Computer Safety, Reliability, and Security

Dependability case, assurance case, or safety case is employed to explain why all critical hazards have been eliminated or adequately mitigated in mission-critical and safety-critical systems. Goal Structuring Notation (GSN) is the most employed graphical notation for documenting dependability cases. System Theoretic Process Analysis (STPA) is a technique, based on System Theoretic Accidents Model and Process (STAMP), to identify hazardous control actions, scenarios, and causal factors. STPA is considered a rather complex technique, but there is a growing interest in using STPA in certifications of safety-critical systems development. We investigate how STAMP and STPA can be related to use of assurance cases. This is done in a generic way by representing the STPA steps as part of the evidence and claim documentations within GSN.