Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 4831E72A for ; Sat, 1 Apr 2017 11:44:55 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-qk0-f181.google.com (mail-qk0-f181.google.com [209.85.220.181]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 86C1410C for ; Sat, 1 Apr 2017 11:44:52 +0000 (UTC) Received: by mail-qk0-f181.google.com with SMTP id d201so55653241qkc.0 for ; Sat, 01 Apr 2017 04:44:52 -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; bh=yC8QrOo0wz+b94Lt/BAlzUOvtDCirQQXodqC0l7LpsA=; b=H+f1ObzOx4OpbUiQo7EKtEH6kNsSesR/EsWTCPHSObVlNf+0jiwzK4iiIc0nHXh7rI disgkPXfTtHp0H+g1MMrEsSMn+95cHWUbLyw2qgcKcneRV8QZvPW81USnO/UV0sNPtTP xk6dqqPnXd+Qol0xtuwK81Pc62YXZSAT67JuFnC9XJklgF+OlvMT6iL/Sug0cKoeU2Iz IPxx4T+uruaKDYjy1wdJ07hSfuIhOZ0Kja9UWdXCdG15KQSzON0kaeC7sl4AVoIjtBaT HjPL4cj5hhZyKbVScGmXBmVyS7ZM2ENCWUQ9ijhsi5eq4wSUm95I9dPxNcLbkilwZ6QS 5UFg== 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; bh=yC8QrOo0wz+b94Lt/BAlzUOvtDCirQQXodqC0l7LpsA=; b=W0izeGysZptkk5zBjHpwkCE5FsSFwbN10diolQSePgFph4pPXGVhYoROVNe+kqKBSJ ce/KmkF9pU5SdFmjgTtmt46FOo4CHxuNZhad2BATbSKHVrMsZIiu3I9CcEvCWaje/J3j 7xZjUX4aKQLFL6v7sMnUNrLAQ/WKFUtH9ZTTQerv2DJIKRwoGd+RzER/eFTwoN1Lw7tp MkC4WTFvVruU82f+TWTZfsUlqGELFeOQge0XqYX9K07mCLZf4UzyG4QgsXuajdpbvlmz jBrEoZNwZugy1ubRl1JYkEsK6DcOA6SMk7ADJy2dkiNAkmw/LNMmlkIedLryAFuZt6/Z FuIQ== X-Gm-Message-State: AFeK/H242BvoKMUxcNAGbjlv6TYYAm8E3n8z/xcxYUoISJfrogOFBzp80JMekGhNAeMIvfHEfb/28seamZAe6A== X-Received: by 10.55.161.200 with SMTP id k191mr7854726qke.265.1491047091561; Sat, 01 Apr 2017 04:44:51 -0700 (PDT) MIME-Version: 1.0 Received: by 10.12.170.220 with HTTP; Sat, 1 Apr 2017 04:44:11 -0700 (PDT) In-Reply-To: References: <1CF1FD5D-8D29-4783-823F-B3F588D5C5CE@mattcorallo.com> From: Sergio Demian Lerner Date: Sat, 1 Apr 2017 08:44:11 -0300 Message-ID: To: Bitcoin Protocol Discussion Content-Type: multipart/alternative; boundary=94eb2c06f3403c8408054c1974b6 X-Spam-Status: No, score=-1.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_NONE, RCVD_IN_SORBS_SPAM 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] Segwit2Mb - combined soft/hard fork - Request For Comments 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: Sat, 01 Apr 2017 11:44:55 -0000 --94eb2c06f3403c8408054c1974b6 Content-Type: text/plain; charset=UTF-8 Some people have asked me for the current implementation of this patch to review. I remind you that the current patch does not implement the hard-fork signaling, as requested by Matt. The Segwit2Mb patch can be found here: https://github.com/SergioDemianLerner/bitcoin/commits/master For now, the segwit2mb repo has a single test file using the old internal blockchain building method (test/block_size_tests.cpp). This must be replaced soon with a better external test using the bitcoin/qa/rpc-tests tests, which I will begin to work on now after I collect all comments from the community. regards On Sat, Apr 1, 2017 at 3:55 AM, Jared Lee Richardson wrote: > > Remember that the "hashpower required to secure bitcoin" is determined > > as a percentage of total Bitcoins transacted on-chain in each block > > Can you explain this statement a little better? What do you mean by > that? What does the total bitcoins transacted have to do with > hashpower required? > > On Fri, Mar 31, 2017 at 2:22 PM, Matt Corallo via bitcoin-dev > wrote: > > Hey Sergio, > > > > You appear to have ignored the last two years of Bitcoin hardfork > > research and understanding, recycling instead BIP 102 from 2015. There > > are many proposals which have pushed the state of hard fork research > > much further since then, and you may wish to read some of the posts on > > this mailing list listed at https://bitcoinhardforkresearch.github.io/ > > and make further edits based on what you learn. Your goal of "avoid > > technical changes" appears to not have any basis outside of perceived > > compromise for compromise sake, only making such a hardfork riskier > > instead. > > > > At a minimum, in terms of pure technical changes, you should probably > > consider (probably among others): > > > > a) Utilizing the "hard fork signaling bit" in the nVersion of the block. > > b) Either