From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id B4D67DA1 for ; Mon, 14 Dec 2015 12:32:05 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mout.perfora.net (mout.perfora.net [74.208.4.197]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 7914811D for ; Mon, 14 Dec 2015 12:32:03 +0000 (UTC) Received: from mail-io0-f178.google.com ([209.85.223.178]) by mrelay.perfora.net (mreueus001) with ESMTPSA (Nemesis) id 0MWRTQ-1ZjjM82Cks-00Xn9G for ; Mon, 14 Dec 2015 13:32:02 +0100 Received: by ioae126 with SMTP id e126so41532744ioa.1 for ; Mon, 14 Dec 2015 04:32:01 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.107.167.9 with SMTP id q9mr29438203ioe.84.1450096321873; Mon, 14 Dec 2015 04:32:01 -0800 (PST) Received: by 10.36.49.200 with HTTP; Mon, 14 Dec 2015 04:32:01 -0800 (PST) Date: Mon, 14 Dec 2015 20:32:01 +0800 X-Gmail-Original-Message-ID: Message-ID: From: Adam Back To: Jonathan Toomim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K0:PFVMDbq8HlQ+BfEYQ27SftzsawhOmz4zSziBxoay+6y4mQMJR0J pL5RQMB+Mz00GbMLFaEG5JMoEGTFjNUOFONLWvY11+RfHKV9Eoz2bqdrns2lG627u6YXzXL pOK803DchfThWzyalnThgro7vJraRFoRbPsJs+w0ogndpUrezVEupECFzg5JxfiAitep1nL SKupkkFIZF32LRulL0SPQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:dVD72ulK3Hg=:oxOoZdvpg6Ry5ab0TjAr7F 1aeMYjCQASI/bSR4K8Gx+jmM8xwVYD6DYOw/6Dq1Dm3pkL6DucWQQGPa05qk94nS92Jmpm42H mWEEB+WP2+fvXnlyOZm/F/p+CKbCySxS1cUaXZG47QK0+01KCJ6DzUGrlB+FMNtauUyX+LYWF GgurlLuWdQC5S8BUlGvzKet3yWDIvUB5CMDAH81TEe8ZtJt0GyNR7RkQMItEcfx8hkoF1mz/c h1tM8gLCW+HYWq7kEzYZXIR1DEG5kd/6ELBoAYCST34WOxquPpfXi3CyV7DkFwqIZ47toBJJI bw2uTFzdlTyED4IZhqmvykeKR6KswFxX2/kMWS6TWrchDK2acL0Tcc+sKGQlQdAd902CqE2O1 uEvqFkcruUeQQssRAg17bic3w/yQUXchY94R17H9qD/1l6ygFzJWVxEzk6KfZjEsRicFGrig4 +KxdIKnK+BZDepwp8aUowQaitKka1fFYE67mP3q8KGyZ9gpsM/IoWpd+3RpXPYyDLPfsETZqG uLXmlo418I8Q91+tXnlvQzRC2t4/7vdCSqUN68R4KOP/rXP0LosM9w4hHgix3dCqQRrWXX6B4 72S45AqpDzGlzGP6FvZpJuwyYC18OZ5D+vRfPUWGcr8xAPRld7kHHd3eHfwTFZimSR0wf8BGU e1N4O0bOrtAbfCeSS+pV8pfGgMMa7bhuOPaiherQ3Jgigf4cgPGjkZyik25+bsSQQcetIWEL3 BrZ9R1OcGCi8H0PM X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] Segregated Witness features wish list X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 14 Dec 2015 12:32:05 -0000 I think people have a variety of sequences in mind, eg some would prefer to deploy versionBits first, so that subsequent features can be deployed in parallel (currently soft-fork deployment is necessarily serialised). Others think do seg-witness first because scale is more important. Some want to do seg-witness as a hard-fork (personally I think that would take a bit longer to deploy & activate - the advantage of soft-fork is that it's lower risk and we have more experience of it). I've seen a few people want to do BIP 102 first (straight move to 2MB and only that) and then do seg-witness and other scaling work later. That's possible also and before Luke observed that you could do a seg-witness based block-size increase via soft-fork, people had been working following the summary from the montreal workshop discussion posted on this list about a loose plan of action, people had been working on something like BIP 102 to 2-4-8 kind of space, plus validation cost accounting. So I think personally soft-fork seg-witness first, but hey I'm not writing code at present and I'm very happy for wiser and more code and deployment detail aware minds to figure out the best deployment strategy, I wouldnt mind any of the above, just think seg-witness soft-fork is the safest and fastest. The complexity risk - well on the plus side it is implemented and it reduces deployment risk, and it's anyway needed work to have a robust malleability fix which is needed for a whole range of bitcoin smart-contract, and scaling features, including for example greenAddress like faster transactions as used by BitPay?, BitGo and GreenAddress as well as lightning related proposals and basically any smart-contract