout risk for either side the same is not > true for BIP148(and it is the non-BIP148 side that carries the risk of > chain wipeout). Wipeout risk is a serious issue when 45% of the miners support one chain and 55% support the other chain. Segwit doesn't even have 35% of the miners; There's no data or statements anywhere that indicate that UASF is going to reach the point where wipeout risk is even comparable to abandonment risk. > Yes, miners aren't likely to waste operational mining costs, that's > ultimately why miners would follow the BIP148 side of the chain > assuming it has sufficient economic support or if it's more profitable > to mine. To convince miners you would have to have some data SOMEWHERE supporting the economic majority argument. Is there any such data? > segwit2x has more issues since the HF part requires users to reach consensus It doesn't have those issues during the segwit activation, ergo there is no reason for segwit-activation problems to take priority over the very real hardfork activation problems. > That's a political reason not a technical reason. In a consensus system they are frequently the same, unfortunately. Technical awesomeness without people agreeing = zero consensus. So the choice is either to "technically" break the consensus without a super-majority and see what happens, or to go with the choice that has real data showing the most consensus and hope the tiny minority chain actually dies off. Jared On Wed, Jun 7, 2017 at 5:01 PM, James Hilliard wrote: > On Wed, Jun 7, 2017 at 6:43 PM, Jared Lee Richardson > wrote: > >> BIP148 however is a consensus change that can > >> be rectified if it gets more work, this would act as an additional > >> incentive for mine the BIP148 side since there would be no wipeout > >> risk there. > > > > This statement is misleading. Wipeout risks don't apply to any consensus > > changes; It is a consensus change, it can only be abandoned. The BIP148 > > chain carries just as many risks of being abandoned or even more with > > segwit2x on the table. No miner would consider "wipeout risk" an > advantage > > when the real threat is chain abandonment. > Both are issues, but wipeout risk is different, the ETH/ETC split for > example didn't have any wipeout risk for either side the same is not > true for BIP148(and it is the non-BIP148 side that carries the risk of > chain wipeout). > > > >> Higher transaction fees on a minority chain can compensate miners for > >> a lower price which would likely be enough to get the BIP148 chain to > >> a difficulty reduction. > > > > Higher transaction fees suffers the same problem as exchange support > does. > > Without replay protection, it is very difficult for any average user to > > force transactions onto one chain or the other. Thus, without replay > > protection, the UASF chain is unlikely to develop any viable fee market; > Its > > few miners 99% of the time will simply choose from the highest fees that > > were already available to the other chain, which is basically no > advantage > > at all. > Not really, there are a few relatively simple techniques such as RBF > which can be leveraged to get confirmations on on-side before double > spending on another. Once a transaction is confirmed on the non-BIP148 > chain then the high fee transactions can be made on only the BIP148 > side of the split using RBF. Exchanges will likely do this splitting > automatically for uses as well. > > > >> ETC replay protection was done after the fork on an as > >> needed basis(there are multiple reliable techniques that can be used > >> to split UTXO's), the same can happen with BIP148 and it is easier to > >> do with Bitcoin than with the ETH/ETC split IMO. > > > > ETC replay protection was added because they were already a hardfork and > > without it they would not have had a viable chain. BIP148 is not > supposed > > to be a hardfork, and if it added replay protection to remain viable it > > would lose the frequently touted "wipeout advantage" as well as the > ability > > to call itself a softfork. And are you seriously suggesting that what > > happened with ETC and ETH is a desirable and good situation for Bitcoin, > and > > that UASF is ETC? > There wasn't proper replay protection at split time for ETH/ETC since > normal transactions would get executed on both sides originally, > however replay protection was added by wallets(mainly using splitting > contracts). I don't think a split is desirable however, which is why > I've proposed this BIP. > > > >> A big reason BIP148 still has support is because up until SegWit > >> actually activates there's no guarantee segwit2mb will actually have > >> the necessary support to activate SegWit. > > > > For a miners blowing through six million dollars a day in mining > operational > > costs, that's a pretty crappy reason. Serious miners can't afford to > prop > > up a non-viable chain based on philosophy or maybes. BIP148 is based > > entirely upon people who aren't putting anything on the line trying to > > convince others to take the huge risks for them. With deceptively > > fallacious logic, in my opinion. > Yes, miners aren't likely to waste operational mining costs, that's > ultimately why miners would follow the BIP148 side of the chain > assuming it has sufficient economic support or if it's more profitable > to mine. > > > > Even segwit2x is based on the assumption that all miners can reach > > consensus. Break that assumption and segwit2x will have the same > problems > > as UASF. > segwit2x has more issues since the HF part requires users to reach > consensus > > > >> This is largely an issue due to segwit2x's bundling, if the SW and HF > >> part of segwit2x were unbundled then there would be no reason to delay > >> BIP91 activation > > > > They are bundled. Segwit alone doesn't have the desired overwhelming > > consensus, unless core wishes to fork 71% to 29%, and maybe not even that > > high. That's the technical reason, and they can't be unbundled without > > breaking that consensus. > That's a political reason not a technical reason. > > > > Jared > > > > > > On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard < > james.hilliard1@gmail.com> > > wrote: > >> > >> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson < > jaredr26@gmail.com> > >> wrote: > >> >> There are 2 primary factors involved here, economic support and > >> > hashpower either of which is enough to make a permanent chain split > >> > unlikely, miners will mine whichever chain is most profitable(see > >> > ETH/ETC hashpower profitability equilibrium for an example of how this > >> > works in practice) > >> > > >> > That's not a comparable example. ETC did not face potentially years > of > >> > slow > >> > blocktimes before it normalized, whereas BIP148 is on track to do > >> > exactly > >> > that. Moreover, ETC represented a fundamental break from the majority > >> > consensus that could not be rectified, whereas BIP148 represents only > a > >> > minority attempt to accelerate something that an overwhelming majority > >> > of > >> > miners have already agreed to activate under segwit2x. Lastly ETC was > >> > required to add replay protection, just like any minority fork > proposed > >> > by > >> > any crypto-currency has been, something that BIP148 both lacks and > >> > refuses > >> > to add or even acknowledge the necessity of. Without replay > protection, > >> > ETC > >> > could not have become profitable enough to be a viable minority chain. > >> > If > >> > BIP148's chain is not the majority chain and it does not have replay > >> > protection, it will face the same problems, but that required replay > >> > protection will turn it into a hardfork. This will be a very bad > >> > position > >> > for UASF supporters to find themselves in - Either hardfork and hope > the > >> > price is higher and the majority converts, or die as the minority > chain > >> > with > >> > no reliable methods of economic conversion. > >> Higher transaction fees on a minority chain can compensate miners for > >> a lower price which would likely be enough to get the BIP148 chain to > >> a difficulty reduction. BIP148 however is a consensus change that can > >> be rectified if it gets more work, this would act as an additional > >> incentive for mine the BIP148 side since there would be no wipeout > >> risk there. ETC replay protection was done after the fork on an as > >> needed basis(there are multiple reliable techniques that can be used > >> to split UTXO's), the same can happen with BIP148 and it is easier to > >> do with Bitcoin than with the ETH/ETC split IMO. > >> > > >> > I believe, but don't have data to back this, that most of the BIP148 > >> > insistence comes not from a legitimate attempt to gain consensus (or > >> > else > >> > they would either outright oppose segwit2mb for its hardfork, or they > >> > would > >> > outright support it), but rather from an attempt for BIP148 supporters > >> > to > >> > save face for BIP148 being a failure. If I'm correct, that's a > terrible > >> > and > >> > highly non-technical reason for segwit2mb to bend over backwards > >> > attempting > >> > to support BIP148's attempt to save face. > >> A big reason BIP148 still has support is because up until SegWit > >> actually activates there's no guarantee segwit2mb will actually have > >> the necessary support to activate SegWit. > >> > > >> >> The main issue is just one of activation timelines, BIP91 as > >> > is takes too long to activate unless started ahead of the existing > >> > segwit2x schedule and it's unlikely that BIP148 will get pushed back > >> > any further. > >> > > >> > Even if I'm not correct on the above, I and others find it hard to > >> > accept > >> > that this timeline conflict is segwit2x's fault. Segwit2x has both > some > >> > flexibility and broad