S*FSM: A Paradigm Shift for Attack Resistant FSM Designs and Encodings

Abstract

While hardware design focuses on creating minimally-sized circuits, this paper proposes that security-centric designs require a departure from this mentality. The need for built-in protection mechanisms at all levels of design is paramount to providing cost-effective secure systems. We focus on the high-level design of sequential circuits by targeting Finite State Machines (FSMs) and their vulnerability to non-invasive, side channel based, attacks. The unconventional paradigm shift needed is justified by showing that conventional, minimalism-based, FSM synthesis and encodings allow direct correlation between state/transitions and Hamming Models. A two-fold method, involving structural modifications and specific encoding strategies, is proposed for side-channel secure FSM (S*FSMs). Preliminary high-level simulations show the effectiveness and potential for security driven S*FSM synthesis methods to mitigate the relationship between attack models and underlying hardware implementations.