Technical Report TR-2K1-9, LCIS, National Central University, Taiwan, R.O.C., May 3, 2001.

Abstract.   In this article, we demonstrate that a modified implementation of the Rijndael cipher against timing cryptanalysis is however vulnerable to the differential power cryptanalysis (DPA).  Analysis shows that the proposed attack on Rijndael is very powerful and feasible when compared with other reported DPA on other symmetric key cryptosystems. This article clearly shows that a countermeasure developed against one physical attack may still provide a side-channel for another physical attack.