Prohibit Merkle Internal Node Preimages That Encode Minimal 64-Byte Transactions

In the recent discourse on the Bitcoin Development Mailing List, an alternative mitigation strategy against certain attacks was proposed. However, this strategy suggests that miners would need to modify their block-building software to manage potentially malicious transaction selections that could lead them to create invalid blocks. This requirement is a significant drawback because it involves changing existing deployed software, which is not ideal for soft forks. The preservation of current miner operations, especially those with custom block-building logic, remains a critical objective in the design and implementation of soft forks.

Furthermore, the discussion highlighted that 64-byte transactions, which have been non-standard for a long time, do not appear to be used currently. As such, there seems little risk associated with banning these types of transactions. This ban could potentially serve as a more comprehensive solution to the problem at hand. According to contributions from several participants in the mailing list, eliminating 64-byte transactions from acceptance in blocks might avoid the complications associated with altering miner software while effectively mitigating the identified vulnerabilities.