limiting non-SegWit transactions in some way to fix the n**2 > > sighash and FindAndDelete runtime and memory usage issues or fix them by > > utilizing the new sighash type which many wallets and projects have > > already implemented for SegWit in the spending of non-SegWit outputs. > > c) Your really should have replay protection in any HF. The clever fix > from > > Spoonnet for poor scaling of optionally allowing non-SegWit outputs to > > be spent with SegWit's sighash provides this all in one go. > > d) You may wish to consider the possibility of tweaking the witness > > discount and possibly discounting other parts of the input - SegWit went > > a long ways towards making removal of elements from the UTXO set cheaper > > than adding them, but didn't quite get there, you should probably finish > > that job. This also provides additional tuneable parameters to allow you > > to increase the block size while not having a blowup in the worst-case > > block size. > > e) Additional commitments at the top of the merkle root - both for > > SegWit transactions and as additional space for merged mining and other > > commitments which we may wish to add in the future, this should likely > > be implemented an "additional header" ala Johnson Lau's Spoonnet > proposal. > > > > Additionally, I think your parameters here pose very significant risk to > > the Bitcoin ecosystem broadly. > > > > a) Activating a hard fork with less than 18/24 months (and even then...) > > from a fully-audited and supported release of full node software to > > activation date poses significant risks to many large software projects > > and users. I've repeatedly received feedback from various folks that a > > year or more is likely required in any hard fork to limit this risk, and > > limited pushback on that given the large increase which SegWit provides > > itself buying a ton of time. > > > > b) Having a significant discontinuity in block size increase only serves > > to confuse and mislead users and businesses, forcing them to rapidly > > adapt to a Bitcoin which changed overnight both by hardforking, and by > > fees changing suddenly. Instead, having the hard fork activate technical > > changes, and then slowly increasing the block size over the following > > several years keeps things nice and continuous and also keeps us from > > having to revisit ye old blocksize debate again six months after > activation. > > > > c) You should likely consider the effect of the many technological > > innovations coming down the pipe in the coming months. Technologies like > > Lightning, TumbleBit, and even your own RootStock could significantly > > reduce fee pressure as transactions move to much faster and more > > featureful systems. > > > > Commitments to aggressive hard fork parameters now may leave miners > > without much revenue as far out as the next halving (which current > > transaction growth trends are indicating we'd just only barely reach 2MB > > of transaction volume, let alone if you consider the effects of users > > moving to systems which provide more features for Bitcoin transactions). > > This could lead to a precipitous drop in hashrate as miners are no > > longer sufficiently compensated. > > > > Remember that the "hashpower required to secure bitcoin" is determined > > as a percentage of total Bitcoins transacted on-chain in each block, so > > as subsidy goes down, miners need to be paid with fees, not just price > > increases. Even if we were OK with hashpower going down compared to the > > value it is securing, betting the security of Bitcoin on its price > > rising exponentially to match decreasing subsidy does not strike me as a > > particularly inspiring tradeoff. > > > > There aren't many great technical solutions to some of these issues, as > > far as I'm aware, but it's something that needs to be incredibly > > carefully considered before betting the continued security of Bitcoin on > > exponential on-chain growth, something which we have historically never > > seen. > > > > Matt > > > > > > On March 31, 2017 5:09:18 PM EDT, Sergio Demian Lerner via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > >>Hi