A Chaotic Map-Based S-Box Design Reinforced by Secretary Bird Optimization Algorithm for Securing IoT Systems

Abstract

In the Internet of Things (IoT), there is a growing need for robust and lightweight substitution boxes (S-boxes) that can provide strong cryptographic resistance, with nonlinearity and differential uniformity serving as the most critical and attack-relevant metrics, while being efficiently generated on resource-constrained devices without specialized hardware. The core challenge lies in developing S-boxes that simultaneously meet these conflicting requirements. This study addresses this trilemma by introducing the Secretary Bird Optimization Algorithm (SBOA), a bioinspired framework that integrates chaotic initialization with specialized local (stomping) and global (kicking) search strategies, enhanced by self-adaptive parameter control. To the best of our knowledge, this marks the first application of SBOA in the context of cryptographic design for securing IoT system. Evaluated against state-of-the-art methods, SBOA achieves record-breaking nonlinearity (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{NL}=116$</tex>), competitive differential uniformity (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{DU}=10$</tex>), and significantly faster execution (2.92 seconds) in pure software environments, outperforming even GPU- or FPGA-accelerated alternatives. Its ability to deliver strong cryptographic properties with real-time efficiency represents a significant advancement for lightweight security in resource-constrained IoT environments.