Abstract: A simple and cost effective system of marking products for authentication, preventing surplus production and tracking purpose is described. The system requires computer hardware and software where the calculation and verification of encrypted sequences can be carried out. Depending on the kind of product, its value and production process the economically best solution can be chosen to deliver or affix the encrypted sequence with each peace of product. Authorities, dealer or consumer can proof the authenticity in real-time at any place by verifying encrypted sequences. By testing the consistency of encrypted sequences and subsequent tests by comparing data retrieved from the input device with data stored on a computer system a product can be determined as original or falsification. Subsequent tests are necessary to recognize illegal usage of valid sequences. The result is recorded and reported in real time back to the enquirer or other defined parties.