Abstract: Counterfeit articles are distinguished from genuine articles by a combination of a party-specific code and a product authentication code of the article. After authenticating a genuine article, a replacement authentication code is generated based on the original authentication code and party-specific code. Documents and currencies can be authenticated independently of any party-specific code by an addition to or alteration of their authentication code with each authentication event.

Abstract: A circuit board or each circuit board of a multi-layer circuit board includes an electrically conductive sheet coated with an insulating top layer covering one surface of the conductive sheet, an insulating bottom layer covering another surface of the conductive sheet and an insulating edge layer covering an edge of the conductive sheet. An insulating interlayer can be sandwiched between a pair of adjacent circuit boards of a multi-layer circuit board assembly. A landless through-hole or via can extend through one or more of the circuit boards for connecting electrical conductors on opposing surfaces thereof.