Model-Based Security Engineering with UML: Introducing Security Aspects

Developing security-critical systems is difficult and there are many well-known examples of security weaknesses exploited in practice. Thus a sound methodology supporting secure systems development is urgently needed. Our aim is to aid the difficult task of developing security-critical systems in a formally based approach using the notation of the Unified Modeling Language. We present the extension UMLsec of UML that allows one to express security-relevant information within the diagrams in a system specification. UMLsec is defined in form of a UML profile using the standard UML extension mechanisms. In particular, the associated constraints give criteria to evaluate the security aspects of a system design, by referring to a formal semantics of a simplified fragment of UML. In this tutorial exposition, we concentrate on an approach to develop and analyze security-critical specifications and implementations using aspect-oriented modeling.