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Design of a 24 × 24 S-box over Galois Rings and its application in RGB image encryption
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DOI:10.1007/s10586-026-06464-4.png)
Abstract
En 中文
A nonlinear component in symmetric-key cryptography is a substitution box (S-box) that guarantees confusion in the block ciphers. S-boxes are conventionally designed over Galois Fields, in particular $$\:\:GF(2⁸)$$ , with $$\:8\times\:8$$ lookup tables used in many standard cryptographic designs. This paper presents a novel construction of $$\:24\times\:24$$ S-box on Galois Rings to improve the cryptographic strength for applications of RGB image encryption. For a first step, an S-box of size $$\:8\times\:8$$ using an 8 bit $$\:GF(2⁸)$$ is constructed with high nonlinearity 112. By leveraging the isomorphism between elements of Galois Field and maximal cyclic subgroups, each 8-bit element of the S-box is mapped into 24-bit element, which produces a $$\:24\times\:24$$ S-box that possesses a higher confusion capability. Then, this newly designed S-box is then merged into an RGB image encryption scheme, for which each substitution entry of 24 bit is partitioned into three bytes to accomplish R, G, and B channel confusion independently. To encrypt, it is the permutation on GF-based S-box, the substitution with Galois Ring S-box and XOR’ing. Experiments results demonstrate that the proposed method provides such significant superior security and diffusion against the traditional 8 × 8 S-box based encryption methods, which provides a solid base for high security color image encryption. The scheme is also evaluated for computational efficiency and robustness against common attacks such as noise and cropping, demonstrating its practicality for secure real-time image encryption applications.
Keywords:
Galois Ring
Maximal cyclic subgroup
S-box construction
Galois field GF(2⁸)
Confusion and diffusion
Color image encryption
Journal
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IF:
4.1
Papers:
4.8K
Citations:
7.5K