support that crosses contentious pro-segwit and > >> > pro-blocksize-increase divisions that have existed for two years. > >> > BIP148 is > >> > attempting to hold segwit2x's timelines and code hostage by claiming > >> > inflexibility and claiming broad support, and not only are neither of > >> > those > >> > assertions are backed by real data, BIP148 (by being so inflexible) is > >> > pushing a position that deepens the divides between those groups. For > >> > there > >> > to be technical reasons for compatibility (so long as there are > >> > tradeoffs, > >> > which there are), there needs to be hard data showing that BIP148 is a > >> > viable minority fork that won't simply die off on its own. > >> This is largely an issue due to segwit2x's bundling, if the SW and HF > >> part of segwit2x were unbundled then there would be no reason to delay > >> BIP91 activation, this is especially a problem since it takes a good > >> deal of time to properly code and test a HF. Unfortunately segwit2x > >> has been quite inflexible in regards to the bundling aspect even > >> though there are clearly no technical reasons for it to be there. > >> > > >> > Jared > >> > > >> > > >> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard > >> > > >> > wrote: > >> >> > >> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson > >> >> > >> >> wrote: > >> >> > Could this risk mitigation measure be an optional flag? And if so, > >> >> > could it+BIP91 signal on a different bit than bit4? > >> >> It's fairly trivial for miners to signal for BIP91 on bit4 or a > >> >> different bit at the same time as the code is trivial enough to > >> >> combine > >> >> > > >> >> > The reason being, if for some reason the segwit2x activation cannot > >> >> > take place in time, it would be preferable for miners to have a > more > >> >> > standard approach to activation that requires stronger consensus > and > >> >> > may be more forgiving than BIP148. If the segwit2x activation is > on > >> >> > time to cooperate with BIP148, it could be signaled through the > >> >> > non-bit4 approach and everything could go smoothly. Thoughts on > that > >> >> > idea? It may add more complexity and more developer time, but may > >> >> > also address your concerns among others. > >> >> This does give miners another approach to activate segwit ahead of > >> >> BIP148, if segwit2x activation is rolled out and activated > immediately > >> >> then this would not be needed however based on the timeline here > >> >> https://segwit2x.github.io/ it would not be possible for BIP91 to > >> >> enforce mandatory signalling ahead of BIP148. Maybe that can be > >> >> changed though, I've suggested an immediate rollout with a > placeholder > >> >> client timeout instead of the HF code initially in order to > accelerate > >> >> that. > >> >> > > >> >> >> Since this BIP > >> >> >> only activates with a clear miner majority it should not increase > >> >> >> the > >> >> >> risk of an extended chain split. > >> >> > > >> >> > The concern I'm raising is more about the psychology of giving > BIP148 > >> >> > a sense of safety that may not be valid. Without several more > steps, > >> >> > BIP148 is definitely on track to be a risky chainsplit, and without > >> >> > segwit2x it will almost certainly be a small minority chain. > (Unless > >> >> > the segwit2x compromise falls apart before then, and even in that > >> >> > case > >> >> > it is likely to be a minority chain) > >> >> There are 2 primary factors involved here, economic support and > >> >> hashpower either of which is enough to make a permanent chain split > >> >> unlikely, miners will mine whichever chain is most profitable(see > >> >> ETH/ETC hashpower profitability equilibrium for an example of how > this > >> >> works in practice) however there may be lag time immediately after > the > >> >> split if there is an economic majority but not a hashpower majority > >> >> initially. This is risk mitigation that only requires miners support > >> >> however. The main issue is just one of activation timelines, BIP91 as > >> >> is takes too long to activate unless started ahead of the existing > >> >> segwit2x schedule and it's unlikely that BIP148 will get pushed back > >> >> any further. > >> >> > > >> >> > Jared > >> >> > > >> >> > > >> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard > >> >> > wrote: > >> >> >> I don't really see how this would increase the likelihood of an > >> >> >> extended chain split assuming BIP148 is going to have > >> >> >> non-insignificant economic backing. This BIP is designed to > provide > >> >> >> a > >> >> >> risk mitigation measure that miners can safely deploy. Since this > >> >> >> BIP > >> >> >> only activates with a clear miner majority it should not increase > >> >> >> the > >> >> >> risk of an extended chain split. At this point it is not > completely > >> >> >> clear how much economic support there is for BIP148 but support > >> >> >> certainly seems to be growing and we have nearly 2 months until > >> >> >> BIP148 > >> >> >> activation. I intentionally used a shorter activation period here > so > >> >> >> that decisions by miners can be made close to the BIP148 > activation > >> >> >> date. > >> >> >> > >> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richardson > >> >> >> wrote: > >> >> >>> I think this BIP represents a gamble, and the gamble may not be a > >> >> >>> good > >> >> >>> one. The gamble here is that if the segwit2x changes are rolled > >> >> >>> out > >> >> >>> on time, and if the signatories accept the bit4 + bit1 signaling > >> >> >>> proposals within BIP91, the launch will go smoother, as intended. > >> >> >>> But > >> >> >>> conversely, if either the segwit2x signatories balk about the > Bit1 > >> >> >>> signaling OR if the timelines for segwit2mb are missed even by a > >> >> >>> bit, > >> >> >>> it may cause the BIP148 chainsplit to be worse than it would be > >> >> >>> without. Given the frequent concerns raised in multiple places > >> >> >>> about > >> >> >>> the aggressiveness of the segwit2x timelines, including the > >> >> >>> non-hardfork timelines, this does not seem like a great gamble to > >> >> >>> be > >> >> >>> making. > >> >> >>> > >> >> >>> The reason I say it may make the chainsplit be worse than it > would > >> >> >>> otherwise be is that it may provide a false sense of safety for > >> >> >>> BIP148 > >> >> >>> that currently does not currently exist(and should not, as it is > a > >> >> >>> chainsplit). That sense of safety would only be legitimate if > the > >> >> >>> segwit2x signatories were on board, and the segwit2x code > >> >> >>> effectively > >> >> >>> enforced BIP148 simultaneously, neither of which are guaranteed. > >> >> >>> If > >> >> >>> users and more miners had a false sense that BIP148 was *not* > going > >> >> >>> to > >> >> >>> chainsplit from default / segwit2x, they might not follow the > news > >> >> >>> if > >> >> >>> suddenly the segwit2x plan were delayed for a few days. While > any > >> >> >>> additional support would definitely be cheered on by BIP148 > >> >> >>> supporters, the practical reality might be that this proposal > would > >> >> >>> take BIP148 from the "unlikely to have any viable chain after > flag > >> >> >>> day > >> >> >>> without segwit2x" category into the "small but viable minority > >> >> >>> chain" > >> >> >>> category, and even worse, it might strengthen the chainsplit just > >> >> >>> days > >> >> >>> before segwit is activated on BOTH chains, putting the BIP148 > >> >> >>> supporters on the wrong pro-segwit, but still-viable chain. > >> >> >>> > >> >> >>> If Core had taken a strong stance to include BIP148 into the > >> >> >>> client, > >> >> >>> and if BIP148 support were much much broader, I would feel > >> >> >>> differently > >> >> >>> as the gamble would be more likely to discourage a chainsplit (By > >> >> >>> forcing the acceleration of segwit2x) rather than encourage it > (by > >> >> >>> strengthening an extreme minority chainsplit that may wind up on > >> >> >>> the > >> >> >>> wrong side of two segwit-activated chains). As it stands now, > this > >> >> >>> seems like a very dangerous attempt to compromise with a small > but > >> >> >>> vocal group that are the ones creating the threat to begin with. > >> >> >>> > >> >> >>> Jared > >> >> >>> > >> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hilliard via bitcoin-dev > >> >> >>> wrote: > >> >> >>>> Due to the proposed calendar(https://segwit2x.github.io/) for > the > >> >> >>>> SegWit2x agreement being too slow to activate SegWit mandatory > >> >> >>>> signalling ahead of BIP148 using BIP91 I would like to propose > >> >> >>>> another > >> >> >>>> option that miners can use to prevent a chain split ahead of the > >> >> >>>> Aug > >> >> >>>> 1st BIP148 activation date. > >> >> >>>> > >> >> >>>> The splitprotection soft fork is essentially BIP91 but using > BIP8 > >> >> >>>> instead of BIP9 with a lower activation threshold and immediate > >> >> >>>> mandatory signalling lock-in. This allows for a majority of > miners > >> >> >>>> to > >> >> >>>> activate mandatory SegWit signalling and prevent a potential > chain > >> >> >>>> split ahead of BIP148 activation. > >> >> >>>> > >> >> >>>> This BIP allows for miners to respond to market forces quickly > >> >> >>>> ahead > >> >> >>>> of BIP148 activation by signalling for splitprotection. Any > miners > >> >> >>>> already running BIP148 should be encouraged to use > >> >> >>>> splitprotection. > >> >> >>>> > >> >> >>>> 
> >> >> >>>>   BIP: splitprotection
> >> >> >>>>   Layer: Consensus (soft fork)
> >> >> >>>>   Title: User Activated Soft Fork Split Protection
> >> >> >>>>   Author: James Hilliard 
> >> >> >>>>   Comments-Summary: No comments yet.
> >> >> >>>>   Comments-URI:
> >> >> >>>>   Status: Draft
> >> >> >>>>   Type: Standards Track
