Method for effecting an electronic payment transaction having a variable number of payment units, as well as payment means and system for applying the method

摘要

The invention relates to a method for protected payment with electronic payment device, such as "intelligent" payment cards ("smart cards"), in a variable number of steps. In this connection, use is made of a non-reversible function, of which successive function values are provided by the payment device to the payment station in question by way of proof of payment. On the basis of these function values, there may take place both a verification and a determination of the number of steps. Such method finds application, e.g., in public telephones and in copiers. The invention further relates to a payment device and a payment system for applying the method.