Automated Generation of Modular Assurance Cases with the System Assurance Reference Model

Abstract

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 paper 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.