A system and method for producing a massive number of diverse program instances so as to deter differential attacks, collusion, and similar hostile actions. Code portions are shown to be defined in various manners, instantiated, and aggregated. The system and method establishes a very large number of program instances that may be deployed. Furthermore, testing is accomplished over a minimal set of instances to provide for high test coverage and high confidence over the fully deployed instance set without incurring a high testing penalty.