Strengthening SIMON Implementation Against Intelligent Fault Attacks

Driven by malicious intent, attackers are impelled to extract the cipher key and thus compromise the cryptosystem through fault attacks. Existing fault-detection methods can effectively detect random faults in the cipher implementation, but yield a high fault bypass rate (FBR) under intelligent fault attacks. To address this limitation, we propose a new microarchitecture to thwart fault attacks that place mathematically symmetric faults on the two encryption data paths. To further reduce the FBR for a new lightweight cipher SIMON, we propose a new countermeasure that integrates operand permutation and masking techniques. Closed-form expressions for depermutation and demasking in SIMON are provided in this letter. Our method was assessed under two fault attack scenarios (random and symmetric fault injections) with bit-flip, stuck-at-0, and stuck-at-1 fault models. Simulation results show that our method minimizes the FBR to zero with the fault attack scenarios of symmetric fault location and stuck-at-0 fault injections. Overall, the proposed method outperforms the existing fault-detection methods in multiple fault attack conditions, at the cost of 5% more area overhead than the most hardware-efficient fault detection method.