On a cryptographical characterization of classical and nonclassical event systems

Systems of numerical events, defined by how the probability of occurrence of an event depends on the state of the physical system, and fields of events which are related to ring-like logics, are characterized under a common viewpoint by a property which is characteristic of symmetric ciphers. A method is established which allows to separate the classical and the quantum behaviour in a way similar to the procedure related to Bellʹs inequalities, yet of a different nature.