Proposing a P2QRH BIP towards a quantum resistant soft fork

The discussion highlights the comparison between SPHINCS+ and SQIsign, underscoring the maturity and development of SPHINCS+ as it enters its third round with standards-compliant implementations and a detailed specification available, unlike SQIsign which is still primarily documented through research papers. The size of NIST-I round 3 signatures for SPHINCS+ is notably 982 bytes, a detail found in documents available on the SPHINCS website (SPHINCS+ Documentation). To accommodate this difference in signature sizes without requiring specific operations like OP_CAT, the suggestion involves introducing SPHINCS+ as a distinct address type from SQIsign. This approach aims to limit the scope of the proposed soft fork, while also provisionally supporting an increase in the witness discount should SQIsign encounter significant vulnerabilities in the future.

Furthermore, there are mentions of additional modifications made in response to feedback received on another matter, X, with those changes being accessible for review at a GitHub repository (Review Changes). This demonstrates an ongoing process of refinement and community engagement in the development work.