Charge-Withheld Converter-Reshuffling: A Countermeasure Against Power Analysis Attacks

Converter-reshuffling (CoRe) technique has recently been proposed as a power-efficient countermeasure against differential power analysis (DPA) attacks by randomly reshuffling the individual stages within a multiphase switched-capacitor voltage converter. This randomized reshuffling of the converter stages inserts noise to the monitored power profile and prevents an attacker from extracting the correct input power data. The total number of activated phases within a switch period, however, still correlates with the dynamic power consumption of the workload. To break the one-to-one relationship between the monitored and actual power consumption, a charge-withheld CoRe technique is proposed in this brief by utilizing the flying capacitors to withhold a random amount of charge for a random time period. As compared to the conventional CoRe technique, the proposed charge-withheld CoRe technique eliminates the possibility of having a zero power trace entropy (PTE) even under machine-learning-based DPA attacks. The average PTE of the monitored power profile is increased ~46.1% with a 64-phase charge-withheld CoRe technique.