A developed cryptographic model based on AES cryptosystem.

AES as a block cipher considers as one of the most important security applications that provides confidentiality through encryption. However, AES cryptosystem is under analyzing by cryptanalysts using the computing technologies that have rapidly progressed. Therefore, the possibility of breaking AES algorithm might be accelerated in anytime. Consequently, this paper improves the AES security against a possible future attack. It proposes a model that has the ability to encrypt data with block size 256-bit and a key size of 256-bits. In addition, it also uses S-box of the serpent algorithm to be replaced the original S-box of the AES cryptosystem. The implementation of the proposed idea shows that the time requirements is acceptable even if the shifting algorithm is applied in two directions on row and column. Moreover, the randomness of the modified algorithm remains high. [ABSTRACT FROM AUTHOR]