Great Consensus Cleanup Revival

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@AntoineP

It’s bad. The worst block i could come up with takes around 3 minutes to validate with all 16 cores of my modern laptop’s CPU and a hour and a half of a RPi4. For obvious reasons i’ve redacted here the details of such block, as well as the various approaches to create similarly expensive-to-validate blocks. I’ll share them in a semi-private companion post to other protocol developers using the private working group feature of Delving. If you think you should be in this working group and i forgot to add you, let me know.

• It is the worst of all the attacks described in this post and I am surprised no state sponsored miners have tried to solo mine such blocks.

• Example for one such blocks and approach is already public.

@AntoineP

Some confiscation concerns were raised about the proposed mitigations. I believe those concerns are reasonable and could be addressed by only applying the new rules when checking the script for an output created after a certain block height.

This makes sense.

@AntoineP

At this stage i’m interested in gathering as many suggestions for cleanups as i can, to make sure that if such a soft fork were to be proposed, we would have carefully analyzed all the fixes we’d like to include.

I think SIGHASH_SINGLE bug reported in 2012 should also be fixed with other bugs: [Bitcoin-development] Warning to rawtx creators: bug in SIGHASH_SINGLE