The present invention relates to a method and apparatus for preventing the use of data transmitted by a computer to a web site by a program operating on the computer. Initially, a first association between a set of labels and a first set of codes is created. The set of labels contains information to be displayed on the computer, while each code in the first set of codes is associated with a particular label. An encryption key is then linked with the first association. The set of labels, the first set of codes, and the first encryption key is then sent to the computer. Some time later, codes from the first set of codes and the first encryption key are received back from the computer. The codes returned from the computer are then matched to labels from the set of labels using the first encryption key. Afterwards, subsequent associations between the set of labels and other sets of codes are created. These associations are different than the association between the set of labels and the first set of codes. Additional encryption keys are also created to identify the subsequent associations. The present invention also relates to a method and a computer program product for determine the meaning of a code that describes a user's selection of an item on a web page. In this mode of operation, the information that defines the web page is first analyzed. Then, an association between the codes and labels presented on the web page is created. Afterwards, the code describing an item selected by a user is captured. Finally, the label associated with the code is identified by referencing the association between the codes and labels.