everyone, > >> > >>Segwit2Mb is the project to merge into Bitcoin a minimal patch that > >>aims to > >>untangle the current conflict between different political positions > >>regarding segwit activation vs. an increase of the on-chain blockchain > >>space through a standard block size increase. It is not a new solution, > >>but > >>it should be seen more as a least common denominator. > >> > >>Segwit2Mb combines segwit as it is today in Bitcoin 0.14+ with a 2MB > >>block > >>size hard-fork activated ONLY if segwit activates (95% of miners > >>signaling), but at a fixed future date. > >> > >>The sole objective of this proposal is to re-unite the Bitcoin > >>community > >>and avoid a cryptocurrency split. Segwit2Mb does not aim to be best > >>possible technical solution to solve Bitcoin technical limitations. > >>However, this proposal does not imply a compromise to the future > >>scalability or decentralization of Bitcoin, as a small increase in > >>block > >>size has been proven by several core and non-core developers not to > >>affect > >>Bitcoin value propositions. > >> > >>In the worst case, a 2X block size increase has much lower economic > >>impact > >>than the last bitcoin halving (<10%), which succeeded without problem. > >> > >>On the other side, Segwit2Mb primary goal is to be minimalistic: in > >>this > >>patch some choices have been made to reduce the number of lines > >>modified in > >>the current Bitcoin Core state (master branch), instead of implementing > >>the > >>most elegant solution. This is because I want to reduce the time it > >>takes > >>for core programmers and reviewers to check the correctness of the > >>code, > >>and to report and correct bugs. > >> > >>The patch was built by forking the master branch of Bitcoin Core, > >>mixing a > >>few lines of code from Jeff Garzik's BIP102, and defining a second > >>versionbits activation bit (bit 2) for the combined activation. > >> > >>The combined activation of segwit and 2Mb hard-fork nVersion bit is 2 > >>(DEPLOYMENT_SEGWIT_AND_2MB_BLOCKS). > >> > >>This means that segwit can still be activated without the 2MB hard-fork > >>by > >>signaling bit 1 in nVersion (DEPLOYMENT_SEGWIT). > >> > >>The tentative lock-in and hard-fork dates are the following: > >> > >>Bit 2 signaling StartTime = 1493424000; // April 29th, 2017 > >> > >>Bit 2 signaling Timeout = 1503964800; // August 29th, 2017 > >> > >>HardForkTime = 1513209600; // Thu, 14 Dec 2017 00:00:00 GMT > >> > >> > >>The hard-fork is conditional to 95% of the hashing power has approved > >>the > >>segwit2mb soft-fork and the segwit soft-fork has been activated (which > >>should occur 2016 blocks after its lock-in time) > >> > >>For more information on how soft-forks are signaled and activated, see > >>https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki > >> > >>This means that segwit would be activated before 2Mb: this is > >>inevitable, > >>as versionbits have been designed to have fixed activation periods and > >>thresholds for all bits. Making segwit and 2Mb fork activate together > >>at a > >>delayed date would have required a major re-write of this code, which > >>would > >>contradict the premise of creating a minimalistic patch. However, once > >>segwit is activated, the hard-fork is unavoidable. > >> > >>Although I have coded a first version of the segwit2mb patch (which > >>modifies 120 lines of code, and adds 220 lines of testing code), I > >>would > >>prefer to wait to publish the source code until more comments have been > >>received from the community. > >> > >>To prevent worsening block verification time because of the O(N^2) > >>hashing > >>problem, the simple restriction that transactions cannot be larger than > >>1Mb > >>has been kept. Therefore the worse-case of block verification time has > >>only > >>doubled. > >> > >>Regarding the hard-fork activation date, I want to give enough time to > >>all > >>active economic nodes to upgrade. As of Fri Mar 31 2017, > >>https://bitnodes.21.co/nodes/ reports that 6332 out of 6955 nodes (91%) > >>have upgraded to post 0.12 versions. Upgrade to post 0.12 versions can > >>be > >>used to identify economic active nodes, because in the 0.12 release > >>dynamic > >>fees were introduced, and currently no Bitcoin automatic payment system > >>can > >>operate without automatic discovery of the current fee rate. A pre-0.12 > >>would require constant manual intervention. > >>Therefore I conclude that no more than 91% of the network nodes > >>reported by > >>bitnodes are active economic nodes. > >> > >>As Bitcoin Core 0.12 was released on February 2016, the time for this > >>91% > >>to upgrade has been around one year (under a moderate pressure of > >>operational problems with unconfirmed transactions). > >>Therefore we can expect a similar or lower time to upgrade for a > >>hard-fork, > >>after developers have discussed and approved the patch, and it has been > >>reviewed and merged and 95% of the hashing power has signaled for it > >>(the > >>pressure not to upgrade being a complete halt of the operations). > >>However I > >>suggest that we discuss the hard-fork date and delay it if there is a > >>real > >>need to. > >> > >>Currently time works against the Bitcoin community, and so is delaying > >>a > >>compromise solution. Most of the community agree that halting the > >>innovation for several years is a very bad option. > >> > >>After the comments collected by the community, a BIP will be written > >>describing the resulting proposal details. > >> > >>If segwit2mb locks-in, before hard-fork occurs all bitcoin nodes should > >>be > >>updated to a Segwit2Mb enabled node to prevent them to be forked-away > >>in a > >>chain with almost no hashing-power. > >> > >>The proof of concept patch was made for Bitcoin Core but should be > >>easily > >>ported to other Bitcoin protocol implementations that already support > >>versionbits. Lightweight (SPV) wallets should not be affected as they > >>generally do not check the block size. > >> > >>I personally want to see the Lightning Network in action this year, use > >>the > >>non-malleability features in segwit, see the community discussing other > >>exciting soft-forks in the scaling roadmap, Schnorr sigs, drivechains > >>and > >>MAST. > >> > >>I want to see miners, developers and industry side-by-side pushing > >>Bitcoin > >>forward, to increase the value of Bitcoin and prevent high transaction > >>fees > >>to put out of business use-cases that could have high positive social > >>impact. > >> > >>I believe in the strength of a unified Bitcoin community. If you're a > >>developer, please give your opinion, suggest changes, audit it, and > >>take a > >>stand with me to unlock the current Bitcoin deadlock. > >> > >>Contributions to the segwit2mb project are welcomed and awaited. The > >>only > >>limitation is to stick to the principle that the patch should be as > >>simple > >>to audit as possible. As an example, I wouldn't feel confident if the > >>patch > >>modified more than ~150 lines of code. > >> > >>Improvements unrelated to a 2 Mb increase or segwit, as beneficial as > >>it > >>may be to Bitcoin, should not be part of segwit2Mb. > >> > >>This proposal should not prevent other consensus proposals to be > >>simultaneously merged: segwit2mb is a last resort solution in case we > >>can > >>not reach consensus on anything better. > >> > >>Again, the proposal is only a starting point: community feedback is > >>expected and welcomed. > >> > >>Regards, > >>Sergio Demian Lerner > > _______________________________________________ > > bitcoin-dev mailing list > > bitcoin-dev@lists.linuxfoundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > --94eb2c06f3403c8408054c1974b6 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Some people have asked me for the current implementation o= f this patch to review. I remind you that the current patch does not implem= ent the hard-fork signaling, as requested by Matt.


For now, the segwit2mb repo has a single test file using the= old internal blockchain building method (test/block_size_tests.cpp). This = must be replaced soon with a better external test using the bitcoin/qa/rpc-= tests tests, which I will begin to work on now after I collect all comments= from the community.


