delvingbitcoin

Great Consensus Cleanup Revival

Great Consensus Cleanup Revival

Posted on: April 5, 2024 17:34 UTC

Ensuring the uniqueness of transaction identifiers (txids) in Bitcoin is highlighted as a beneficial property, with minimal costs associated for its implementation.

A proposed rule suggests that blocks containing more than one transaction and positioned at or above the height of 1,983,702 must include a witness commitment. This stipulation provides ample time for mining software to adapt, considering it would only be enforced 21 years after the proposal, significantly beyond Bitcoin's current lifespan. The exemption of blocks solely comprising a coinbase transaction from this requirement is deemed safer due to potential custom codes employed in Simplified Payment Verification (SPV) or spy-mining activities that occur in the interval between a new block's appearance and its full validation.

The discussion extends to the rarity of pre-SegWit coinbase transactions that push the witness commitment header followed by a string of 0x00 bytes, indicating no known instances unless overlooked, as supported by a Bitcoin Stack Exchange inquiry. Moreover, it is suggested that hardcoding a check against a specific coinbase transaction ID at block 490,897 could be unnecessary. The rationale behind this is explained through the observation that even if a duplicate coinbase were to exist on an alternative blockchain fork, it would not lead to a BIP30 violation because the coinbase transaction from block 176,684 is already spent in block 185,956. Therefore, any reorganization of the blockchain would need to revert back to block 185,956, a scenario considered highly improbable due to the presence of multiple checkpoints. Despite discussions on potentially removing checkpoints as indicated in a GitHub pull request, it is acknowledged that many nodes would likely view such a deep reorganization as equivalent to a hard fork, reinforcing the system's robustness against such events.