Using SAT Solving to Improve Differential Fault Analysis of Trivium

Combining different cryptanalytic methods to attack a cryptosystem became one of the hot topics in cryptanalysis. In particular, algebraic methods in side channel and differential fault analysis (DFA) attracted a lot of attention recently. In [9], Hojśik and Rudolf used DFA to recover the inner state of the stream cipher Trivium which leads to recovering the secret key. For this attack, they required 3.2 one-bit fault injections on average and 800 keystream bits. In this paper, we give an example of combining DFA attacks and algebraic attacks. We use algebraic methods to improve the DFA of Trivium [9]. Our improved DFA attack recovers the inner state of Trivium by using only 2 fault injections and only 420 keystream bits.