Artuğer, Fırat

Cryptography aims to design algorithms for the protection of important data transmitted over unsecured networks. These algorithms encrypt the data and render it incomprehensible even if it is captured by enemies. Today’s data encryption standard is the AES algorithm. The most important and nonlinear unit in the AES algorithm is the s-box structure. The S-box provides the mixing process in the algorithm, that is, the confusion. An s-box structure with a high nonlinearity value greatly increases the security against various attacks. Therefore, s-box is of vital importance in an encryption algorithm. When we look at the literature, chaos-based s-box structures are frequently used. However, the nonlinearity value of s-boxes produced with chaos is low. In this article, a new, fast, and very simple method is proposed to increase the nonlinearity value of chaos-based s-box structures. In the proposed method, the nonlinearity value is calculated by changing the places of the elements respectively. When the nonlinearity value increases, the s-box is updated, and the next element is passed. In this way, many iterations are not looked at in vain. This saves a lot of time. As a result of the analysis, it has been proven that the s-box structure obtained by the proposed method is cryptographically strong and has a high nonlinearity value. It is thought that the proposed method will provide many advantages for future cryptography applications.

AtıfScopus9·WoS7·OpenAlex8

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Artuğer, Fırat

Encryption provides security in cases such as storing confidential information or transmitting it over a network. Today, block cipher algorithms are generally used for encryption. Undoubtedly, one of the most important units of block cipher algorithms to ensure confidentiality is substitution box (s-box) structures. Because s-boxes are nonlinear structures, making the algorithm resistant to differential cryptanalysis. Therefore, the higher the nonlinearity value of the s-box, the stronger it will be. In this study, a new algorithm is proposed to generate s-boxes with high nonlinearity value. In the proposed algorithm, Lorenz and Chua systems, which are 3D chaotic maps, are used for the initial population. The s-boxes produced with these chaotic maps were then increased to 110.5 using the whale optimization algorithm (WOA). WOA is one of the important optimization algorithms developed in recent years and was used for the first time in s-box production in this study. Looking at the results of the analysis, the proposed method has outstripped most of the other existing studies, thanks to effective 3D chaotic maps and WOA.

AtıfScopus44·WoS38·OpenAlex45

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