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

The idea discussed focuses on a cryptocurrency mechanism similar to taproot but incorporates a hash function for potentially enhanced security. This approach is suggested as an alternative that could optimize efficiency in elliptic curve (EC) spending by saving 32 bytes before the arrival of a quantum computing threat, commonly referred to as Q-day. However, this method offers quantum security only until the first transaction occurs post-Q-day. After this point, its utility diminishes unless elliptic curve spending is phased out via a soft-fork.

The concept presented here, although not entirely quantum-proof after initial use, might serve as a viable trade-off between existing protocols like P2MR and P2TRv2. It is highlighted as being conditionally safer—if no actions are taken post-Q-day—than the proposed P2TRv2, although practical challenges remain for its application once quantum capabilities become mainstream in cryptographic contexts. Such a compromise could be significant for advancing current approaches to blockchain security and efficiency, particularly in anticipating and mitigating quantum vulnerabilities.