An Algorithm for Key-Dependent S-Box Generation in Block Cipher System

Article type: Research Article

Authors: Kazlauskas, Kazys^{; *} | Vaicekauskas, Gytis | Smaliukas, Robertas

Affiliations: Institute of Informatics and Mathematics, Vilnius University, Akademijos 4, LT-08663 Vilnius, Lithuania. E-mails: kazys.kazlauskas@mii.vu.lt, gytis.vaicekauskas@mii.vu.lt, robertas.smaliukas@mii.vu.lt

Correspondence: [*] Corresponding author.

Abstract: A nonlinear substitution operation of bytes is the main strength factor of the Advanced Encryption Standard (AES) and other modern cipher systems. In this paper we have presented a new simple algorithm to generate key-dependent S-boxes and inverse S-boxes for block cipher systems. The quality of this algorithm was tested by using NIST tests, and changing only one bit of the secret key to generate new key-dependent S-boxes. The fact that the S-boxes are key-dependent and unknown is the main strength of the algorithm, since the linear and differential cryptanalysis require known S-boxes. In the second section of the paper, we analyze S-boxes. In the third section we describe the key-dependent S-boxes and inverse S-boxes generation algorithm. Afterwards, we experimentally investigate the quality of the generated key-dependent S-boxes. Comparison results suggest that the key-dependent S-boxes have good performance and can be applied to AES.

Keywords: block cipher systems, key-dependent S-boxes, generation algorithm, experimental results

Journal: Informatica, vol. 26, no. 1, pp. 51-65, 2015