Edinburgh Napier University

  Complexity of an encryption algorithm is highly dependent on nonlinear components that drive actual security. Only nonlinear component in all traditional encryption algorithms is mainly Substitution Box (S-Box). In block ciphers, the relationship between plaintext amd ciphertext is abstruse via confusion operation. Due to the high sensitivity of initial conditions, utilization of chaotic equations in S-Box designing can extensively improve the security and strength of confusion operation. This paper present a novel 8 χ 8 S-Box based on the chaotic properties of Lorenz equation. In order to overcome the transient effects, initial values obtained via Lorenz equation is discarded in the proposed solution. To check the appropriateness of the proposed S-Box in image encryption scenarios, resultant encrypted image pixels from a traditional scheme are further substituted via the proposed S-Box. Standard performances indexes such as correlation coefficient, homogeneity, energy and contrast analyses have been carried out. All experimental results prove that the proposed S-Box essentially improved the security of a traditional image encryption scheme.