> >> >> >>>>   Created: 2017-05-22
> >> >> >>>>   License: BSD-3-Clause
> >> >> >>>>            CC0-1.0
> >> >> >>>>
> >> >> >>>> > >> >> >>>> ==Abstract== > >> >> >>>> > >> >> >>>> This document specifies a coordination mechanism for a simple > >> >> >>>> majority > >> >> >>>> of miners to prevent a chain split ahead of BIP148 activation. > >> >> >>>> > >> >> >>>> ==Definitions== > >> >> >>>> > >> >> >>>> "existing segwit deployment" refer to the BIP9 "segwit" > deployment > >> >> >>>> using bit 1, between November 15th 2016 and November 15th 2017 > to > >> >> >>>> activate BIP141, BIP143 and BIP147. > >> >> >>>> > >> >> >>>> ==Motivation== > >> >> >>>> > >> >> >>>> The biggest risk of BIP148 is an extended chain split, this BIP > >> >> >>>> provides a way for a simple majority of miners to eliminate that > >> >> >>>> risk. > >> >> >>>> > >> >> >>>> This BIP provides a way for a simple majority of miners to > >> >> >>>> coordinate > >> >> >>>> activation of the existing segwit deployment with less than 95% > >> >> >>>> hashpower before BIP148 activation. Due to time constraints > unless > >> >> >>>> immediately deployed BIP91 will likely not be able to enforce > >> >> >>>> mandatory signalling of segwit before the Aug 1st activation of > >> >> >>>> BIP148. This BIP provides a method for rapid miner activation of > >> >> >>>> SegWit mandatory signalling ahead of the BIP148 activation date. > >> >> >>>> Since > >> >> >>>> the primary goal of this BIP is to reduce the chance of an > >> >> >>>> extended > >> >> >>>> chain split as much as possible we activate using a simple miner > >> >> >>>> majority of 65% over a 504 block interval rather than a higher > >> >> >>>> percentage. This BIP also allows miners to signal their > intention > >> >> >>>> to > >> >> >>>> run BIP148 in order to prevent a chain split. > >> >> >>>> > >> >> >>>> ==Specification== > >> >> >>>> > >> >> >>>> While this BIP is active, all blocks must set the nVersion > header > >> >> >>>> top > >> >> >>>> 3 bits to 001 together with bit field (1<<1) (according to the > >> >> >>>> existing segwit deployment). Blocks that do not signal as > required > >> >> >>>> will be rejected. > >> >> >>>> > >> >> >>>> ==Deployment== > >> >> >>>> > >> >> >>>> This BIP will be deployed by "version bits" with a 65%(this can > be > >> >> >>>> adjusted if desired) activation threshold BIP9 with the name > >> >> >>>> "splitprotecion" and using bit 2. > >> >> >>>> > >> >> >>>> This BIP starts immediately and is a BIP8 style soft fork since > >> >> >>>> mandatory signalling will start on midnight August 1st 2017 > (epoch > >> >> >>>> time 1501545600) regardless of whether or not this BIP has > reached > >> >> >>>> its > >> >> >>>> own signalling threshold. This BIP will cease to be active when > >> >> >>>> segwit > >> >> >>>> is locked-in. > >> >> >>>> > >> >> >>>> === Reference implementation === > >> >> >>>> > >> >> >>>> 
> >> >> >>>> // Check if Segregated Witness is Locked In
> >> >> >>>> bool IsWitnessLockedIn(const CBlockIndex* pindexPrev, const
> >> >> >>>> Consensus::Params& params)
> >> >> >>>> {
> >> >> >>>>     LOCK(cs_main);
> >> >> >>>>     return (VersionBitsState(pindexPrev, params,
> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbitscache) ==
> >> >> >>>> THRESHOLD_LOCKED_IN);
> >> >> >>>> }
> >> >> >>>>
> >> >> >>>> // SPLITPROTECTION mandatory segwit signalling.
> >> >> >>>> if ( VersionBitsState(pindex->pprev,
> chainparams.GetConsensus(),
> >> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTION, versionbitscache) ==
> >> >> >>>> THRESHOLD_LOCKED_IN &&
> >> >> >>>>      !IsWitnessLockedIn(pindex->pprev,
> chainparams.GetConsensus())
> >> >> >>>> &&
> >> >> >>>> // Segwit is not locked in
> >> >> >>>>      !IsWitnessEnabled(pindex->pprev,
> chainparams.GetConsensus())
> >> >> >>>> )
> >> >> >>>> //
> >> >> >>>> and is not active.
> >> >> >>>> {
> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
> VERSIONBITS_TOP_MASK)
> >> >> >>>> ==
> >> >> >>>> VERSIONBITS_TOP_BITS;
> >> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
> >> >> >>>> must
> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >> >>>> "bad-no-segwit");
> >> >> >>>>     }
> >> >> >>>> }
> >> >> >>>>
> >> >> >>>> // BIP148 mandatory segwit signalling.
> >> >> >>>> int64_t nMedianTimePast = pindex->GetMedianTimePast();
> >> >> >>>> if ( (nMedianTimePast >= 1501545600) &&  // Tue 01 Aug 2017
> >> >> >>>> 00:00:00
> >> >> >>>> UTC
> >> >> >>>>      (nMedianTimePast <= 1510704000) &&  // Wed 15 Nov 2017
> >> >> >>>> 00:00:00
> >> >> >>>> UTC
> >> >> >>>>      (!IsWitnessLockedIn(pindex->pprev,
> >> >> >>>> chainparams.GetConsensus())
> >> >> >>>> &&
> >> >> >>>>  // Segwit is not locked in
> >> >> >>>>       !IsWitnessEnabled(pindex->pprev,
> >> >> >>>> chainparams.GetConsensus())) )
> >> >> >>>>  // and is not active.
> >> >> >>>> {
> >> >> >>>>     bool fVersionBits = (pindex->nVersion &
> VERSIONBITS_TOP_MASK)
> >> >> >>>> ==
> >> >> >>>> VERSIONBITS_TOP_BITS;
> >> >> >>>>     bool fSegbit = (pindex->nVersion &
> >> >> >>>> VersionBitsMask(chainparams.GetConsensus(),
> >> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) != 0;
> >> >> >>>>     if (!(fVersionBits && fSegbit)) {
> >> >> >>>>         return state.DoS(0, error("ConnectBlock(): relayed block
> >> >> >>>> must
> >> >> >>>> signal for segwit, please upgrade"), REJECT_INVALID,
> >> >> >>>> "bad-no-segwit");
> >> >> >>>>     }
> >> >> >>>> }
> >> >> >>>>
> >> >> >>>> > >> >> >>>> > >> >> >>>> > >> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14... > jameshilliard:splitprotection-v0.14.1 > >> >> >>>> > >> >> >>>> ==Backwards Compatibility== > >> >> >>>> > >> >> >>>> This deployment is compatible with the existing "segwit" bit 1 > >> >> >>>> deployment scheduled between midnight November 15th, 2016 and > >> >> >>>> midnight > >> >> >>>> November 15th, 2017. This deployment is also compatible with the > >> >> >>>> existing BIP148 deployment. This BIP is compatible with BIP91 > only > >> >> >>>> if > >> >> >>>> BIP91 activates before it and before BIP148. Miners will need to > >> >> >>>> upgrade their nodes to support splitprotection otherwise they > may > >> >> >>>> build on top of an invalid block. While this bip is active users > >> >> >>>> should either upgrade to splitprotection or wait for additional > >> >> >>>> confirmations when accepting payments. > >> >> >>>> > >> >> >>>> ==Rationale== > >> >> >>>> > >> >> >>>> Historically we have used IsSuperMajority() to activate soft > forks > >> >> >>>> such as BIP66 which has a mandatory signalling requirement for > >> >> >>>> miners > >> >> >>>> once activated, this ensures that miners are aware of new rules > >> >> >>>> being > >> >> >>>> enforced. This technique can be leveraged to lower the > signalling > >> >> >>>> threshold of a soft fork while it is in the process of being > >> >> >>>> deployed > >> >> >>>> in a backwards compatible way. We also use a BIP8 style timeout > to > >> >> >>>> ensure that this BIP is compatible with BIP148 and that BIP148 > >> >> >>>> compatible mandatory signalling activates regardless of miner > >> >> >>>> signalling levels. > >> >> >>>> > >> >> >>>> By orphaning non-signalling blocks during the BIP9 bit 1 > "segwit" > >> >> >>>> deployment, this BIP can cause the existing "segwit" deployment > to > >> >> >>>> activate without needing to release a new deployment. As we > >> >> >>>> approach > >> >> >>>> BIP148 activation it may be desirable for a majority of miners > to > >> >> >>>> have > >> >> >>>> a method that will ensure that there is no chain split. > >> >> >>>> > >> >> >>>> ==References== > >> >> >>>> > >> >> >>>> > >> >> >>>> > >> >> >>>> *[https://lists.linuxfoundation.org/pipermail/ > bitcoin-dev/2017-March/013714.html > >> >> >>>> Mailing list discussion] > >> >> >>>> > >> >> >>>> > >> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main. > cpp#L1281-L1283 > >> >> >>>> P2SH flag day activation] > >> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits with timeout and delay]] > >> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Script Hash]] > >> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced threshold Segwit MASF]] > >> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated Witness (Consensus > >> >> >>>> layer)]] > >> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction Signature Verification > >> >> >>>> for > >> >> >>>> Version 0 Witness Program]] > >> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing with dummy stack element > >> >> >>>> malleability]] > >> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory activation of segwit > >> >> >>>> deployment]] > >> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated Witness (second > >> >> >>>> deployment)]] > >> >> >>>> *[https://bitcoincore.org/en/2016/01/26/segwit-benefits/ Segwit > >> >> >>>> benefits] > >> >> >>>> > >> >> >>>> ==Copyright== > >> >> >>>> > >> >> >>>> This document is dual licensed as BSD 3-clause, and Creative > >> >> >>>> Commons > >> >> >>>> CC0 1.0 Universal. > >> >> >>>> _______________________________________________ > >> >> >>>> bitcoin-dev mailing list > >> >> >>>> bitcoin-dev@lists.linuxfoundation.org > >> >> >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > >> > > >> > > > > > > --f403045e3edea78041055167d136 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
>=C2=A0Not really, the= re are a few relatively simple techniques such as RBF
> which can be leverage= d to get confirmations on on-side before double
> spending on another. Once a= transaction is confirmed on the non-BIP148
> chain then the high fee transac= tions can be made on only the BIP148
<= span style=3D"font-size:12.8px">> side of the split using RBF.=C2=A0
=
Ah, so the BIP148 client handles this on behalf of its less technical u= sers on their behalf then, yes?

