Re: [bitcoin-dev] Trinary Version Signaling for softfork upgrades

From: Eric Voskuil <eric@voskuil•org>
To: Luke Dashjr <luke@dashjr•org>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists•linuxfoundation.org>
Cc: Billy Tetrud <billy.tetrud@gmail•com>
Subject: Re: [bitcoin-dev] Trinary Version Signaling for softfork upgrades
Date: Sat, 26 Jun 2021 14:43:55 -0700	[thread overview]
Message-ID: <CB5A45C6-6446-4ECE-AD7D-8F079F8661BF@voskuil.org> (raw)
In-Reply-To: <202106262113.05006.luke@dashjr.org>

For some definitions of “block”.

Without majority hash power support, activation simply means you are off on a chain split. Anyone can of course split off from a chain by changing a rule (soft or otherwise) at any time, so this is a bit of an empty claim.

Nobody can stop a person from splitting. The relevant question is how to *prevent* a split. And activation without majority hash power certainly does not “ensure” this.

e

> On Jun 26, 2021, at 14:13, Luke Dashjr via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote:
> 
> BIP8 LOT=True just ensures miners cannot block an upgrade entirely. They can 
> still slow it down.
> 
> It also already has the trinary state you seem to be describing (although 
> perhaps this could be better documented in the BIP): users who oppose the 
> softfork can and should treat the successful signal (whether MASF or UASF) as 
> invalid, thereby ensuring they do not follow a chain with the rules in force.
> 
> No additional bit is needed, as softforks are coordinated between users, NOT 
> miners (who have no particular say in them, aside from their role as also 
> being users). The miner involvement is only out of necessity (to set the bit 
> in the header, which users coordinate with) and potentially to accelerate 
> activation by protecting upgrade-lagging users.
> 
> Luke
> 
> 
>> On Saturday 26 June 2021 20:21:52 Billy Tetrud via bitcoin-dev wrote:
>> Given the recent controversy over upgrade mechanisms for the
>> non-controversial taproot upgrade, I have been thinking about ways to solve
>> the problems that both sides brought up. In short, BIP8 LOT=true proponents
>> make the point that lazy miners failing to upgrade in a timely manner slow
>> down releases of bitcoin upgrades, and BIP9 / BIP8 LOT=false
>> proponents make the point that LOT=true can lead to undesirable forks that
>> might cause a lot of chaos. I believe both points are essentially correct
>> and have created a proposal
>> <https://github.com/fresheneesz/bip-trinary-version-signaling/blob/master/b
>> ip-trinary-version-bits.md> for soft fork upgrades that solve both problems.
>> 
>> The proposal uses trinary version signaling rather than binary signaling.
>> For any particular prospective soft fork upgrade, this allows for three
>> signaling states:
>> 
>> * Actively support the change.
>> * Actively oppose the change.
>> * Not signaling (neither support or oppose). This is the default state.
>> 
>> Using this additional information, we can release non-contentious upgrades
>> much quicker (with a much lower percent of miners signaling support). For
>> contentious upgrades, miners who oppose the change are incentivized to
>> update their software to a version that can actively signal opposition to
>> the change. The more opposition there is, the higher the threshold
>> necessary to lock in the upgrade. With the parameters I currently
>> recommended in the proposal, this chart shows how much support signaling
>> would be necessary given a particular amount of active opposition
>> signaling:
>> 
>> [image: thresholdChart.png]
>> If literally no one signals opposition, a 60% threshold should be
>> relatively safe because it is a supermajority amount that is unlikely to
>> change significantly very quickly (ie if 60% of miners support the change
>> today, its unlikely that less than a majority of miners would support the
>> change a year or two from now), and if no one is signaling opposition,
>> chances are that the vast majority of the other 40% would also eventually
>> signal support.
>> 
>> This both gives an incentive for "lazy" miners to upgrade if they actually
>> oppose the change while at the same time allowing these lazy miners to
>> remain lazy without slowing down the soft fork activation much.
>> 
>> I think now is the right time to discuss new soft fork upgrade mechanisms,
>> when there are no pressing soft fork upgrades ready to deploy. Waiting
>> until we need to deploy a soft fork to discuss this will only delay things
>> and cause contention again like it did with taproot.
>> 
>> I'm very curious to know what people think of this mechanism. I would
>> appreciate any comments here, or written as github issues on the proposal
>> repo itself.
>> 
>> Thanks,
>> BT
> 
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