Various systems and methods for using power challenges to authenticate network devices are disclosed herein. For example, one method involves initiating a power challenge to authenticate an endpoint device, which involves, at least in part, requesting the endpoint device to perform a specific power signature; receiving data indicating whether the endpoint device performed the requested power signature within a given time interval, wherein the data can be received from, e.g., a power interface or other device capable of observing the endpoint device; processing the received data to determine if the endpoint device correctly performed the requested power signature; and if the endpoint correctly performed the power signature, authenticating the endpoint.