[bitcoin-dev] Segregated Witness in the context of Scaling Bitcoin

Mark Friedenbach mark at friedenbach.org
Thu Dec 17 09:33:26 UTC 2015

There are many reasons to support segwit beyond it being a soft-fork. For

* the limitation of non-witness data to no more than 1MB makes the
quadratic scaling costs in large transaction validation no worse than they
currently are;
* redeem scripts in witness use a more accurate cost accounting than
non-witness data (further improvements to this beyond what Pieter has
implemented are possible); and
* segwit provides features (e.g. opt-in malleability protection) which are
required by higher-level scaling solutions.

With that in mind I really don't understand the viewpoint that it would be
better to engage a strictly inferior proposal such as a simple adjustment
of the block size to 2MB.

On Thu, Dec 17, 2015 at 1:32 PM, jl2012 via bitcoin-dev <
bitcoin-dev at lists.linuxfoundation.org> wrote:

> There are at least 2 proposals on the table:
> 1. SWSF (segwit soft fork) with 1MB virtual block limit, approximately
> equals to 2MB actual limit
> 2. BIP102: 2MB actual limit
> Since the actual limits for both proposals are approximately the same, it
> is not a determining factor in this discussion
> The biggest advantage of SWSF is its softfork nature. However, its
> complexity is not comparable with any previous softforks we had. It is
> reasonable to doubt if it could be ready in 6 months
> For BIP102, although it is a hardfork, it is a very simple one and could
> be deployed with ISM in less than a month. It is even simpler than BIP34,
> 66, and 65.
> So we have a very complicated softfork vs. a very simple hardfork. The
> only reason makes BIP102 not easy is the fact that it's a hardfork.
> The major criticism for a hardfork is requiring everyone to upgrade. Is
> that really a big problem?
> First of all, hardfork is not a totally unknown territory. BIP50 was a
> hardfork. The accident happened on 13 March 2013. Bitcoind 0.8.1 was
> released on 18 March, which only gave 2 months of grace period for everyone
> to upgrade. The actual hardfork happened on 16 August. Everything completed
> in 5 months without any panic or chaos. This experience strongly suggests
> that 5 months is already safe for a simple hardfork. (in terms of
> simplicity, I believe BIP102 is even simpler than BIP50)
> Another experience is from BIP66. The 0.10.0 was released on 16 Feb 2015,
> exactly 10 months ago. I analyze the data on https://bitnodes.21.co and
> found that 4600 out of 5090 nodes (90.4%) indicate BIP66 support.
> Considering this is a softfork, I consider this as very good adoption
> already.
> With the evidence from BIP50 and BIP66, I believe a 5 months
> pre-announcement is good enough for BIP102. As the vast majority of miners
> have declared their support for a 2MB solution, the legacy 1MB fork will
> certainly be abandoned and no one will get robbed.
> My primary proposal:
> Now - 15 Jan 2016: formally consult the major miners and merchants if they
> support an one-off rise to 2MB. I consider approximately 80% of mining
> power and 80% of trading volume would be good enough
> 16 - 31 Jan 2016: release 0.11.3 with BIP102 with ISM vote requiring 80%
> of hashing power
> 1 Jun 2016: the first day a 2MB block may be allowed
> Before 31 Dec 2016: release SWSF
> My secondary proposal:
> Now: Work on SWSF in a turbo mode and have a deadline of 1 Jun 2016
> 1 Jun 2016: release SWSF
> What if the deadline is not met? Maybe pushing an urgent BIP102 if things
> become really bad.
> In any case, I hope a clear decision and road map could be made now. This
> topic has been discussed to death. We are just bringing further uncertainty
> if we keep discussing.
> Matt Corallo via bitcoin-dev 於 2015-12-16 15:50 寫到:
>> A large part of your argument is that SW will take longer to deploy
>> than a hard fork, but I completely disagree. Though I do not agree
>> with some people claiming we can deploy SW significantly faster than a
>> hard fork, once the code is ready (probably a six month affair) we can
>> get it deployed very quickly. It's true the ecosystem may take some
>> time to upgrade, but I see that as a feature, not a bug - we can build
>> up some fee pressure with an immediate release valve available for
>> people to use if they want to pay fewer fees.
>>  On the other hand, a hard fork, while simpler for the ecosystem to
>> upgrade to, is a 1-2 year affair (after the code is shipped, so at
>> least 1.5-2.5 from today if we all put off heads down and work). One
>> thing that has concerned me greatly through this whole debate is how
>> quickly people seem to think we can roll out a hard fork. Go look at
>> the distribution of node versions on the network today and work
>> backwards to get nearly every node upgraded... Even with a year
>> between fork-version-release and fork-activation, we'd still kill a
>> bunch of nodes and instead of reducing their security model, lead them
>> to be outright robbed.
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