Changes to BIP-360 - Pay to Quantum Resistant Hash (P2QRH)

A significant modification includes transitioning from Pay to Quantum Resistant Hash (P2QRH) to a script-only version of Taproot (P2TR), thereby removing pathways vulnerable to quantum attacks. This change ensures that P2QRH outputs are directly committed to the tapleaf merkle root, enhancing security. The scriptPubKey for P2QRH outputs has been adjusted to OP_PUSHNUM_3 OP_PUSHBYTES_32, reflecting these updates and leveraging existing taproot infrastructure for easier integration and familiarity among users. This modification not only simplifies the implementation but also boosts protection against long-exposure attacks, which are likely to be feasible before short-exposure ones. It provides an alternative to disabling key-spends in P2TR on Q-Day when quantum attacks might become viable, giving the ecosystem time to adapt without the pressure of imminent threats.

Additionally, the proposal outlines a forward-looking plan concerning Post-Quantum (PQ) signatures, decoupling their specification from BIP-360 to allow for independent consideration and development. This strategic separation facilitates ongoing progress on P2QRH while avoiding premature commitments to specific PQ signature algorithms. An informational section within BIP-360 suggests incorporating tapscript PQ signature verification opcodes for ML-DSA (CRYSTALS-Dilithium) and SLH-DSA (SPHINCS+) through OP_SUCCESSx opcodes. This proposed method offers a flexible framework for activating PQ signature algorithms separately if desired and establishes a blueprint for integrating new signature algorithms in the future without necessitating new tapleaf versions. A comprehensive specification for these PQ signatures is expected to be detailed in an upcoming BIP, further contributing to the robustness and quantum resistance of the Bitcoin protocol.

In terms of naming conventions, there is advocacy for a shift to better reflect the multi-faceted utility of the features beyond just their quantum resistance capabilities. Suggestions include renaming the proposed soft-fork from p2qrh to either pay-to-tapscript (p2ts) or pay-to-mast, emphasizing the broader applicability and demand across different segments of the ecosystem. The suggested name, P2QRH, explicitly signals quantum resistance, distinguishing it from other output types like P2TR, which could be susceptible to quantum attacks. Further elaboration on naming strategies highlights the use of Segwit version 3, intentionally incorporating an 'r' to signify resistance (e.g., bc1r.). This mnemonic device is designed to aid users in easily remembering and identifying quantum-resistant addresses. The goal is to prevent users from mistakenly sending funds to potentially vulnerable addresses (denoted with bc1p.), thereby mitigating the risk of losses due to quantum computing advancements.

Lastly, a programmer humorously admits to having previously taken unconventional steps just to secure acknowledgment or approval (referred to as an ACK) for their BIPs. This candid admission reveals a lighter side of the process involved in proposing and discussing improvements within the Bitcoin ecosystem, suggesting that beyond the technical rigors, interpersonal dynamics and creative persuasion play a role. The individual is considering making a formal proposal request (PR) based on this naming convention, indicating a proactive step towards innovation in the space. Moreover, a link to GitHub details specific alterations made by the sender (here's what it looks like), highlighting collaborative efforts and consensus building among contributors in the Bitcoin community.