Hi Antoine,

First off, concept ACK. My concerns are procedural rather than objections
to the individual security fixes themselves.

The "Great Consensus Cleanup" is a fantastic brand for communicating these
protocol changes to non-technical users. However, since this is a technical
forum and we are producing BIPs intended for technical audiences, I believe
we should document these changes in separate BIPs.

The proposed security fixes are largely unrelated from a technical
standpoint:

   1.

   Timewarp attack mitigation
   2.

   Worst-case block validation constraints
   3.

   Disallowing 64-byte transactions
   4.

   Avoiding duplicate transactions

We should absolutely retain the "Great Consensus Cleanup" branding while
independently documenting each security enhancement.

A common concern I’ve heard about splitting this BIP is that deploying soft
forks is difficult, so all changes should be bundled together. While soft
fork deployment is indeed challenging, we've successfully activated
multiple BIPs within a single soft fork in the past—e.g., BIP141 and BIP143
in Segwit, as well as BIP341, BIP342, and BIP343 in Taproot. If the
community reaches consensus, we can still deploy all these changes
together, even if they are documented separately.

This approach also provides flexibility: if one of the proposed changes
turns out to be controversial, we could remove it without holding up the
rest of the improvements. Additionally, once these fixes are deployed,
there will likely be significant research and documentation to incorporate,
and maintaining independent BIPs will make it easier to manage that growth.

I do see merit in implementing all the security fixes in a single PR for
Bitcoin Core. More active contributors to the project may have stronger
opinions on the best approach there.

-Chris
------------------------------




On Wed, Mar 26, 2025 at 1:23 PM 'Antoine Poinsot' via Bitcoin Development
Mailing List <bitcoindev@googlegroups.com> wrote:

> Hi everyone,
>
> About two months ago i shared an update on this list about my (and
> others', really) work on the
> Consensus Cleanup [0]. I am now ready to share a BIP draft for a Consensus
> Cleanup soft fork.
>
> The BIP draft can be found here:
> https://github.com/darosior/bips/blob/consensus_cleanup/bip-cc.md
>
> It includes the following fixes:
> - a restriction on the timestamp of the first and last blocks of a
> difficulty adjustment period to
>   address the Timewarp and Murch-Zawy attacks;
> - a limit on the number of legacy signature operations that may be
> executed in validating a single
>   transaction to address long block validation times;
> - making 64 bytes transactions invalid to address weaknesses in the block
> Merkle tree construction;
> - mandating coinbase transactions be timelocked to their block height to
> prevent future transaction
>   duplication without resorting to BIP30 validation.
>
> This BIP draws on the 2019 Great Consensus Cleanup proposal from Matt
> Corallo [1]. A number of
> people contributed ideas, testing, data or useful discussions. This
> includes Ava Chow, Matt Corallo,
> Mark Erhardt, Brian Groll, David A. Harding, Sjors Provoost, Anthony
> Towns, Greg Sanders, Chris
> Stewart, Eric Voskuil, @0xb10c and others.
>
> Antoine Poinsot
>
> [0]
> https://gnusha.org/pi/bitcoindev/jiyMlvTX8BnG71f75SqChQZxyhZDQ65kldcugeIDJVJsvK4hadCO3GT46xFc7_cUlWdmOCG0B_WIz0HAO5ZugqYTuX5qxnNLRBn3MopuATI=@protonmail.com
> [1]
> https://github.com/TheBlueMatt/bips/blob/7f9670b643b7c943a0cc6d2197d3eabe661050c2/bip-XXXX.mediawiki
>
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> .
>

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