Secure and Efficient AES Software Implementation for Smart Cards

In implementing cryptographic algorithms on limited devices such as smart cards, speed and memory optimization had always been a challenge. With the advent of side channel attacks, this task became even more difficult because a programmer must take into account countermeasures against such attacks, which often increases computational time, or memory requirements, or both. In this paper we describe a new method for secure implementation of the Advanced Encryption Standard algorithm. The method is based on a data masking technique, which is the most widely used countermeasure against power analysis and timing attacks at a software level. The change of element representation allows us to achieve an efficient solution that combines low memory requirements with high speed and resistance to attacks.