Abstract: A method for testing the authenticity of data carriers having integrated circuits, memory and logic means to determine physical properties of each circuit that are distinctive of this circuit and use them to obtain data characteristic of each circuit. According to the present invention, one preferably evaluates the different programming times of the memory cells of an E.sup.2 PROM memory, an evaluation which can be determined by various methods and processed as distinctive characteristics. Other individual properties that can be utilized are, for example, distinctive features of a memory input.

Abstract: The invention relates to a security document, in particular a bank note, identity card or the like, having a security element which is provided with characters, patterns, etc., visually readable at least in transmitted light and which is electrically conductive and bears additional substances for machine testing, and to a method for producing such a security element. The security element preferably consists of a transparent film strip that bears negative writing readily capable of visual checking and is additionally provided with electrically conductive and magnetic substances.