Construction of Improved Substitution-box With Mobius Transformation on Gf (2 8 ) and Its Application in Image Encryption

Abstract S-boxes are designed to be computationally efficient, compact and resistant to attacks, making them critical to the overall security of block ciphers. Therefore, a well-designed S-box can significantly increase the strength and robustness of block ciphers against various cryptanalytic attacks. As a result, the researchers continue to explore new and improved S-box designs to enhance the security of block ciphers. In this article the substitution matrix is assembled using the elements of Galois field of order 256 with the help of Mobius transformation. In order to increase its invulnerability an appropriate permutation is used. The proposed S-box is then used to encrypt different images after their security evaluation. At the end the results are compared with the different renowned S-boxes. AMS subject classification: Primary: 94A60; Secondary: 68P25