>=C2=A0=C2=A0Exchanges will likely do this splitting
> automatically f= or uses as well.

Sure, Excha= nges are going to dedicate hundreds of developer hours and thousands of sup= port hours to support something that they've repeatedly told everyone m= ust have replay protection to be supported.=C2=A0 They're going to do t= his because 8% of nodes and <0.5% of miners say they'll be rewarded = richly.=C2=A0 Somehow I find that hard to believe.

Besides, if the B= IP148 client does it for them, they wouldn't have to dedicate those hun= dreds of developer hours.=C2=A0 Right?

I can't imagine how this = logic is getting you from where the real data is to the assumption that an = economic majority will push BIP148 into being such a more valuable chain th= at switching chains will be attractive to enough miners.=C2=A0 There's = got to be some real data that convinces you of this somewhere?

>= =C2=A0Both are issues, but wipeout = risk is different, the ETH/ETC split for
> example didn't have any wipeou= t risk for either side the same is not
> true for BIP148(and it is the non-BI= P148 side that carries the risk of
> chain wipeout).

Wipeout risk is a serious issue when 45% of the mine= rs support one chain and 55% support the other chain.=C2=A0 Segwit doesn= 9;t even have 35% of the miners; There's no data or statements anywhere= that indicate that UASF is going to reach the point where wipeout risk is = even comparable to abandonment risk.

>=C2=A0Yes, miners aren't likely to waste operational minin= g costs, that's
> ultimately why miners would follow the BIP148 side of t= he chain
> assuming it has sufficient economic support or if it's more pr= ofitable
> to mine.

To convinc= e miners you would have to have some data SOMEWHERE supporting the economic= majority argument.=C2=A0 Is there any such data?

&= gt;=C2=A0segwit2x has more issues s= ince the HF part requires users to reach consensus

It doesn't have those issues during the segwit a= ctivation, ergo there is no reason for segwit-activation problems to take p= riority over the very real hardfork activation problems.

>=C2=A0<= /span>That's a political reason not a = technical reason.

