Differential power analysis attack on ARM based AES implementation without explicit synchronization

This paper presents Differential Power Analysis (DPA) attack on 32-bit ARM Cortex-M3 microprocessor. Attacked algorithm is unprotected Advanced Encryption Standard (AES) with 128-bit key. DPA attack is deployed on the ARM processor by measuring its instantaneous power consumption during encryption algorithm. Analyzed power consumption traces obtained from the measurement are out-of-sync as they would be during the realistic DPA attack without using trigger to synchronize the traces. Unaligned traces or regular methods of static alignment are inappropriate for further analysis. In this paper elastic alignment methods are used for the trace synchronization. Dynamic Time Warping (DTW) and its fast algorithm FastDTW are deployed in order to match similar patterns in reference and misaligned power consumption traces. Output of DTW - optimal path is then used for the alignment process. Aligned traces are used for further processing and evaluation of the DPA attack. The result is successful DPA attack on misaligned power consumption traces and recovery of the secret 128-bit key. Results are comparable with DPA attack using trigger to align power traces during measurement.