Dynamic S-Box Design Using a Novel Square Polynomial Transformation and Permutation

New era ciphers employ substitution boxes (S-boxes) which assist in the provision of security for the plaintext in the encryption phase and transforming the ciphertext on the receiver side into original plaintext in the decryption phase. The overall security of a given cipher engaging an S-box greatly depends on the cryptographic forte of the respective S-box. Consequently, many researchers have used different innovative approaches to construct robust S-Boxes. In this article, an innovative and modest square polynomial transformation, the very first time, along with a novel affine transformation and a pioneering permutation approach to construct dynamic S-boxes is proposed. The proposed method has the capability to erect a huge number of robust S-boxes by applying minute changes in the parameters of transformation and permutation processes. An example S-Box is generated, and its recital analysis has been done using typical criteria including bijectivity, strict avalanche criterion, nonlinearity, bit independence criterion, linear probability, differential probability, and fixed-point analysis to check its cryptographic forte. This performance of the proposed S-box is placed side by side against state-of-the-art S-boxes to prove its strength. The performance and comparative analyses authenticate that the projected S-box possesses the true competence for its application in modern-day ciphers.