Method for secure data transmission in selling products

A method is proposed for transmitting product-specific data in a manner protected against imitation by means of one or more information carriers for the process of purchasing products, whereby in the process the selection of the products and the delivery thereof is realized in spatially separated zones. The information carriers are provided as a (paper) document, a transponder, a chip or a chip card (smart card), wherein self-checking encryption codes which are independent from each other and which are provided on each of said information carriers ensure a correct product delivery.