  Circuit obfuscation is a frequently used approach to conceal logic
functionalities in order to prevent reverse engineering attacks on fabricated
chips. Efficient obfuscation implementations are expected with lower design
complexity and overhead but higher attack difficulties. In this paper, an
emerging obfuscation approach is proposed by leveraging spinorbit torque (SOT)
devices based look-up-tables (LUTs) as reconfigurable logic to replace the
carefully selected gates. It is essentially impossible to identify the
obfuscated gate with SOTs inside according to the physical geometry
characteristics because the configured functionalities are represented by
magnetization states. Such an obfuscation approach makes the circuit security
further improved with high exponential attack complexities. Experiments on MCNC
and ISCAS 85/89 benchmark suits show that the proposed approach could reduce
the area overheads due to obfuscation by 10% averagely.
