Description:
Abstract AES is considered as synchronize encryption whose keys are the same in the sender and the receiver. All the researches work to enhance the security in this type of encryption by making the keys nonlinear. If attackers know any one of the sub-keys, this will lead to knowing other keys in a not difficult way. To make it more nonlinear and more difficult to be attacked, it should be more balanced between some ones and zeros in the ciphertext. We make some changes in the key expansion function to get results more balanced than the original design AES.