use that involves multiple clauses and dependent transactions. Also re complexity risk Greg has highlighted that the complexity and overhead difference is really minor. About knock on code changes needed, a bunch of the next steps for Bitcoin are going to need code changes, I think our scope to improve and scale Bitcoin are going to be severely hampered if we restricted ourselves with the pre-condition that we cant make protocol improvements. I think people in core would be happy to, and have done this kind of thing multiple times in the past, to help people for free on volunteer time integrate and fix up related code in various languages and FOSS and commercial software that is affected. As to time-line Luke I saw guestimated by march 2016 on reddit. Others maybe be more or less conservative. Probably a BIP and testing are the main thing, and that can be helped by more eyes. The one advantage of BIP 102 like proposal is simplicity if one had to do a more emergency hard-fork. Maybe companies and power users, miners and pool operators could help define some requirements and metrics about an industry wide service level they are receiving relative to fees. The other thing which is not protocol related, is that companies can help themselves and help Bitcoin developers help them, by working to improve decentralisation with better configurations, more use of self-hosted and secured full nodes, and decentralisation of policy control over hashrate. That might even include buying a nominal (to a reasonably funded startup) amount of mining equipment. Or for power users to do more of that. Some developers are doing mining. Blockstream and some employees have a little bit of hashrate. If we could define some metrics and best practices and measure the improvements, that would maybe reduce miners concerns about centralisation risk and allow a bigger block faster, alongside the IBLT & weak block network protocol improvements. Adam On 14 December 2015 at 19:44, Jonathan Toomim via bitcoin-dev wrote: > 1. I think we should limit the sum of the block and witness data to nBloc= kMaxSize*7/4 per block, for a maximum of 1.75 MB total. I don't like the id= ea that SegWit would give us 1.75 MB of capacity in the typical case, but w= e have to have hardware capable of 4 MB in adversarial conditions (i.e. int= entional multisig). I think a limit to the segwit size allays that concern. > > 2. I think that segwit is a substantial change to how Bitcoin works, and = I very strongly believe that we should not rush this. It changes the block = structure, it changes the transaction structure, it changes the network pro= tocol, it changes SPV wallet software, it changes block explorers, and it h= as changes that affect most other parts of the Bitcoin ecosystem. After we = decide to implement it, and have a final version of the code that will be m= erged, we should give developers of other Bitcoin software time to implemen= t code that supports the new transaction/witness formats. > > When you guys say "as soon as possible," what do you mean exactly? > > On Dec 10, 2015, at 2:47 PM, jl2012--- via bitcoin-dev wrote: > >> It seems the current consensus is to implement Segregated Witness. SW op= ens many new possibilities but we need a balance between new features and d= eployment time frame. I'm listing by my priority: >> >> 1-2 are about scalability and have highest priority >> >> 1. Witness size limit: with SW we should allow a bigger overall block si= ze. It seems 2MB is considered to be safe for many people. However, the exa= ct size and growth of block size should be determined based on testing and = reasonable projection. >> >> 2. Deployment time frame: I prefer as soon as possible, even if none of = the following new features are implemented. This is not only a technical is= sue but also a response to the community which has been waiting for a scali= ng solution for years