=

<= span style=3D"vertical-align:baseline">regards



O= n Sat, Apr 1, 2017 at 3:55 AM, Jared Lee Richardson <<= a href=3D"mailto:jaredr26@gmail.com" target=3D"_blank">jaredr26@gmail.com> wrote:
>= ; Remember that the "hashpower required to secure bitcoin" is det= ermined
> as a percentage of total Bitcoins transacted on-chain in each block
Can you explain this statement a little better?=C2=A0 What do you me= an by
that?=C2=A0 What does the total bitcoins transacted have to do with
hashpower required?

On Fri, Mar 31, 2017 at 2:22 PM, Matt Corallo via bitcoin-dev
<bitcoin-dev@li= sts.linuxfoundation.org> wrote:
> Hey Sergio,
>
> You appear to have ignored the last two years of Bitcoin hardfork
> research and understanding, recycling instead BIP 102 from 2015. There=
> are many proposals which have pushed the state of hard fork research > much further since then, and you may wish to read some of the posts on=
> this mailing list listed at https://bitcoinhardf= orkresearch.github.io/
> and make further edits based on what you learn. Your goal of "avo= id
> technical changes" appears to not have any basis outside of perce= ived
> compromise for compromise sake, only making such a hardfork riskier > instead.
>
> At a minimum, in terms of pure technical changes, you should probably<= br> > consider (probably among others):
>
> a) Utilizing the "hard fork signaling bit" in the nVersion o= f the block.
> b) Either limiting non-SegWit transactions in some way to fix the n**2=
> sighash and FindAndDelete runtime and memory usage issues or fix them = by
> utilizing the new sighash type which many wallets and projects have > already implemented for SegWit in the spending of non-SegWit outputs.<= br> > c) Your really should have replay protection in any HF. The clever fix= from
> Spoonnet for poor scaling of optionally allowing non-SegWit outputs to=
> be spent with SegWit's sighash provides this all in one go.
> d) You may wish to consider the possibility of tweaking the witness > discount and possibly discounting other parts of the input - SegWit we= nt
> a long ways towards making removal of elements from the UTXO set cheap= er
> than adding them, but didn't quite get there, you should probably = finish
> that job. This also provides additional tuneable parameters to allow y= ou
> to increase the block size while not having a blowup in the worst-case=
> block size.
> e) Additional commitments at the top of the merkle root - both for
> SegWit transactions and as additional space for merged mining and othe= r
> commitments which we may wish to add in the future, this should likely=
> be implemented an "additional header" ala Johnson Lau's = Spoonnet proposal.
>
> Additionally, I think your parameters here pose very significant risk = to
> the Bitcoin ecosystem broadly.
>
> a) Activating a hard fork with less than 18/24 months (and even then..= .)
> from a fully-audited and supported release of full node software to > activation date poses significant risks to many large software project= s
> and users. I've repeatedly received feedback from various folks th= at a
> year or more is likely required in any hard fork to limit this risk, a= nd
> limited pushback on that given the large increase which SegWit provide= s
> itself buying a ton of time.
>
> b) Having a significant discontinuity in block size increase only serv= es
> to confuse and mislead users and businesses, forcing them to rapidly > adapt to a Bitcoin which changed overnight both by hardforking, and by=
> fees changing suddenly. Instead, having the hard fork activate technic= al
> changes, and then slowly increasing the block size over the following<= br> > several years keeps things nice and continuous and also keeps us from<= br> > having to revisit ye old blocksize debate again six months after activ= ation.
>
> c) You should likely consider the effect of the many technological
> innovations coming down the pipe in the coming months. Technologies li= ke
> Lightning, TumbleBit, and even your own RootStock could significantly<= br> > reduce fee pressure as transactions move to much faster and more
> featureful systems.
>
> Commitments to aggressive hard fork parameters now may leave miners > without much revenue as far out as the next halving (which current
> transaction growth trends are indicating we'd just only barely rea= ch 2MB
> of transaction volume, let alone if you consider the effects of users<= br> > moving to systems which provide more features for Bitcoin transactions= ).
> This could lead to a precipitous drop in hashrate as miners are no
> longer sufficiently compensated.
