A compromise for the sake of compromise doesn't merit technical discussions. There are no benefits to be gained from a 2MB hard-fork at this time and it would impose an unnecessary cost to the ecosystem for testing and implementation.
On Fri, Mar 31, 2017 at 3:13 PM, Sergio Demian Lerner via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > > > On Fri, Mar 31, 2017 at 6:22 PM, Matt Corallo <lf-li...@mattcorallo.com> > 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. > > > I've read every proposal that was published in the last two years and the > choice for NOT implementing any of the super cool research you cite is > intentional. > > We're in a deadlock and it seems we can't go forward adding more > functionality to segwit without the community approval (which include > miners). This is obvious to me.Then we have to go back. > > If this last resort solution is merged, we could go back to discuss > improvements with the > > 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. >> >> You're are totally correct. It's a compromise for the compromise sake. I > couldn't have expressed it more clearly. However the only "riskier" element > is the hard forking date. We can move the date forward. > > >> 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. >> > > This I could consider, as it requires probably a single line of code. > Which BIP specifies this? > > >> 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. >> > > The Seghash problem has already been addressed by limiting the maximum > size of a transaction to 1 Mb. > The FindAndDelete problem has already been solved by the Core Developers, > so we don't have to worry about it anymore. > > >> c) Your really should have replay protection in any HF. > > > We could add a simple protection, although if we reach community consensus > and 95% of hashing power, does we really need to? Can the old chain still > be alive? > If more people ask for replay protection, I will merge Spoonet scheme or > develop the minimum possible replay protection (a simple signaling bit in > transaction version) > > >> 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. >> > > That is an interesting economic change and would be out of the scope of > segwit2mb. > > >> 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. >> >> That is an interesting technical improvement that is out of the scope of > segwit2mb. > We can keep discussing spoonet while we merge segwit2mb, as spoonnet > includes most of technical innovations. > > >> 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. >> >> The feedback I received is slightly different from your feedback. Many > company CTOs have expressed that one year for a Bitcoin hard-fork was > period they could schedule a secure upgrade. > > > >> 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. >> >> This is something worth considering. There is the old Pieter BIP103 > proposal has good parameters (17.7% per year). > > 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. >> >> RSK sidechain team would have to take very tough decisions if Bitcoin > splits, as RSK platform cannot be pegged to two different cryptocurrencies. > We could launch two platforms, but RSK value proposition is "supporting the > advance of Bitcoin, the cryptocurrecy with highest network effect". You > understand that if Bitcoin splits Bitcoin BTC/BTU separately may cease to > be the cryptocurrencies with higher volume/market cap/network effect. > > Therefore all RSK people that I talked too would prefer to avoid a split > at all cost, reather that to be the winners of the scaling war. > > > >> 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 > >
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