Theoretical simple power analysis of the grain stream cipher

Power analysis has come to be an important category of cryptanalytic attacks. Although such attacks have been extensively applied to block ciphers, only limited research has been done to analyze their effectiveness on stream cipher hardware implementations. In this paper, we consider the application of simple power analysis (SPA) to the Grain stream cipher. The applicability of SPA is considered under idealized assumptions of the Hamming distance power model and the complexity of the attack is analyzed. The resulting analysis implies that the Grain cipher is susceptible to power analysis attacks where there is strong correlation between the power measurements and changes in the cipher´s state registers.