A Diversity Model Based on Failure Distribution and its Application in Safety Cases

This work develops a new basis for evaluating the reliability benefits of diverse software, based on fault injection testing. In particular, the work investigates new forms of argumentation that could in principle be used to justify diversity as a basis for the construction of safety claims. Failure distributions of two versions of diverse software under various fault conditions are revealed separately by fault injection methods, and then the common failure probability of the version-pair can be estimated. The approach is justified theoretically, and cross validated with other work. This method is also used to explain the fundamental influence of failure distributions on diversity. Furthermore, the unique capabilities of the method are demonstrated by implementation of the fault injection test on a program pair.