Propositional satisfiability (SAT) is at the nucleus of state-of-the-art
approaches to a variety of computationally hard problems, one of which is
cryptanalysis. Moreover, a number of practical applications of SAT can only be
tackled efficiently by identifying and exploiting a subset of formula's
variables called backdoor set (or simply backdoors)...
This paper proposes a new
class of backdoor sets for SAT used in the context of cryptographic attacks,
namely guess-and-determine attacks. The idea is to identify the best set of
backdoor variables subject to a statistically estimated hardness of the
guess-and-determine attack using a SAT solver. Experimental results on weakened
variants of the renowned encryption algorithms exhibit advantage of the
proposed approach compared to the state of the art in terms of the estimated
hardness of the resulting guess-and-determine attacks.