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From: Eric Voskuil <eric@voskuil.org>
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Subject: Re: [bitcoindev] The Tragic Tale of BIP30
Date: Sat, 10 May 2025 12:55:40 -0400
Message-Id: <197BF722-4D8F-4796-8FBC-1F002D2CCE31@voskuil.org>
References: <4AC2B1A6-23F3-4A06-808F-448D9DD58FE2@sprovoost.nl>
Cc: bitcoindev@googlegroups.com
In-Reply-To: <4AC2B1A6-23F3-4A06-808F-448D9DD58FE2@sprovoost.nl>
To: Sjors Provoost <sjors@sprovoost.nl>
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Hi Sjors,

The point I=E2=80=99m making is that introducing more complexity to try and=
 mitigate this issue, while ignoring far more likely issues resulting from =
these various hard forks, seems irrational and inconsistent. So either way =
I would close out this question.

It would make more sense to me to have the project(s) that have deployed su=
ch hard forks finally BIP all of them, as some have been deployed silently.=
 This would allow all implementations to know what the consensus might actu=
ally be (or not) without having to fish through source code repos.

At least one of these supposedly inert hard forks (silently deployed) has r=
esulted in a very likely future chain split, which the Consensus Cleanup ef=
fort is attempting to mitigate. Interestingly enough it pertains directly t=
o bip30.

At least this way various projects and their consumers can make informed de=
cisions about how they perceive the risk and the benefit. Some might simply=
 take BC at its word (that removing checkpoints is unlikely to cause a chai=
n split) and simply ignore it.

e

> On May 10, 2025, at 12:24, Sjors Provoost <sjors@sprovoost.nl> wrote:
>=20
> =EF=BB=BFHi Eric,
>=20
> I agree that deep-reorg BIP30 handling is not important. Although it _is_=
 an interesting exercise which helps to better understand consensus code. I=
 think people got distracted a bit by recent drama.
>=20
> The Bitcoin Core project "decided" many years ago to not prioritise the g=
raceful handling of extremely deep reorgs. You already stated your disagree=
ment with that approach back then. The dropping of checkpoints is a continu=
ation of that.
>=20
> The only thing that would motivate me to bring back checkpoints (i.e. und=
o the PR that dropped them) is an attack that doesn't involve alien technol=
ogy.
>=20
> At the same time I don't object to, and might even review, changes that:
>=20
> 1. are simple enough, like Solution C earlier in the thread; or
> 2. someone writes a thorough BIP that goes though all the ways different =
(versions of) implementations handle extreme reorgs, and comes up with simp=
le mitigations that make the handling consistent
>=20
> As long as they don't bring checkpoints back. I think they've outlived th=
eir usefulness as consensus training wheels and now they're just an invitat=
ion for legal attacks (or future developer laziness).
>=20
> - Sjors
>=20
>> Op 10 mei 2025, om 17:39 heeft Eric Voskuil <eric@voskuil.org> het volge=
nde geschreven:
>>=20
>> This thread seems to have gone silent. Are these pending hard forks no l=
onger interesting?
>>=20
>> e
>>=20
>>> This ignores the chain splits resulting from the 14 checkpoints that ha=
ve
>>> been removed to get to block 1. If the consensus is to not care about t=
hese
>>> hard forks causing chain splits, there is really no reason to care abou=
t
>>> this BIP30 chain split being caused by their removal.
>>>=20
>>> Best,
>>> Eric
>=20
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