In a conse= nsus system they are frequently the same, unfortunately.=C2=A0 Technical aw= esomeness without people agreeing =3D zero consensus.=C2=A0 So the choice i= s either to "technically" break the consensus without a super-maj= ority and see what happens, or to go with the choice that has real data sho= wing the most consensus and hope the tiny minority chain actually dies off.=

Jared

On Wed, Jun 7, 2017 at 5:01 PM, James Hilliard <james.hilliard1@gmail.com> wrote:
On Wed, Jun 7, 2017 at 6:43 PM, Jared Lee Richards= on <jaredr26@gmail.com> wro= te:
>> BIP148 however is a consensus change that can
>> be rectified if it gets more work, this would act as an additional=
>> incentive for mine the BIP148 side since there would be no wipeout=
>> risk there.
>
> This statement is misleading.=C2=A0 Wipeout risks don't apply to a= ny consensus
> changes; It is a consensus change, it can only be abandoned.=C2=A0 The= BIP148
> chain carries just as many risks of being abandoned or even more with<= br> > segwit2x on the table.=C2=A0 No miner would consider "wipeout ris= k" an advantage
> when the real threat is chain abandonment.
Both are issues, but wipeout risk is different, the ETH/ETC split fo= r
example didn't have any wipeout risk for either side the same is not true for BIP148(and it is the non-BIP148 side that carries the risk of
chain wipeout).
>
>> Higher transaction fees on a minority chain can compensate miners = for
>> a lower price which would likely be enough to get the BIP148 chain= to
>> a difficulty reduction.
>
> Higher transaction fees suffers the same problem as exchange support d= oes.
> Without replay protection, it is very difficult for any average user t= o
> force transactions onto one chain or the other.=C2=A0 Thus, without re= play
> protection, the UASF chain is unlikely to develop any viable fee marke= t; Its
> few miners 99% of the time will simply choose from the highest fees th= at
> were already available to the other chain, which is basically no advan= tage
> at all.
Not really, there are a few relatively simple techniques such as RBF=
which can be leveraged to get confirmations on on-side before double
spending on another. Once a transaction is confirmed on the non-BIP148
chain then the high fee transactions can be made on only the BIP148
side of the split using RBF. Exchanges will likely do this splitting
automatically for uses as well.
>
>>=C2=A0 ETC replay protection was done after the fork on an as
>> needed basis(there are multiple reliable techniques that can be us= ed
>> to split UTXO's), the same can happen with BIP148 and it is ea= sier to
>> do with Bitcoin than with the ETH/ETC split IMO.
>
> ETC replay protection was added because they were already a hardfork a= nd
> without it they would not have had a viable chain.=C2=A0 BIP148 is not= supposed
> to be a hardfork, and if it added replay protection to remain viable i= t
> would lose the frequently touted "wipeout advantage" as well= as the ability
> to call itself a softfork.=C2=A0 And are you seriously suggesting that= what
> happened with ETC and ETH is a desirable and good situation for Bitcoi= n, and
> that UASF is ETC?
There wasn't proper replay protection at split time for ETH/ETC = since
normal transactions would get executed on both sides originally,
however replay protection was added by wallets(mainly using splitting
contracts). I don't think a split is desirable however, which is why I've proposed this BIP.
>
>> A big reason BIP148 still has support is because up until SegWit >> actually activates there's no guarantee segwit2mb will actuall= y have
>> the necessary support to activate SegWit.
>
> For a miners blowing through six million dollars a day in mining opera= tional
> costs, that's a pretty crappy reason.=C2=A0 Serious miners can'= ;t afford to prop
> up a non-viable chain based on philosophy or maybes.=C2=A0 BIP148 is b= ased
> entirely upon people who aren't putting anything on the line tryin= g to
> convince others to take the huge risks for them.=C2=A0 With deceptivel= y
> fallacious logic, in my opinion.
Yes, miners aren't likely to waste operational mining costs, tha= t's
ultimately why miners would follow the BIP148 side of the chain
assuming it has sufficient economic support or if it's more profitable<= br> to mine.
>
> Even segwit2x is based on the assumption that all miners can reach
> consensus.=C2=A0 Break that assumption and segwit2x will have the same= problems
> as UASF.
segwit2x has more issues since the HF part requires users to reach c= onsensus
>
>> This is largely an issue due to segwit2x's bundling, if the SW= and HF
>> part of segwit2x were unbundled then there would be no reason to d= elay
>> BIP91 activation
>
> They are bundled.=C2=A0 Segwit alone doesn't have the desired over= whelming
> consensus, unless core wishes to fork 71% to 29%, and maybe not even t= hat
> high.=C2=A0 That's the technical reason, and they can't be unb= undled without
> breaking that consensus.
That's a political reason not a technical reason.
>
> Jared
>
>
> On Wed, Jun 7, 2017 at 4:11 PM, James Hilliard <james.hilliard1@gmail.com>
> wrote:
>>
>> On Wed, Jun 7, 2017 at 5:53 PM, Jared Lee Richardson <jaredr26@gmail.com>
>> wrote:
>> >> There are 2 primary factors involved here, economic suppo= rt and
>> > hashpower either of which is enough to make a permanent chain= split
>> > unlikely, miners will mine whichever chain is most profitable= (see
>> > ETH/ETC hashpower profitability equilibrium for an example of= how this
>> > works in practice)
>> >
>> > That's not a comparable example.=C2=A0 ETC did not face p= otentially years of
>> > slow
>> > blocktimes before it normalized, whereas BIP148 is on track t= o do
>> > exactly
>> > that.=C2=A0 Moreover, ETC represented a fundamental break fro= m the majority
>> > consensus that could not be rectified, whereas BIP148 represe= nts only a
>> > minority attempt to accelerate something that an overwhelming= majority
>> > of
>> > miners have already agreed to activate under segwit2x.=C2=A0 = Lastly ETC was
>> > required to add replay protection, just like any minority for= k proposed
>> > by
>> > any crypto-currency has been, something that BIP148 both lack= s and
>> > refuses
>> > to add or even acknowledge the necessity of.=C2=A0 Without re= play protection,
>> > ETC
>> > could not have become profitable enough to be a viable minori= ty chain.
>> > If
>> > BIP148's chain is not the majority chain and it does not = have replay
>> > protection, it will face the same problems, but that required= replay
>> > protection will turn it into a hardfork.=C2=A0 This will be a= very bad
>> > position
>> > for UASF supporters to find themselves in - Either hardfork a= nd hope the
>> > price is higher and the majority converts, or die as the mino= rity chain
>> > with
>> > no reliable methods of economic conversion.
>> Higher transaction fees on a minority chain can compensate miners = for
>> a lower price which would likely be enough to get the BIP148 chain= to
>> a difficulty reduction. BIP148 however is a consensus change that = can
