OTQuSbox Framework: A Quantum-Assisted Session-Based S-Box Construction With Secure Seed Synchronization

Conventional Substitution-boxes (S-boxes) used in symmetric-key cryptography are typically static or generated through deterministic pseudo-random processes, making them vulnerable to long-term structural analysis, precomputation, and learning-based cryptanalytic attacks. To address these limitations, this paper proposes OTQuSbox, a quantum-assisted session-based framework for constructing dynamic one-time 8×8 S-boxes with secure seed synchronization. The proposed model combines quantum-derived entropy with deterministic algebraic transformations inGF(28), including multiplicative inversion, primitive-element exponentiation, and affine hardening, to achieve both unpredictability and mathematical verifiability. A noisy 8-qubit quantum circuit with whitening is employed to generate high-entropy seeds, while an ephemeral Elliptic Curve Diffie–Hellman (ECDH)-based protocol enables communicating parties to securely reconstruct identical session-specific S-boxes without transmitting the S-box itself. Experimental analysis demonstrates that the generated S-boxes satisfy essential cryptographic criteria, achieving maximum nonlinearity of 108, average SAC of 0.4998, BIC nonlinearity of 103.71, differential uniformity of 10, and linear probability of 0.0625. NIST SP 800-22 randomness evaluation over 1000 trials further confirms the statistical quality of the proposed quantum seed generator. Unlike conventional static designs such as the AES S-box, OTQuSbox introduces instance-level structural diversity while preserving deterministic validation and practical efficiency, making it a promising candidate for adaptive and security-critical cryptographic applications.