Function Masking: A New Countermeasure Against Side Channel Attack

Masking schemes have been developed to implement secure cryptographic algorithms against Side Channel Analysis(SCA) attacks. Technically, the first-order masking method is vulnerable to the second order Differential Power Analysis(2ODPA) attacks, but the current solutions against 2ODPA are expensive to implement. Moreover, worse performance will be shown if the cryptographic algorithms include boolean and arithmetic operations. In this paper, we propose a new masking scheme to resist SCA attacks, which is called the Function Masking. Function Masking method conceals functions instead of data in the algorithms and makes it resistant to attacks as much as 2ODPA. We apply our masking scheme to the HIGHT algorithm. The encryption of function masked HIGHT takes only 1.79 times more than one of the original algorithm, even though it needs 25 kbytes to store lookup tables in memory.