Miodrag Potkonjak Ani Nahapetian Michael Nelson Tammara Massey Hardware Trojan horse detection using gate-level characterization. 688-693 2009 DAC http://doi.acm.org/10.1145/1629911.1630091 conf/dac/2009 db/conf/dac/dac2009.html#PotkonjakNNM09