Assurance Case Driven Design for Computer Systems: Graphical Notations versus Mathematical Methods

Assurance (Security and Safety) Case is a proven-in-use methodology to demonstrate a system compliance with security and safety critical requirements. An advance approach to improve Assurance Case is proposed in a view of Assurance Case Driven Design (AC DD). A practical using of AC DD lays in cost-effectiveness improvement of certification and licensing processes Assurance Case is based on graphical notations. These graphical notations are a part of formal methods, which originally are developed from classical mathematical models and methods. In this article we propose turn back to the set theory and graph theory which are the original fundamentals of Assurance Case. That allows as us to implement a kind of reverse engineering for a formal notation. We analyze basic mathematical models and methods to improve a known formal notation at the top level. As a result we develop Claim-Argument-Evidence-Criteria (CAEC) notation as well as Development-Verification & Validation-Assurance Case (DVA) notation for AC DD implementation.