Functional Analysis Attacks on Logic Locking
This paper proposes Functional Analysis attacks on state of the art Logic Locking algorithms (abbreviated as FALL attacks). FALL attacks have two stages. The first stage identifies nodes involved in the locking functionality and analyzes functional properties of these nodes to shortlist a small number of candidate locking keys. In many cases, this shortlists exactly one locking key, so no further analysis is needed. However, if more than one key is shortlisted, the second stage introduces a SAT-based algorithm to identify the correct locking key from a list of alternatives using simulations on an unlocked circuit. In comparison to past work, the FALL attack is more practical as it can often succeed (90 locked netlist, without requiring oracle access to an unlocked circuit. Further, FALL attacks successfully defeat Secure Function Logic Locking (SFLL), the only locking algorithm that is resilient to known attacks on logic locking. Our experimental evaluation shows that FALL is able to defeat 65 out of 80 (81
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