P2QRH / BIP-360 Update

In the discussion surrounding the implementation of quantum-resistant signature schemes within Bitcoin's framework, particularly in an emergency scenario, a simplified approach is advocated. The focus is on utilizing straightforward security assumptions by primarily incorporating hash-based signatures, with a spotlight on SPHINCS+ for their integration. This method suggests embedding these signatures within a taproot leaf to maintain simplicity and effectiveness without drastically altering the existing infrastructure.

The compatibility with BIP 32 is mentioned as not critically important for this "emergency break glass" setup, implying that most wallets, which are already configured with a root key, could adapt by embedding the post-quantum public key (PQ pubkey) into all of their outputs. This strategy acknowledges a potential privacy compromise; however, it is deemed acceptable in such emergency circumstances, underlining the expectation that any provisional measures would be superseded by more sophisticated solutions as further knowledge and technology evolve.

Furthermore, the conversation touches upon the necessity of implementing this feature through an opcode to facilitate multisig capabilities, illustrating an intention to preserve Bitcoin's multifunctional and secure environment even while introducing new, quantum-resistant elements. This dialogue reflects a proactive stance on enhancing Bitcoin's resilience to quantum computing threats, emphasizing pragmatic steps that can be taken without overhauling the system’s foundational principles.