A State Encoding Methodology for Side-Channel Security vs. Power Trade-off Exploration

Abstract

Power side-channel attacks have been shown to be effective against recovering protected information from integrated circuits. Existing defense methods are expensive in area, power or both. Small-scale ICs used in embedded systems and IoT devices are expected to be safe and secure, and yet cannot afford the area and power overheads of the sophisticated defense methods. This paper presents a design methodology for finite state controllers (FSMs) to defend against power analysis attacks while ensuring low power overhead. Further, a desired level of security can be achieved while minimizing power consumption. We formulate a set of constraints on state encoding based on security and power metrics. We express these constraints as a Boolean satisfiability (SAT) problem and use a SAT solver to generate constraint satisfying encodings. Using over 100 FSMs from BenGen and MCNC benchmark suites, experimental results show an average power reduction of up to 40% with respect to secure-only FSMs and 4-20% reduction with respect to minimal encoding strategy. Trade-off between security and power is demonstrated as mutual information between power side-channel and Hamming attacks models varies between 0 and 2.