FSMLock: Sequential Logic Locking Through Encryption

FSMLock is a new sequential logic locking technique that utilizes classical cryptographic block cipher algorithms to conceal and restrict access to the targeted finite state machine (FSM). Unlike other FSM-based sequential logic locking techniques, FSMLock adds no additional states to the state transition graph (STG). Instead, FSMLock is applied to a sequential circuit by abstracting a flattened version of its distinct state entry table (SET) into a binary data file, which can then be encrypted and stored in non-volatile memory (NVM). The encrypted flattened stats entry table (FSET) information is read in partitions such that, at run-time, only a subset of the sequential logic is in scope. The resulting architecture has a theoretical resistance against removal attacks, circuit unrolling-based satisfiability (SAT) attacks, and topological/boolean functional analysis attacks. This is due to the SAT-hard abstraction as an encrypted binary data file of the locked circuitry.