Towards mixed structural-functional models for algebraic fault attacks on ciphers

Fault attacks are a major threat for hardware-implemented security primitives, and algebraic techniques (equation-solving) are one of the most powerful building blocks for such attacks. We show that structural models obtained from a circuit implementation of the analyzed cipher can lead to more efficient attacks than the functional models used in literature. We also discuss possible synergies of the traditional functional and the proposed structural models and show first results on mixed models that combine structural and functional information. The overspecification provided by the mixed models creates an optimization potential through a partial mixed model with different filter rules for the combination of the two models.