Gate level obfuscation using programable contacts is one of the techniques used for obfuscating the netlist to defend against netlist reverse engineering. Using this technique, a designer implements obfuscation so that it is not clear to the attacker whether the obfuscated gate G$1$ is XOR, NOR, or NAND during netlist reverse engineering. During the netlist reverse engineering process, the attacker places a placeholder G$1$ and measures the output O with various the input vectors I$1,$I$2,$I$3,$I$4,$I$5$ for a working IC obtained from open market. Using this technique, the attacher tries to resolve if G$1$ is XOR, NOR, or NAND gate. The attacker observes O$=1$ for input I$1,$I$2,$I$3,$I$4,$I$5=\{0,0,0,0,0\}.$ This observation eliminates the possibility that G$1$ is:

Exam$2-$Obfuscation$-1-$Fig.png

Group of answer choices

NAND

XOR

NOR

Cannot resolve