A Defense Mechanism for Differential Power Analysis Attack in AES

In modern wireless communication world, the security of data transfer has been the most challenging task. In embedded system, AES is the most extensively used cryptographic algorithm in practice. But its functionality has been disrupted by the DPA attack. There have been several countermeasures to tackle those attacks, but this study proposes variably a new measure to defend this DPA attack. DPA attack is possible due to the power fluctuation happening due to sequential circuit clocking during the process of substitute byte in AES encryption in the first round and last round. Hence to prevent this, the power variation is maintained at a constant pace throughout the data processing. This is achieved by incorporating a combinational logic design instead of a sequential logic circuit in AES. The proposed design is implemented in Vertex III FPGA device and found even after 17230 power traces the secret key is not disclosed as the power fluctuations is completely random. The power consumption when experimented by micro wind software proves to be constant and the same power (almost) is obtained while implementing it hardware and no chance of identifying the instant of data processing is achieved.