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From: Sjors Provoost <sjors@sprovoost.nl>
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Subject: Re: [bitcoindev] The Tragic Tale of BIP30
Date: Sat, 10 May 2025 18:17:34 +0200
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Hi Eric,

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. 

The Bitcoin Core project "decided" many years ago to not prioritise the graceful handling of extremely deep reorgs. You already stated your disagreement with that approach back then. The dropping of checkpoints is a continuation of that.

The only thing that would motivate me to bring back checkpoints (i.e. undo the PR that dropped them) is an attack that doesn't involve alien technology.

At the same time I don't object to, and might even review, changes that:

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 simple mitigations that make the handling consistent

As long as they don't bring checkpoints back. I think they've outlived their usefulness as consensus training wheels and now they're just an invitation for legal attacks (or future developer laziness).

- Sjors

> Op 10 mei 2025, om 17:39 heeft Eric Voskuil <eric@voskuil.org> het volgende geschreven:
> 
> This thread seems to have gone silent. Are these pending hard forks no longer interesting?
> 
> e
> 
>> This ignores the chain splits resulting from the 14 checkpoints that have
>> been removed to get to block 1. If the consensus is to not care about these
>> hard forks causing chain splits, there is really no reason to care about
>> this BIP30 chain split being caused by their removal.
>> 
>> Best,
>> Eric

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