Spinel: A Post-Quantum Signature Scheme Based on SLn(Fp) Hashing

Spinel is a post-quantum digital signature scheme that combines the security of SPHINCS+ with a new family of algebraic hash functions based on the Tillich-Zemor paradigm over SL_n(F_p). The scheme's security relies on the hardness of navigating expander graphs over SL_n(F_p), which is believed to be resistant to quantum adversaries. The work includes empirical security evidence, integration within the SPHINCS+ framework, security analysis, parameter selection, and performance evaluation demonstrating practical feasibility.