Public key recovery for EC leaves in P2MR (BIP-360)

The ongoing debate in cryptocurrency security focuses on the adoption of different protocols for wallet types, considering the implications post-Quantum (Q-day) disruption. For high-value storage managed responsibly, P2MR protocol is identified as a preferable choice due to its ability to maintain cost-effective pre-Q-day EC spending and secure transactions on Q-day before the disabling of EC (Elliptic Curve cryptography). This contrasts with other protocols such as P2QR, which lacks these benefits.

For regular wallets, the decision narrows down to choosing between P2TRv2 and P2TRH protocols. P2TRH offers a significant security advantage since it protects against theft by CRQC (Cryptographically Relevant Quantum Computing) if the EC public key remains undisclosed. This ensures that at least some assets remain safe post-Q-day depending on user behavior. In contrast, P2TRv2 exposes user assets to vulnerabilities immediately after Q-day and before any EC-disabling measures take effect, making it less secure during this critical transition period.

However, P2TRv2 holds benefits in simplicity, its adherence to existing BIP-340 verification standards, batch validation capabilities, direct-pubkey constructions, and a clearer security model. These features make it attractive despite its security lapses in the face of quantum computing threats. On the downside, the anticipated migration from P2TRv2 to P2MR on Q-day could potentially cause a significant increase in mempool fees due to the sudden spike in transaction volume. This scenario underlines the need for strategic planning in cryptographic protocol selection and management, especially as the advent of quantum computing looms closer.