>
> Remember that the "hashpower required to secure bitcoin" is = determined
> as a percentage of total Bitcoins transacted on-chain in each block, s= o
> as subsidy goes down, miners need to be paid with fees, not just price=
> increases. Even if we were OK with hashpower going down compared to th= e
> value it is securing, betting the security of Bitcoin on its price
> rising exponentially to match decreasing subsidy does not strike me as= a
> particularly inspiring tradeoff.
>
> There aren't many great technical solutions to some of these issue= s, as
> far as I'm aware, but it's something that needs to be incredib= ly
> carefully considered before betting the continued security of Bitcoin = on
> exponential on-chain growth, something which we have historically neve= r
> seen.
>
> Matt
>
>
> On March 31, 2017 5:09:18 PM EDT, Sergio Demian Lerner via bitcoin-dev= <bitcoin-dev@l= ists.linuxfoundation.org> wrote:
>>Hi everyone,
>>
>>Segwit2Mb is the project to merge into Bitcoin a minimal patch that=
>>aims to
>>untangle the current conflict between different political positions=
>>regarding segwit activation vs. an increase of the on-chain blockch= ain
>>space through a standard block size increase. It is not a new solut= ion,
>>but
>>it should be seen more as a least common denominator.
>>
>>Segwit2Mb combines segwit as it is today in Bitcoin 0.14+ with a 2M= B
>>block
>>size hard-fork activated ONLY if segwit activates (95% of miners >>signaling), but at a fixed future date.
>>
>>The sole objective of this proposal is to re-unite the Bitcoin
>>community
>>and avoid a cryptocurrency split. Segwit2Mb does not aim to be best=
>>possible technical solution to solve Bitcoin technical limitations.=
>>However, this proposal does not imply a compromise to the future >>scalability or decentralization of Bitcoin, as a small increase in<= br> >>block
>>size has been proven by several core and non-core developers not to=
>>affect
>>Bitcoin value propositions.
>>
>>In the worst case, a 2X block size increase has much lower economic=
>>impact
>>than the last bitcoin halving (<10%), which succeeded without pr= oblem.
>>
>>On the other side, Segwit2Mb primary goal is to be minimalistic: in=
>>this
>>patch some choices have been made to reduce the number of lines
>>modified in
>>the current Bitcoin Core state (master branch), instead of implemen= ting
>>the
>>most elegant solution. This is because I want to reduce the time it=
>>takes
>>for core programmers and reviewers to check the correctness of the<= br> >>code,
>>and to report and correct bugs.
>>
>>The patch was built by forking the master branch of Bitcoin Core, >>mixing a
>>few lines of code from Jeff Garzik's BIP102,=C2=A0 and defining= a second
>>versionbits activation bit (bit 2) for the combined activation.
>>
>>The combined activation of segwit and 2Mb hard-fork nVersion bit is= 2
>>(DEPLOYMENT_SEGWIT_AND_2MB_BLOCKS).
>>
>>This means that segwit can still be activated without the 2MB hard-= fork
>>by
>>signaling bit 1 in nVersion=C2=A0 (DEPLOYMENT_SEGWIT).
>>
>>The tentative lock-in and hard-fork dates are the following:
>>
>>Bit 2 signaling StartTime =3D 1493424000; // April 29th, 2017
>>
>>Bit 2 signaling Timeout =3D 1503964800; // August 29th, 2017
>>
>>HardForkTime =3D 1513209600; // Thu, 14 Dec 2017 00:00:00 GMT
>>
>>
>>The hard-fork is conditional to 95% of the hashing power has approv= ed
>>the
>>segwit2mb soft-fork and the segwit soft-fork has been activated (wh= ich
>>should occur 2016 blocks after its lock-in time)
>>
>>For more information on how soft-forks are signaled and activated, = see
>>https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki
>>
>>This means that segwit would be activated before 2Mb: this is
>>inevitable,
>>as versionbits have been designed to have fixed activation periods = and
>>thresholds for all bits. Making segwit and 2Mb fork activate togeth= er
>>at a
>>delayed date would have required a major re-write of this code, whi= ch
>>would
>>contradict the premise of creating a minimalistic patch. However, o= nce
>>segwit is activated, the hard-fork is unavoidable.
