Abstract: Methods, systems and techniques are provided to authenticate a device under test (DUT)/system under test (SUT) comprising an electronic component(s). A profile is defined by injecting a signal to elicit an output that is responsive a physical characteristic of the type of DUT/SUT. In respective embodiments the injected signal is defined to elicit an output for time-domain or frequency-domain evaluation. An injected signal may comprise combinations of (non-destructive/non-activating) signals applied to multiple access points for measurement at arbitrary access points of the DUT/SUT. In an embodiment, measurements of multiple DUT/SUTs of a same type are used to define a common profile. In an embodiment, the profile is built using machine learning to define a classifier. In other embodiments, statistical profiles are defined. During use, output is generated for a target DUT/SUT for evaluation relative to the profile. Counterfeit/alternate designs, altered designs, and implants are detectable.