Assurance cases are structured arguments used to demonstrate specific system properties such as safety or security. They are used in many industrial sectors including automotive, aviation and medical devices. Assurance cases are usually divided into modules which address goals allocated to specific system properties, components, functions, modes of operation or environmental conditions. Depending on the system and assurance process characteristics, assurance case modules may follow shared argument templates. The templates refer to the system, process or environment attributes, described collectively as an assurance case context and stored in external context models. Our goal is to manage all contextual relations at the level of assurance case templates and instantiated arguments with the use of a generic System Assurance Reference Model (SARM). We describe its structure and demonstrate how it can be used to automatically generate assurance case modules, based on templates and context models. The article also presents a prototype tool, SARMER, which implements the SARM model and enables automatic data flow between models and assurance cases. The use of SARM and the SARMER tool is illustrated with an example of a component-based system and a modular assurance case to demonstrate that allocated contracts are satisfied for each component.

Assurance cases are structured arguments used to demonstrate specific system properties such as safety or security. They are used in many industrial sectors including automotive, aviation and medical devices. Larger assurance cases are usually divided into modules to manage the complexity and distribute the work. Each of the modules is developed to address specific goals allocated to the specific objects i.e. components of the system’s architecture. Such goals are applicable for given conditions of use, for instance, operational modes or target environments. It is recommended that the complete context of each of the argument modules, encompassing information about systems/components, goals and conditions of use, is described explicitly to enable efficient management and proper use of each module. This becomes even more important for component-based design, including the use of out-of-context components. In this paper, we describe a concept of a generic System Assurance Reference Model (SARM), which bridges the gap between assurance cases and the related context models. We identify the key factors that condition the high-level assurance case structure, explain how they can drive its decomposition into assurance case modules and outline the process of creating and using context models. We present a prototype solution which implements the SARM model and enables automatic data flow between models and assurance cases.