PATRON: A Pragmatic Approach for Encoding Laser Fault Injection Resistant FSMs

Abstract

Since Finite State Machines (FSMs) regulate the overall operations in majority of the digital systems, the security of an entire system can be jeopardized if the FSM is vulnerable to physical attacks. By injecting faults into an FSM, an attacker can attain unauthorized access to sensitive states, resulting in information leakage and privilege escalation. One of the powerful fault injection techniques is laser-based fault injection (LFI), which enables an adversary to alter states of individual flip-flops. While standard error correction/detection techniques have been used to protect the FSMs from such fault attacks, their significant overhead makes them unattractive to designers. To keep the overhead minimal, we propose a novel FSM encoding scheme based on decision diagrams that utilizes don t-care states of the FSM. We demonstrate that PATRON outperforms conventional encoding schemes in terms of both security and scalability for popular benchmarks. Finally, we introduce a vulnerability metric to aid the security analysis, which precisely manifests the susceptibility of FSM designs.