Study of a Parity Check Based Fault-Detection Countermeasure for the AES Key Schedule

In this paper we study a parity check based countermeasure proposed by Chen et al. that thwarts their attack by detecting byte fault injection during the AES key schedule process. We provide a generalization of their approach that allows to derive parity equations for every AES sizes not given by the authors. We analyze why Chen et al. countermeasure does not properly works. Doing so we are able to extend the coverage of the fault detection to the full expanded key. Finally we suggest optimizations that reduce memory and computation costs, and propose an adaptation to a more general fault model.