A Structural and SAT Analysis of SANSCrypt

As IP theft remains an important problem, and attacks against logic locking mechanisms are becoming more sophisticated, the complexity of proposed encryption schemes are also becoming more complex. One goal of adding complexity is to increase the required time to perform an attack by forcing the required SAT problems to become so unwieldy, or require so many individual solves, that it is infeasible to break the encryption in reasonable time. In this paper, by discussing an attack against one such scheme, we demonstrate a combination of structural and SAT instances can break a design.