An Integrated Circuit (IC) can be reverse engineered by imaging its layout and reconstructing the netlist. IC camouflaging is a layout-level technique that hampers imaging-based reverse engineering by using, in one embodiment, functionally different standard cells that look alike. Reverse engineering will fail if the functionality of a camouflaged gate cannot be correctly resolved. We adapt VLSI testing principles (justification and sensitization) to quantify the ability of a reverse engineer to unambiguously resolve the functionality of look-alike camouflaged gates. We evaluate the security of look-alike standard cells based IC camouflaging by applying it on the controllers in OpenSPARC T1 processor.