A camouflage circuit instantiated on a semiconductor substrate includes a transient-comparison circuit that briefly expresses a value representative of either a one or a zero in dependence upon reference elements that are visibly indistinct from a perspective normal to the planar surface substrate surface, but that nevertheless exhibit distinct electrical responses. Transient comparisons that define logic states only briefly vastly complicate the use of reverse-engineering tools and techniques that rely on optical stimulation to sense when transistors are on or off.