>> be rectified if it gets more work, this would act as an additional=
>> incentive for mine the BIP148 side since there would be no wipeout=
>> risk there. ETC replay protection was done after the fork on an as=
>> needed basis(there are multiple reliable techniques that can be us= ed
>> to split UTXO's), the same can happen with BIP148 and it is ea= sier to
>> do with Bitcoin than with the ETH/ETC split IMO.
>> >
>> > I believe, but don't have data to back this, that most of= the BIP148
>> > insistence comes not from a legitimate attempt to gain consen= sus (or
>> > else
>> > they would either outright oppose segwit2mb for its hardfork,= or they
>> > would
>> > outright support it), but rather from an attempt for BIP148 s= upporters
>> > to
>> > save face for BIP148 being a failure.=C2=A0 If I'm correc= t, that's a terrible
>> > and
>> > highly non-technical reason for segwit2mb to bend over backwa= rds
>> > attempting
>> > to support BIP148's attempt to save face.
>> A big reason BIP148 still has support is because up until SegWit >> actually activates there's no guarantee segwit2mb will actuall= y have
>> the necessary support to activate SegWit.
>> >
>> >> The main issue is just one of activation timelines, BIP91= as
>> > is takes too long to activate unless started ahead of the exi= sting
>> > segwit2x schedule and it's unlikely that BIP148 will get = pushed back
>> > any further.
>> >
>> > Even if I'm not correct on the above, I and others find i= t hard to
>> > accept
>> > that this timeline conflict is segwit2x's fault.=C2=A0 Se= gwit2x has both some
>> > flexibility and broad support that crosses contentious pro-se= gwit and
>> > pro-blocksize-increase divisions that have existed for two ye= ars.
>> > BIP148 is
>> > attempting to hold segwit2x's timelines and code hostage = by claiming
>> > inflexibility and claiming broad support, and not only are ne= ither of
>> > those
>> > assertions are backed by real data, BIP148 (by being so infle= xible) is
>> > pushing a position that deepens the divides between those gro= ups.=C2=A0 For
>> > there
>> > to be technical reasons for compatibility (so long as there a= re
>> > tradeoffs,
>> > which there are), there needs to be hard data showing that BI= P148 is a
>> > viable minority fork that won't simply die off on its own= .
>> This is largely an issue due to segwit2x's bundling, if the SW= and HF
>> part of segwit2x were unbundled then there would be no reason to d= elay
>> BIP91 activation, this is especially a problem since it takes a go= od
>> deal of time to properly code and test a HF. Unfortunately segwit2= x
>> has been quite inflexible in regards to the bundling aspect even >> though there are clearly no technical reasons for it to be there.<= br> >> >
>> > Jared
>> >
>> >
>> > On Wed, Jun 7, 2017 at 3:23 PM, James Hilliard
>> > <james.hillia= rd1@gmail.com>
>> > wrote:
>> >>
>> >> On Wed, Jun 7, 2017 at 4:50 PM, Jared Lee Richardson
>> >> <jaredr26@gmail.= com>
>> >> wrote:
>> >> > Could this risk mitigation measure be an optional fl= ag?=C2=A0 And if so,
>> >> > could it+BIP91 signal on a different bit than bit4?<= br> >> >> It's fairly trivial for miners to signal for BIP91 on= bit4 or a
>> >> different bit at the same time as the code is trivial eno= ugh to
>> >> combine
>> >> >
>> >> > The reason being, if for some reason the segwit2x ac= tivation cannot
>> >> > take place in time, it would be preferable for miner= s to have a more
>> >> > standard approach to activation that requires strong= er consensus and
>> >> > may be more forgiving than BIP148.=C2=A0 If the segw= it2x activation is on
>> >> > time to cooperate with BIP148, it could be signaled = through the
>> >> > non-bit4 approach and everything could go smoothly.= =C2=A0 Thoughts on that
>> >> > idea?=C2=A0 It may add more complexity and more deve= loper time, but may
>> >> > also address your concerns among others.
>> >> This does give miners another approach to activate segwit= ahead of
>> >> BIP148, if segwit2x activation is rolled out and activate= d immediately
>> >> then this would not be needed however based on the timeli= ne here
>> >> https://segwit2x.github.io/ it would not be possibl= e for BIP91 to
>> >> enforce mandatory signalling ahead of BIP148. Maybe that = can be
>> >> changed though, I've suggested an immediate rollout w= ith a placeholder
>> >> client timeout instead of the HF code initially in order = to accelerate
>> >> that.
>> >> >
>> >> >> Since this BIP
>> >> >> only activates with a clear miner majority it sh= ould not increase
>> >> >> the
>> >> >> risk of an extended chain split.
>> >> >
>> >> > The concern I'm raising is more about the psycho= logy of giving BIP148
>> >> > a sense of safety that may not be valid.=C2=A0 Witho= ut several more steps,
>> >> > BIP148 is definitely on track to be a risky chainspl= it, and without
>> >> > segwit2x it will almost certainly be a small minorit= y chain. (Unless
>> >> > the segwit2x compromise falls apart before then, and= even in that
>> >> > case
>> >> > it is likely to be a minority chain)
>> >> There are 2 primary factors involved here, economic suppo= rt and
>> >> hashpower either of which is enough to make a permanent c= hain split
>> >> unlikely, miners will mine whichever chain is most profit= able(see
>> >> ETH/ETC hashpower profitability equilibrium for an exampl= e of how this
>> >> works in practice) however there may be lag time immediat= ely after the
>> >> split if there is an economic majority but not a hashpowe= r majority
>> >> initially. This is risk mitigation that only requires min= ers support
>> >> however. The main issue is just one of activation timelin= es, BIP91 as
>> >> is takes too long to activate unless started ahead of the= existing
>> >> segwit2x schedule and it's unlikely that BIP148 will = get pushed back
>> >> any further.
>> >> >
>> >> > Jared
>> >> >
>> >> >
>> >> > On Wed, Jun 7, 2017 at 2:42 PM, James Hilliard
>> >> > <jam= es.hilliard1@gmail.com> wrote:
>> >> >> I don't really see how this would increase t= he likelihood of an
>> >> >> extended chain split assuming BIP148 is going to= have
>> >> >> non-insignificant economic backing. This BIP is = designed to provide
>> >> >> a
>> >> >> risk mitigation measure that miners can safely d= eploy. Since this
>> >> >> BIP
>> >> >> only activates with a clear miner majority it sh= ould not increase
>> >> >> the
>> >> >> risk of an extended chain split. At this point i= t is not completely
>> >> >> clear how much economic support there is for BIP= 148 but support
>> >> >> certainly seems to be growing and we have nearly= 2 months until
>> >> >> BIP148
>> >> >> activation. I intentionally used a shorter activ= ation period here so
>> >> >> that decisions by miners can be made close to th= e BIP148 activation
>> >> >> date.
>> >> >>
>> >> >> On Wed, Jun 7, 2017 at 4:29 PM, Jared Lee Richar= dson
>> >> >> <jaredr= 26@gmail.com> wrote:
>> >> >>> I think this BIP represents a gamble, and th= e gamble may not be a
>> >> >>> good
>> >> >>> one.=C2=A0 The gamble here is that if the se= gwit2x changes are rolled
>> >> >>> out
>> >> >>> on time, and if the signatories accept the b= it4 + bit1 signaling
