Special CD-keys are generated so as to have special patterns recognizable by compliant installer programs, which require special actions to be taken by the compliant installer programs when recognized. Since the special patterns are different than those used for valid CD-keys, non-compliant installer programs will treat them as invalid CD-keys and refuse to install any computer programs for which the invalid CD-keys are provided. The special CD-keys are included in text files that have associated metadata indicating that they are for installing copies of computer programs to be protected. The text files are then offered by agent computers for downloading on file sharing networks.