>>
>>Although I have coded a first version of the segwit2mb patch (which=
>>modifies 120 lines of code, and adds 220 lines of testing code), I<= br> >>would
>>prefer to wait to publish the source code until more comments have = been
>>received from the community.
>>
>>To prevent worsening block verification time because of the O(N^2)<= br> >>hashing
>>problem, the simple restriction that transactions cannot be larger = than
>>1Mb
>>has been kept. Therefore the worse-case of block verification time = has
>>only
>>doubled.
>>
>>Regarding the hard-fork activation date, I want to give enough time= to
>>all
>>active economic nodes to upgrade. As of Fri Mar 31 2017,
>>https://bitnodes.21.co/nodes/ reports that 6332 out of= 6955 nodes (91%)
>>have upgraded to post 0.12 versions. Upgrade to post 0.12 versions = can
>>be
>>used to identify economic active nodes, because in the 0.12 release=
>>dynamic
>>fees were introduced, and currently no Bitcoin automatic payment sy= stem
>>can
>>operate without automatic discovery of the current fee rate. A pre-= 0.12
>>would require constant manual intervention.
>>Therefore I conclude that no more than 91% of the network nodes
>>reported by
>>bitnodes are active economic nodes.
>>
>>As Bitcoin Core 0.12 was released on February 2016, the time for th= is
>>91%
>>to upgrade has been around one year (under a moderate pressure of >>operational problems with unconfirmed transactions).
>>Therefore we can expect a similar or lower time to upgrade for a >>hard-fork,
>>after developers have discussed and approved the patch, and it has = been
>>reviewed and merged and 95% of the hashing power has signaled for i= t
>>(the
>>pressure not to upgrade being a complete halt of the operations). >>However I
>>suggest that we discuss the hard-fork date and delay it if there is= a
>>real
>>need to.
>>
>>Currently time works against the Bitcoin community, and so is delay= ing
>>a
>>compromise solution. Most of the community agree that halting the >>innovation for several years is a very bad option.
>>
>>After the comments collected by the community, a BIP will be writte= n
>>describing the resulting proposal details.
>>
>>If segwit2mb locks-in, before hard-fork occurs all bitcoin nodes sh= ould
>>be
>>updated to a Segwit2Mb enabled node to prevent them to be forked-aw= ay
>>in a
>>chain with almost no hashing-power.
>>
>>The proof of concept patch was made for Bitcoin Core but should be<= br> >>easily
>>ported to other Bitcoin protocol implementations that already suppo= rt
>>versionbits. Lightweight (SPV) wallets should not be affected as th= ey
>>generally do not check the block size.
>>
>>I personally want to see the Lightning Network in action this year,= use
>>the
>>non-malleability features in segwit, see the community discussing o= ther
>>exciting soft-forks in the scaling roadmap, Schnorr sigs, drivechai= ns
>>and
>>MAST.
>>
>>I want to see miners, developers and industry side-by-side pushing<= br> >>Bitcoin
>>forward, to increase the value of Bitcoin and prevent high transact= ion
>>fees
>>to put out of business use-cases that could have high positive soci= al
>>impact.
>>
>>I believe in the strength of a unified Bitcoin community. If you= 9;re a
>>developer, please give your opinion, suggest changes, audit it, and=
>>take a
>>stand with me to unlock the current Bitcoin deadlock.
>>
>>Contributions to the segwit2mb project are welcomed and awaited. Th= e
>>only
>>limitation is to stick to the principle that the patch should be as=
>>simple
>>to audit as possible. As an example, I wouldn't feel confident = if the
>>patch
>>modified more than ~150 lines of code.
>>
>>Improvements unrelated to a 2 Mb increase or segwit, as beneficial = as
>>it
>>may be to Bitcoin, should not be part of segwit2Mb.
>>
>>This proposal should not prevent other consensus proposals to be >>simultaneously merged: segwit2mb is a last resort solution in case = we
>>can
>>not reach consensus on anything better.
>>
>>Again, the proposal is only a starting point: community feedback is=
>>expected and welcomed.
>>
>>Regards,
>>Sergio Demian Lerner
> __________________= _____________________________
> bitcoin-dev mailing list
> bitcoin-dev@l= ists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev

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