>> >> >>> proposals within BIP91, the launch will go s= moother, as intended.
>> >> >>> But
>> >> >>> conversely, if either the segwit2x signatori= es balk about the Bit1
>> >> >>> signaling OR if the timelines for segwit2mb = are missed even by a
>> >> >>> bit,
>> >> >>> it may cause the BIP148 chainsplit to be wor= se than it would be
>> >> >>> without.=C2=A0 Given the frequent concerns r= aised in multiple places
>> >> >>> about
>> >> >>> the aggressiveness of the segwit2x timelines= , including the
>> >> >>> non-hardfork timelines, this does not seem l= ike a great gamble to
>> >> >>> be
>> >> >>> making.
>> >> >>>
>> >> >>> The reason I say it may make the chainsplit = be worse than it would
>> >> >>> otherwise be is that it may provide a false = sense of safety for
>> >> >>> BIP148
>> >> >>> that currently does not currently exist(and = should not, as it is a
>> >> >>> chainsplit).=C2=A0 That sense of safety woul= d only be legitimate if the
>> >> >>> segwit2x signatories were on board, and the = segwit2x code
>> >> >>> effectively
>> >> >>> enforced BIP148 simultaneously, neither of w= hich are guaranteed.
>> >> >>> If
>> >> >>> users and more miners had a false sense that= BIP148 was *not* going
>> >> >>> to
>> >> >>> chainsplit from default / segwit2x, they mig= ht not follow the news
>> >> >>> if
>> >> >>> suddenly the segwit2x plan were delayed for = a few days.=C2=A0 While any
>> >> >>> additional support would definitely be cheer= ed on by BIP148
>> >> >>> supporters, the practical reality might be t= hat this proposal would
>> >> >>> take BIP148 from the "unlikely to have = any viable chain after flag
>> >> >>> day
>> >> >>> without segwit2x" category into the &qu= ot;small but viable minority
>> >> >>> chain"
>> >> >>> category, and even worse, it might strengthe= n the chainsplit just
>> >> >>> days
>> >> >>> before segwit is activated on BOTH chains, p= utting the BIP148
>> >> >>> supporters on the wrong pro-segwit, but stil= l-viable chain.
>> >> >>>
>> >> >>> If Core had taken a strong stance to include= BIP148 into the
>> >> >>> client,
>> >> >>> and if BIP148 support were much much broader= , I would feel
>> >> >>> differently
>> >> >>> as the gamble would be more likely to discou= rage a chainsplit (By
>> >> >>> forcing the acceleration of segwit2x) rather= than encourage it (by
>> >> >>> strengthening an extreme minority chainsplit= that may wind up on
>> >> >>> the
>> >> >>> wrong side of two segwit-activated chains).= =C2=A0 As it stands now, this
>> >> >>> seems like a very dangerous attempt to compr= omise with a small but
>> >> >>> vocal group that are the ones creating the t= hreat to begin with.
>> >> >>>
>> >> >>> Jared
>> >> >>>
>> >> >>> On Tue, Jun 6, 2017 at 5:56 PM, James Hillia= rd via bitcoin-dev
>> >> >>> <bitcoin-dev@lists.linuxfoundation.org> wrote:<= br> >> >> >>>> Due to the proposed calendar(https://s= egwit2x.github.io/) for the
>> >> >>>> SegWit2x agreement being too slow to act= ivate SegWit mandatory
>> >> >>>> signalling ahead of BIP148 using BIP91 I= would like to propose
>> >> >>>> another
>> >> >>>> option that miners can use to prevent a = chain split ahead of the
>> >> >>>> Aug
>> >> >>>> 1st BIP148 activation date.
>> >> >>>>
>> >> >>>> The splitprotection soft fork is essenti= ally BIP91 but using BIP8
>> >> >>>> instead of BIP9 with a lower activation = threshold and immediate
>> >> >>>> mandatory signalling lock-in. This allow= s for a majority of miners
>> >> >>>> to
>> >> >>>> activate mandatory SegWit signalling and= prevent a potential chain
>> >> >>>> split ahead of BIP148 activation.
>> >> >>>>
>> >> >>>> This BIP allows for miners to respond to= market forces quickly
>> >> >>>> ahead
>> >> >>>> of BIP148 activation by signalling for s= plitprotection. Any miners
>> >> >>>> already running BIP148 should be encoura= ged to use
>> >> >>>> splitprotection.
>> >> >>>>
>> >> >>>> <pre>
>> >> >>>>=C2=A0 =C2=A0BIP: splitprotection
>> >> >>>>=C2=A0 =C2=A0Layer: Consensus (soft fork)=
>> >> >>>>=C2=A0 =C2=A0Title: User Activated Soft F= ork Split Protection
>> >> >>>>=C2=A0 =C2=A0Author: James Hilliard <<= a href=3D"mailto:james.hilliard1@gmail.com">james.hilliard1@gmail.com&g= t;
>> >> >>>>=C2=A0 =C2=A0Comments-Summary: No comment= s yet.
>> >> >>>>=C2=A0 =C2=A0Comments-URI:
>> >> >>>>=C2=A0 =C2=A0Status: Draft
>> >> >>>>=C2=A0 =C2=A0Type: Standards Track
>> >> >>>>=C2=A0 =C2=A0Created: 2017-05-22
>> >> >>>>=C2=A0 =C2=A0License: BSD-3-Clause
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0= CC0-1.0
>> >> >>>> </pre>
>> >> >>>>
>> >> >>>> =3D=3DAbstract=3D=3D
>> >> >>>>
>> >> >>>> This document specifies a coordination m= echanism for a simple
>> >> >>>> majority
>> >> >>>> of miners to prevent a chain split ahead= of BIP148 activation.
>> >> >>>>
>> >> >>>> =3D=3DDefinitions=3D=3D
>> >> >>>>
>> >> >>>> "existing segwit deployment" r= efer to the BIP9 "segwit" deployment
>> >> >>>> using bit 1, between November 15th 2016 = and November 15th 2017 to
>> >> >>>> activate BIP141, BIP143 and BIP147.
>> >> >>>>
>> >> >>>> =3D=3DMotivation=3D=3D
>> >> >>>>
>> >> >>>> The biggest risk of BIP148 is an extende= d chain split, this BIP
>> >> >>>> provides a way for a simple majority of = miners to eliminate that
>> >> >>>> risk.
>> >> >>>>
>> >> >>>> This BIP provides a way for a simple maj= ority of miners to
>> >> >>>> coordinate
>> >> >>>> activation of the existing segwit deploy= ment with less than 95%
>> >> >>>> hashpower before BIP148 activation. Due = to time constraints unless
>> >> >>>> immediately deployed BIP91 will likely n= ot be able to enforce
>> >> >>>> mandatory signalling of segwit before th= e Aug 1st activation of
>> >> >>>> BIP148. This BIP provides a method for r= apid miner activation of
>> >> >>>> SegWit mandatory signalling ahead of the= BIP148 activation date.
>> >> >>>> Since
>> >> >>>> the primary goal of this BIP is to reduc= e the chance of an
>> >> >>>> extended
>> >> >>>> chain split as much as possible we activ= ate using a simple miner
>> >> >>>> majority of 65% over a 504 block interva= l rather than a higher
>> >> >>>> percentage. This BIP also allows miners = to signal their intention
>> >> >>>> to
>> >> >>>> run BIP148 in order to prevent a chain s= plit.
>> >> >>>>
>> >> >>>> =3D=3DSpecification=3D=3D
>> >> >>>>
>> >> >>>> While this BIP is active, all blocks mus= t set the nVersion header
>> >> >>>> top
>> >> >>>> 3 bits to 001 together with bit field (1= <<1) (according to the
>> >> >>>> existing segwit deployment). Blocks that= do not signal as required
>> >> >>>> will be rejected.
>> >> >>>>
>> >> >>>> =3D=3DDeployment=3D=3D
>> >> >>>>
>> >> >>>> This BIP will be deployed by "versi= on bits" with a 65%(this can be
>> >> >>>> adjusted if desired) activation threshol= d BIP9 with the name
>> >> >>>> "splitprotecion" and using bit= 2.
>> >> >>>>
>> >> >>>> This BIP starts immediately and is a BIP= 8 style soft fork since
>> >> >>>> mandatory signalling will start on midni= ght August 1st 2017 (epoch
>> >> >>>> time 1501545600) regardless of whether o= r not this BIP has reached
>> >> >>>> its
