Efficient Random Number for the Masking Method against DPA Attacks

Security LSI which is implemented on IC cards conducts the encryption processing to protect confidential information such as cipher keys. In the encryption, encryption standards such as DES algorithm and AES algorithm are widely used and are theoretically secured. However, when these encryption standards are incorporated into electronic devices, it is reported to be possible to estimate the confidential information by analyzing the secondary information such as power consumption during the circuit´s operation. The transformed masking method is a typical measure against this attack at the algorithm level. In this method, adding random numbers to intermediate data of encryption masks the correlation between power consumption and confidential information. The transformed masking method is effective for hamming weight attack that focuses on the bit value. This study clarifies random numbers used in the transformed masking method that are effective for this attack. Experimental results show the validity of the proposed method.