Abstract — With the increasing complexity of digital applications, the use of variable-length instruction sets became essential, in order to achieve higher code density and thus better performance. However, security aspects must always be considered, in particular with the significant improvement of attack techniques and equipment. Fault injection, in particular, is among the most interesting and promising attack techniques thanks to the recent advancements. In this article, we provide proper characterization, at the instruction set architecture (ISA) level, for several faulty behaviors that can be obtained when targeting a variable-length instruction set. We take into account the binary encoding of instructions, and show how the obtained behaviors depend on the alignment of the instructions in the memory. Moreover, we are also able to give a better insight on previous results from the literature, that were still partially unexplained. We also show how the observed behaviors can be exploited in various security contexts.”

Cette publication et la thèse d’Ihab s’inscrivent dans le cadre du projet CLAM (Cross-Layer Fault Analysis for Microprocessor Architectures). L’objectif de ce projet est de proposer des solutions pour évaluer très tôt dans le flot de conception les vulnérabilités matérielles afin de proposer des contre-mesures optimisées (efficaces et à faibles coûts). Ce projet qui débute sa 3ème et dernière année est financé par le labex Persyval-Lab dans le cadre de l’appel à projet “Equipe Action”. Il implique 3 laboratoires de l’UGA : Verimag, Tima et le LCIS. Le projet est réalisé aussi dans le cadre d’une collaboration avec ARM. Vincent Beroulle,  professeur Grenoble INP – UGA au LCIS est responsable de ce projet.