Update on the Great Consensus Cleanup Revival

The development community has been engaged in an ongoing effort to address several vulnerabilities within the Bitcoin protocol, initially sparked by Matt Corallo's 2019 Great Consensus Cleanup proposal. This proposal aimed at enhancing the security and efficiency of Bitcoin through various measures including invalidating small transactions to strengthen merkle tree integrity, refining script validation processes to mitigate block validation time concerns, and adjusting timestamp rules to prevent manipulation of difficulty adjustments.

In the months following the proposal, extensive research was conducted to understand the scope of these vulnerabilities and explore viable solutions. Key findings were shared on platforms such as Delving, with discussions extending into private forums to facilitate more detailed debates over potential fixes. These collaborative efforts underscored a commitment within the community to refine Bitcoin's protocol for better security and functionality.

The revised consensus cleanup proposal now encompasses several critical updates. It introduces mechanisms to counteract the timewarp attack by establishing a grace period for timestamp validity and addresses the Murch-Zawy attack through restrictions on difficulty adjustment periods. Moreover, to tackle the issue of prolonged block validation times, a cap on the number of legacy signature operations per transaction has been suggested. Enhancements to merkle tree security are also proposed by disallowing transactions that serialize to exactly 64 bytes. Additionally, to prevent future redundancies in BIP30 validation, changes to the nLockTime field requirements for coinbase transactions are recommended.

A draft Bitcoin Improvement Proposal (BIP) detailing these specifications is currently in progress, reflecting a comprehensive approach to fortifying the Bitcoin network against known threats. This initiative represents a significant stride towards ensuring the robustness and longevity of Bitcoin's consensus mechanism.