Dynamic generation of s-boxes in block cipher systems

Block cipher systems are widely used in cryptographic applications. The main problem in implementing any block cipher system is the fixed structure of s-boxes elements. In this paper we present a new method to build up dynamic look-up tables (s-boxes) changing with every change of the secret key in addition to an evaluation criterion of block ciphers. This new approach leads to more secure block cipher systems and consequently solves the problem of the fixed structure block ciphers.