Abstract

Recently the Rijndael algorithm has been uniform by the National Institute of Standards and Technology NIST as the Advanced Encryption Standard AES This makes AES a vital and necessary data-protection mechanism for federal agencies in the US and other countries In AES rotation occurs in key expansion ciphering and deciphering Rotation is vital for confusion and diffusion which play an important role in any cryptography technique Confusion and diffusion make breaking the key complex and difficult This paper studies the effect of reconfiguring the structure of AES especially replacing constant rotation with variable rotation The resulting producing another cipher is called Dynamic Rotation for Advanced Encryption Standard DRAES DRAES with variable rotation raises the complexity of the algorithm and thus increases the time consumed for brute-force attacks We measured the diffusion of AES and DRAES algorithms DRAES reached acceptable level of diffusion faster than AES