This article presents an excerpt of the tutorial on hardware security delivered at the 2019 IEEE International Solid-State Circuits Conference [4] and an introduction to a performance scaling trend perspective for security primitives. The latter provides insight into the recent and foreseeable evolution of the state of the art, in terms of both technical advances and new directions to pursue. Technology trends are derived from new public databases summarizing the state of the art, such as the Physically Unclonable Function database (PUFdb) and the hardware security database ( HWsecdb). Also presented is a reasoned review of prior art in circuits and subsystems for hardware security, from the very basics to best-in-class silicon demonstrations. As the emphasis here is on ubiquitous (i.e., down to low-end devices) and alwayson security, this article focuses on solutions suitable for tightly energy- and area-constrained systems.