An energy-based attack flow for temporal misalignment coutermeasures on cryptosystems
Rodrigo Lellis, Rafael Iankowski Soares, A.A. de Souza · 2017
Differential power analysis (DPA) and differential electromagnetic analysis (DEMA) are powerful type of attack enabled to discover confidential information processed on cryptosystems. These attacks are very sensitive to temporal desynchronization of processing caused by countermeasures. DPA based on energy calculation to realign traces is a solution found in the literature. However, in those proposals, the complete trace must be processed and issues such as the number of samples in the segment used to calculate energy traces and its effects on the attack are not discussed. This paper proposes an attack flow able to realign traces disturbed by random frequency and time shift countermeasures based on three steps: signature extraction, subsampling and energy calculation. This proposal evaluates the suitable segment length to improve the efficiency of the DEMA attack applied to a hardware implementation of the DES (Data Encryption Standard) algorithm prototyped in FPGA. Results highlight a reduction of up to 93.69% in the number of traces required for a successful attack when segments are sized to approximately half the clock cycle of the cryptosystem operating frequency.