A method and system for authenticating goods and thereby detecting and deterring counterfeits are disclosed. According to one aspect of the invention, a client utilizes data received from a host to generate a plurality of security codes and to direct a printing device to print the plurality of security codes on a plurality of products, without retaining the plurality of security codes after the printing device has printed the plurality of security codes on the plurality of products. After the security codes have been printed, a person can communicate the security code to the host, which can verify its authenticity.