On the Impact of Aging on Power Analysis Attacks Targeting Power-Equalized Cryptographic Circuits.

Side-channel analysis attacks exploit the physical characteristics of cryptographic chip implementations to extract their embedded secret keys. In particular, Power Analysis (PA) attacks make use of the dependency of the power consumption on the data being processed by the cryptographic devices. To tackle the vulnerability of cryptographic circuits against PA attack, various countermeasures have been proposed in literature and adapted by industries, among which a branch of hiding schemes opt to equalize the power consumption of the chip regardless of the processed data. Although these countermeasures are supposed to reduce the information leak-age of cryptographic chips, they fail to consider the impact of aging occurs during the device lifetime. Due to aging, the specifications of transistors, and in particular their threshold-voltage, deviate from their fabrication-time specification, leading to a change of circuit’s delay and power consumption over time. In this paper, we show that the aging-induced impacts result in imbalances in the equalized power consumption achieved by hiding countermeasures. This makes such protected cryptographic chips vulnerable to PA attacks when aged. The experimental results extracted through the aging simulation of the PRESENT cipher protected by Sense Amplifier Based Logic (SABL), one of the well-known hiding countermeasures, show that the achieved protection may not last during the circuit lifetime.