Secure Electronic Transaction protocol is a very large protocol in securing electronic bargains in business online for the sake of privacy. The Data Encryption Standard (DES) cons are that it is slow and short key (56 Bits). The typical attack for this one is the key exhaustion, because of the progress in the computer devices. The goal of this paper is to offer a new perspective so the protocol is more secure and fast, by using (AES) Advanced Encryption Standard (128 Bits for 10 Round , 192 Bits for 12 Round, 256 Bits for 14 Round). Besides, it has a comparison between Data Encryption Standard & Advanced Encryption Standard..