>> >> >>>> own signalling threshold. This BIP will = cease to be active when
>> >> >>>> segwit
>> >> >>>> is locked-in.
>> >> >>>>
>> >> >>>> =3D=3D=3D Reference implementation =3D= =3D=3D
>> >> >>>>
>> >> >>>> <pre>
>> >> >>>> // Check if Segregated Witness is Locked= In
>> >> >>>> bool IsWitnessLockedIn(const CBlockIndex= * pindexPrev, const
>> >> >>>> Consensus::Params& params)
>> >> >>>> {
>> >> >>>>=C2=A0 =C2=A0 =C2=A0LOCK(cs_main);
>> >> >>>>=C2=A0 =C2=A0 =C2=A0return (VersionBitsSt= ate(pindexPrev, params,
>> >> >>>> Consensus::DEPLOYMENT_SEGWIT, versionbit= scache) =3D=3D
>> >> >>>> THRESHOLD_LOCKED_IN);
>> >> >>>> }
>> >> >>>>
>> >> >>>> // SPLITPROTECTION mandatory segwit sign= alling.
>> >> >>>> if ( VersionBitsState(pindex->pp= rev, chainparams.GetConsensus(),
>> >> >>>> Consensus::DEPLOYMENT_SPLITPROTECTI= ON, versionbitscache) =3D=3D
>> >> >>>> THRESHOLD_LOCKED_IN &&
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 !IsWitnessLockedIn(p= index->pprev, chainparams.GetConsensus())
>> >> >>>> &&
>> >> >>>> // Segwit is not locked in
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 !IsWitnessEnabled(pi= ndex->pprev, chainparams.GetConsensus())
>> >> >>>> )
>> >> >>>> //
>> >> >>>> and is not active.
>> >> >>>> {
>> >> >>>>=C2=A0 =C2=A0 =C2=A0bool fVersionBits =3D= (pindex->nVersion & VERSIONBITS_TOP_MASK)
>> >> >>>> =3D=3D
>> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >>>>=C2=A0 =C2=A0 =C2=A0bool fSegbit =3D (pin= dex->nVersion &
>> >> >>>> VersionBitsMask(chainparams.GetCons= ensus(),
>> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) !=3D 0; >> >> >>>>=C2=A0 =C2=A0 =C2=A0if (!(fVersionBits &a= mp;& fSegbit)) {
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return = state.DoS(0, error("ConnectBlock(): relayed block
>> >> >>>> must
>> >> >>>> signal for segwit, please upgrade")= , REJECT_INVALID,
>> >> >>>> "bad-no-segwit");
>> >> >>>>=C2=A0 =C2=A0 =C2=A0}
>> >> >>>> }
>> >> >>>>
>> >> >>>> // BIP148 mandatory segwit signalling. >> >> >>>> int64_t nMedianTimePast =3D pindex->G= etMedianTimePast();
>> >> >>>> if ( (nMedianTimePast >=3D 1501545600= ) &&=C2=A0 // Tue 01 Aug 2017
>> >> >>>> 00:00:00
>> >> >>>> UTC
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 (nMedianTimePast <= ;=3D 1510704000) &&=C2=A0 // Wed 15 Nov 2017
>> >> >>>> 00:00:00
>> >> >>>> UTC
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 (!IsWitnessLockedIn(= pindex->pprev,
>> >> >>>> chainparams.GetConsensus())
>> >> >>>> &&
>> >> >>>>=C2=A0 // Segwit is not locked in
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 =C2=A0!IsWitnessEnab= led(pindex->pprev,
>> >> >>>> chainparams.GetConsensus())) )
>> >> >>>>=C2=A0 // and is not active.
>> >> >>>> {
>> >> >>>>=C2=A0 =C2=A0 =C2=A0bool fVersionBits =3D= (pindex->nVersion & VERSIONBITS_TOP_MASK)
>> >> >>>> =3D=3D
>> >> >>>> VERSIONBITS_TOP_BITS;
>> >> >>>>=C2=A0 =C2=A0 =C2=A0bool fSegbit =3D (pin= dex->nVersion &
>> >> >>>> VersionBitsMask(chainparams.GetCons= ensus(),
>> >> >>>> Consensus::DEPLOYMENT_SEGWIT)) !=3D 0; >> >> >>>>=C2=A0 =C2=A0 =C2=A0if (!(fVersionBits &a= mp;& fSegbit)) {
>> >> >>>>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return = state.DoS(0, error("ConnectBlock(): relayed block
>> >> >>>> must
>> >> >>>> signal for segwit, please upgrade")= , REJECT_INVALID,
>> >> >>>> "bad-no-segwit");
>> >> >>>>=C2=A0 =C2=A0 =C2=A0}
>> >> >>>> }
>> >> >>>> </pre>
>> >> >>>>
>> >> >>>>
>> >> >>>>
>> >> >>>> https://github.com/bitcoin/bitcoin/compare/0.14.= ..jameshilliard:splitprotection-v0.14.1
>> >> >>>>
>> >> >>>> =3D=3DBackwards Compatibility=3D=3D
>> >> >>>>
>> >> >>>> This deployment is compatible with the e= xisting "segwit" bit 1
>> >> >>>> deployment scheduled between midnight No= vember 15th, 2016 and
>> >> >>>> midnight
>> >> >>>> November 15th, 2017. This deployment is = also compatible with the
>> >> >>>> existing BIP148 deployment. This BIP is = compatible with BIP91 only
>> >> >>>> if
>> >> >>>> BIP91 activates before it and before BIP= 148. Miners will need to
>> >> >>>> upgrade their nodes to support splitprot= ection otherwise they may
>> >> >>>> build on top of an invalid block. While = this bip is active users
>> >> >>>> should either upgrade to splitprotection= or wait for additional
>> >> >>>> confirmations when accepting payments. >> >> >>>>
>> >> >>>> =3D=3DRationale=3D=3D
>> >> >>>>
>> >> >>>> Historically we have used IsSuperMajorit= y() to activate soft forks
>> >> >>>> such as BIP66 which has a mandatory sign= alling requirement for
>> >> >>>> miners
>> >> >>>> once activated, this ensures that miners= are aware of new rules
>> >> >>>> being
>> >> >>>> enforced. This technique can be leverage= d to lower the signalling
>> >> >>>> threshold of a soft fork while it is in = the process of being
>> >> >>>> deployed
>> >> >>>> in a backwards compatible way. We also u= se a BIP8 style timeout to
>> >> >>>> ensure that this BIP is compatible with = BIP148 and that BIP148
>> >> >>>> compatible mandatory signalling activate= s regardless of miner
>> >> >>>> signalling levels.
>> >> >>>>
>> >> >>>> By orphaning non-signalling blocks durin= g the BIP9 bit 1 "segwit"
>> >> >>>> deployment, this BIP can cause the exist= ing "segwit" deployment to
>> >> >>>> activate without needing to release a ne= w deployment. As we
>> >> >>>> approach
>> >> >>>> BIP148 activation it may be desirable fo= r a majority of miners to
>> >> >>>> have
>> >> >>>> a method that will ensure that there is = no chain split.
>> >> >>>>
>> >> >>>> =3D=3DReferences=3D=3D
>> >> >>>>
>> >> >>>>
>> >> >>>>
>> >> >>>> *[https://lists.linuxfoundation.org/pipermail/bitcoi= n-dev/2017-March/013714.html
>> >> >>>> Mailing list discussion]
>> >> >>>>
>> >> >>>>
>> >> >>>> *[https://github.com/bitcoin/bitcoin/blob/v0.6.0/src/main.c= pp#L1281-L1283
>> >> >>>> P2SH flag day activation]
>> >> >>>> *[[bip-0009.mediawiki|BIP9 Version bits = with timeout and delay]]
>> >> >>>> *[[bip-0016.mediawiki|BIP16 Pay to Scrip= t Hash]]
>> >> >>>> *[[bip-0091.mediawiki|BIP91 Reduced thre= shold Segwit MASF]]
>> >> >>>> *[[bip-0141.mediawiki|BIP141 Segregated = Witness (Consensus
>> >> >>>> layer)]]
>> >> >>>> *[[bip-0143.mediawiki|BIP143 Transaction= Signature Verification
>> >> >>>> for
>> >> >>>> Version 0 Witness Program]]
>> >> >>>> *[[bip-0147.mediawiki|BIP147 Dealing wit= h dummy stack element
>> >> >>>> malleability]]
>> >> >>>> *[[bip-0148.mediawiki|BIP148 Mandatory a= ctivation of segwit
>> >> >>>> deployment]]
>> >> >>>> *[[bip-0149.mediawiki|BIP149 Segregated = Witness (second
>> >> >>>> deployment)]]
>> >> >>>> *[https://b= itcoincore.org/en/2016/01/26/segwit-benefits/ Segwit
>> >> >>>> benefits]
>> >> >>>>
>> >> >>>> =3D=3DCopyright=3D=3D
>> >> >>>>
>> >> >>>> This document is dual licensed as BSD 3-= clause, and Creative
>> >> >>>> Commons
>> >> >>>> CC0 1.0 Universal.
>> >> >>>> ___________________________________= ____________
>> >> >>>> bitcoin-dev mailing list
>> >> >>>> bitcoin-dev@lists.linuxfoundation.org
>> >> >>>> htt= ps://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >
>> >
>
>

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