Goal-based requirement engineering for fault tolerant security-critical systems

Large amount of security faults existing in software systems could be complex and hard to identify during the fault analysis. Therefore, it is not always possible to fully mitigate the internal or external security faults (vulnerabilities or threats) within the system. On the other hand, existence of faults in the system may eventually lead to a security failure. To avoid security failure of the target system it is required to make the system flexible and tolerant in the presence of security faults. This paper proposes a goal-based modeling approach to develop security requirements of Security-Critical Systems (SCSs) through explicitly factoring the faults into the requirement engineering process. Our approach establishes the Security Requirement Model (SRM) of the system based on its respective Security Fault Model (SFM). We incorporate fault tolerance into the SRM through considering the partial satisfaction of security goals. The proposed approach factors this partiality into the goals by using proper mitigation techniques during the refinement process. This approach eventually contributes to a fault tolerant model for security requirements of the target system ©2013 SERSC.