An Optimized Key Scheduling Algorithm for CAST -128 using dynamic substitution S-box

Abstract

An optimized key scheduling algorithm for the 64-bit block cipher CAST-128 by using dynamically substituting of S-box. In this regard, an attempt has been made to modify key scheduling algorithm for generating subkeys of a secret-key block cipher which is CAST-128 algorithm so as to enhance performance by modifying the generation of subkeys using dynamic substitution of S-box. The CAST-128 uses four static substitution of S-box to generate subkeys, where as the proposed structure generates subkeys using substitution of S-box dynamically to provides the performance of CAST-128. The approach considers different security aspects and metrics evaluation for verification

An improvement for CAST-128 encryption based on magic square and matrix inversion

“…The correlation coefficients of the pixels in the encrypted image can be made to have a sufficiently low correlation using an ideal encryption technique to defend against statistical attacks. The correlation coefficient can be computed using (7) [22]- [24]:…”

“…Each S-box is of size 8×32, the round number is determined by the left circular rotation operation and four operation functions [4]- [6]. The overall work of CAST 128 [7]. A magic square is used in many encryption techniques in order to increase security.…”