International audienceThe secret keys manipulated by cryptographic circuits can be extracted using fault injections associated with differential cryptanalysis techniques [1]. Such faults can be induced by different means such as lasers, voltage glitches, electromagnetic perturbations or clock skews. Several counter-measures have been proposed such as random delay insertions, circuit duplications or error correcting codes. In this paper, we focus on an AES chip in which the circuit duplication principle has been implemented to detect fault injection. We show that faults based on clock set-up time violations can nevertheless be used to defeat the implemented counter-measure
