Improved Differential Fault Analysis of CLEFIA

CLEFIA is already shown to be vulnerable to differential fault analysis (DFA). The existing state-of-the-art DFA shows that two faults are enough to break CLEFIA-128, whereas for CLEFIA-192 and CLEFIA-256 ten faults are needed. Side-by-side it emphasizes the need for protecting last four rounds of the cipher in order to make it secure against the attack. In this paper we propose an improved DFA on CLEFIA. The analysis shows that an attack is possible even if the last four rounds of CLEFIA are protected against DFA. Further, the proposed attacks on CLEFIA-192 and CLEFIA-256 show that 8 faults are sufficient to successfully retrieve the 192 and 256-bit key respectively. The work shows improvement over the previous work. Extensive simulation results have been presented to validate the proposed attack. The simulation results show that the attack can retrieve the 128-bit secret key in around one minute of execution time whereas the attack on 192 and 256-bit key requires around one second to retrieve the secret key.