Subject: [Bitcoin-development] comments on BIP 100

From: Adam Back <[email-masked]>
Date: Sun, 14 Jun 2015 23:23:55 +0200

Hi

I made these comments elsewhere, but I think really we should be
having these kind of conversations here rather than scattered around.

These are about Jeff Garzik's outline draft BIP 100 I guess this is
the latest draft:  (One good thing about getting off SF would be
finally JGarzik's emails actually not getting blocked!).

http://gtf.org/garzik/bitcoin/BIP100-blocksizechangeproposal.pdf

may have changed since the original [1]

Over the original proposal:

1. there should be a hard cap, not indefinitely growing.

2. there should be  a growth limiter (no more than X%/year)

3. I think the miners should not be given a vote that has no costs to
cast, because their interests are not necessarily aligned with users
or businesses.

I think Greg Maxwell's difficulty adjust [2] is better here for that
reason.  It puts quadratic cost via higher difficulty for miners to
vote to increase block-size, which miners can profitably do if there
are transactions with fees available to justify it. There is also the
growth limiter as part of Greg's proposal. [3]

I think bitcoin will have to involve layering models that uplift
security to higher layers, but preserve security assurances, and
smart-contracts even, with protocols that improve the algorithmic
complexity beyond O(n^2) in users, like lightning, and there are
multiple other candidates with useful tradeoffs for various use-cases.

One thing that is concerning is that few in industry seem inclined to
take any development initiatives or even integrate a library.  I
suppose eventually that problem would self-correct as new startups
would make a more scalable wallet and services that are layer2 aware
and eat the lunch of the laggards.  But it will be helpful if we
expose companies to the back-pressure actually implied by an O(n^2)
scaling protocol and don't just immediately increase the block-size to
levels that are dangerous for decentralisation security, as an
interventionist subsidy to save them having to do basic integration
work.  Otherwise I think whichever any kind of kick the can some 2-5
years down the road we consider, we risk the whole saga repeating in a
few years, when no algorithmic progress has been made and even more
protocol inertia has set in.

Adam

[1] original proposal comments on reddit
https://www.reddit.com/r/Bitcoin/comments/39kzyt/draft_bip_100_soft_fork_block_size_increase/

[2] flexcap propoal by Greg Maxwell see post by Mark Freidenbach
https://www.mail-archive.com/[email-masked]/msg07599.html

[3] growth limited proposal for flexcap by Greg Maxwell
https://www.mail-archive.com/[email-masked]/msg07620.html