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

Abstract

Abstract-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 Index Terms-Software Diversity, Safety Case, Safety Critical System, Fault Injection, Multi-version, Reliability. Abbreviations: AFRAverage failure rate CFP Common failure probability EL Eckhardt and Lee FD Failure distribution FI Fault injection IFP s-Independent failures model LM Littlewood and Miller MR Meulen and Revilla MSF Mmodified sign function NVP New version-pair RI Reliability improvement SFP