A method for designing dynamical S-boxes based on discretized chaotic map

A method for obtaining dynamically cryptographically strong substitution boxes (S-boxes) based on discretized chaotic map is presented in this paper. The cryptographical properties such as bijection, nonlinearity, strict avalanche, output bits independence and equiprobable input/output XOR distribution of these S-boxes are analyzed in detail. The results of numerical analysis show that all the criteria for designing good S-box can be met approximately. As a result, our approach is suitable for practical application in designing block cryptosystem. (C) 2004 Elsevier Ltd. All rights reserved.