Integrated all-digital low-dropout regulator as a countermeasure to power attack in encryption engines

Low-drop-out (LDO) voltage regulator modules are being increasingly integrated in the modern processors for efficient power management. This paper shows that an integrated All-Digital LDO (ADLDO) can also be used as a countermeasure against power measurement based side channel attacks. The current transformation introduced by integrated digital LDOs, coupled with the noise due to quantization and limited sampling rate in the control loop, helps suppress the side channel leakage. The ADLDO-based countermeasure is analyzed considering an Advanced Encryption Standard (AES) engine designed in 130nmCMOS. Correlation power analysis and signal-to-noise ratio of the current waveforms at the input of the ADLDO shows significant improvement in power attack resistance over the AES input current.