Simple Setup for SPHINCS+ Bitcoin-style Address (proof-of-concept)

The exploration of using post-quantum cryptographic methods to generate Bitcoin-style addresses has led to the development of a proof-of-concept utilizing SPHINCS+ with the double-shake256 algorithm. This approach eschews traditional elliptic curve techniques, opting instead for a quantum-resistant method that could be viable in a post-quantum computing (PQC) era. The process involves two programs where the first, referred to as prog1, uses a 32-byte seed to produce a 105-byte slice from a SPHINCS+ signature. Subsequently, the second program, prog2, condenses this slice into a 20-byte payload through SHAKE256-based methods.

Prog2 is designed to generate two types of addresses. The first type adheres to the standard Bitcoin address format which includes double-SHA256 hashing and Base58Check encoding. The second type modifies the checksum to use double-SHAKE256 while retaining the same Base58 format. This indicates a potential hybrid approach that may be beneficial prior to a significant PQC update. Additionally, a simple role-based derivation system is incorporated, allowing for the generation of derived keys from a master key by incrementing the role value.

The entire setup is minimalistic, intentionally using small parameters and the official SPHINCS+ reference code to demonstrate feasibility. The premise suggests that, following a major PQC fork, it would be straightforward to adjust these parameters back to their standard levels with minimal changes required to the existing pipeline. This flexibility highlights a potential pathway for transitioning Bitcoin into a quantum-resistant future without relying on elliptic curve cryptography.

For those interested in further details or contributing to the development of this concept, the repository containing this proof of concept can be found here. This initiative is currently open for discussion and feedback within the Bitcoin development community, aiming to refine and potentially implement this new methodology in anticipation of evolving cryptographic challenges.