Identification of deterministic sequential finite state machines in unknown CMOS ICs

Until now the efficient identification of unknown CMOS integrated circuits (ICs) has attracted a lot of interest. In particular, different invasive and non-invasive strategies have been developed for IC identification. However, invasive procedures always lead to the destruction of device under test. The non-invasive approaches published so far have the disadvantage that ICs are analysed by using very complex and time consuming algorithms. This paper presents a novel non-invasive procedure to determine nonlinear binary multi-input multi-output (MIMO) ICs solely by their input-output behaviour. The algorithm presented in this paper identifies unknown ICs by the abstraction of traditional automata theory. The overall identification procedure was simulated and fully tested on IEEE ISCAS benchmark models as well as user defined models of real ICs. The results are presented in this paper. For every circuit analysed the function has been successfully determined by the proposed identification procedure.