This paper describes a novel approach for implementation of the advanced encryption standard (AES) algorithm, which provides a significantly improved strength against first-order differential electromagnetic and power analysis with a minimal additional overhead. Our method is based on randomization in composite field arithmetic, which entails a low implementation cost while does not alter the algorithm, does not reduce the working frequency, and keeps perfect compatibility with the published standard. The efficiency of the proposed technique was verified by practical results obtained from real implementation on an AT89C51AC2 microcontroller.
Another contribution of this paper is that it describes experimental setup and the measurement probe, i.e., the critical piece of equipment for performing electromagnetic analysis attacks. Most of the probes that are used for electromagnetic attacks in the published papers are self-made and no detailed specification is available for them. The results of this paper can be served for protecting some microprocessor-based security tokens with limited resources such as smart cards.