The HMAC algorithm is widely used to provide authentication and message integrity to digital communications. However, if the
HMAC algorithm is implemented in embedded hardware, it is vulnerable to side-channel attacks. In this paper, we describe a
DPA attack strategy for the HMAC algorithm, based on the SHA-2 hash function family. Using an implementation on a commercial
FPGA board, we show that such attacks are practical in reality. In addition, we present a masked implementation of the algorithm,
which is designed to counteract first-order DPA attacks.