We present NDP, a messaging protocol introducing Key-Derived S-box — where the substitution table is computed from session keys while preserving AES-identical cryptographic characteristics. Building upon our work on Nonna Functions, we prove that composing the AES S-box with a key-derived XOR constant preserves differential and linear properties. Experimental verification across 1000 random seeds confirms 100% stability: - Max differential probability: 4/256 (identical to AES)- Max linear bias: 16/256 (identical to AES)- Nonlinearity: 112 (identical to AES) This paper presents the conceptual framework and security analysis. Full protocol specification will follow. RELATED WORK: "Nonna Functions: An Experimental Study of Information Loss and Inversion Complexity" (DOI: 10.5281/zenodo.18361874) — theoretical foundation.
Aliaksei Naboko (Sun,) studied this question.