Tori, Meaad Asad N

Paul, David John

Billingsley, William

2025-04-22

<p>This thesis addresses the challenge of discovering and designing critical components within lightweight cryptographic primitives to enhance security against advanced cryptographic attacks. Emphasising the significant role of S-Boxes in symmetric cryptography, the research investigates optimised design and integration strategies to elevate both security and efficiency within constrained environments. Through a detailed examination of cryptographic systems, cryptanalysis strategies, and studying many lightweight cryptographic algorithms, this work lays a foundation for understanding the needs to enhance the security and efficiency in lightweight cryptographic environments. </p><p>The core investigation focuses on utilising evolutionary algorithms, specifically memetic and genetic search algorithms, to discover and optimise Substitution Boxes (S-Boxes). To validate our approach, we replicated a study that introduced the concept of "Golden S-Boxes", which exhibit superior properties essential for robust cryptographic functions. This thesis demonstrates how these evolutionary algorithms navigate extensive search spaces to discover S-Boxes that meet stringent security requirements with efficient performance which can then be integrated into lightweight cryptographic systems. Our approach successfully replicated the discovery of 4x4 Golden S-Boxes, and we enhance the algorithm to support all S-Box sizes. </p><p>Our code provides specific properties selected to find candidate S-Boxes that balance between security considerations and suitability for use in lightweight environments. While our code currently considers only linear equivalent S-Boxes, it can be updated to include other variations. Additionally, our code is open-source, allowing for further customisation and improvement by the community. Although we do not offer customisable properties based on size, the code can be adjusted to generate S-Boxes of any size, and users can add or omit properties and fine-tune parameters as needed. For instance, we present a 5x5 candidate S-Box, similar in size and properties to the one used in the ASCON cryptographic standard. </p><p>The approach in this research apply both the theory and practice of lightweight cryptographic methods. The methods developed offer a scalable way to enhance cryptographic strength, showing clear improvements in security and efficiency for modern applications, particularly in lightweight environments.</p>

https://hdl.handle.net/1959.11/69840

en

University of New England

Discovery and Analysis of Lightweight S-Boxes Using Memetic Algorithms

Thesis Doctoral

Publication