Power analysis of a FPGA implementation of SM4

SM4 (SMS4) algorithm is a block cipher used in the Chinese National Standard for WLAN WAPI. In this paper we investigate the vulnerability of SM4 FPGA (Field Programmable Array) implementation to differential power analysis (DPA). To tackle this issue, we review the theory behind the conventional DPA on DES and AES first. By comparing the differences in algorithm structure, we show that SM4 is more difficult to attack than DES and AES. Then, we concentrate on showing how “chosen-text DPA” can be applied to attack SM4 successfully while the conventional DPA is hardly effective. Experimental results against a FPGA implementation of SM4 demonstrate the inefficient of conventional DPA and the effectiveness of “chosen-text DPA”. In addition, proper countermeasures for SM4 are also discussed according to its DPA-related properties.