Akram Idani

Derivation of UML class diagrams as static views of formal b developments

Although formal methods provide excellent techniques for the precise description of systems, understanding these descriptions is often restricted to experts. This paper investigates a practical solution to assist the understanding of a formal specification, written in B, by providing a complementary view of the specification as UML class diagram. Our technique improves the state of the art by taking into account operations in the construction of the diagram, through the use of concept formation techniques. A documentation tool automates the approach. It has been applied to several specifications built independently of the tool.

Infrastructure dirigee par les modèles pour une intégration adaptable et évolutive de UML et B

One of the main objectives of software engineering is to develop well-structured and reliable systems. This explains the variety of approches for integrating formal and semi-formal methods ; especially those which produce B specifications from UML models. In this work, we try to unify these approaches in order to be able, on the one hand, to combine rules issued from these techniques, and on the other hand, to easily extend them. Our UML/B multi- modeling tool provides transformations from UML to B in an MDE architecture. We also proposed the notion of customizable rule which allows to adapt and extend existing approaches with respect to various abstraction levels: meta-model (M 2 ), model (M 1 ) or dual (M 1 /M 2 ).

Validation of IS Security Policies Featuring Authorisation Constraints

Designing a security policy for an information system IS is a non-trivial task. Variants of the RBAC model can be used to express such policies as access-control rules associated to constraints. In this paper, we advocate that currently available tools do not take sufficiently into account the functional description of the application and its impact on authorisation constraints and dynamic aspects of security. The authors suggest translating both security and functional models into a formal language, such as B, whose analysis and animation tools will help validate a larger set of security scenarios. The authors describe how various kinds of constraints can be expressed and animated in this context. The authors also present a tool support which performs this translation and report on a case study where animation and testing techniques were used to validate the security policy of a medical emergency information system.

B for Modeling Secure Information Systems

Several approaches dedicated to model access control policies (e.g. MDA-Security, SecureUML, UMLSec, etc.) have used the Model Driven Engineering paradigm in order to ensure a clear separation of business rules and constraints specific to a target technology. Their supporting techniques mainly focus on modeling and verification of security rules without taking into account the functional model of the application and its interaction with the security model. In order to take into account both models, we developed the B4MSecure platform. It is a Model Driven Engineering platform that allows to graphically model and formally reason on both functional and security models. It translates a UML class diagram associated to a SecureUML model into formal B specifications. The resulting B specifications follow the separation of concerns principles in order to be able to validate both models separately and then validate their interactions. This paper gives an overview of our platform.

From KAOS to RBAC: A Case Study in Designing Access Control Rules from a Requirements Analysis

This paper presents the KAOS2RBAC approach for Security Requirements Engineering. Starting from functional requirements, linked to a data model, the approach first identifies high level security goals. It then refines these security goals into security requirements linked to the functional model. Finally, these security requirements lead to the design of access control rules. An informal verification step checks that the rules give enough permission to enable all functional requirements. The approach takes benefit of the KAOS notations to link functional and non-functional goals, agents, data, and access control rules in a single requirements model. This enables traceability between security goals and the resulting access control rules. The approach is illustrated by a case study: an information system for medical urgency, taken from a real project.

When a Formal Model Rhymes with a Graphical Notation

Formal methods are based on mathematical notations which allow to rigorously reason about a model and ensure its correctness by proofs and/or model-checking. Unfortunately, these notations are complex and often difficult to understand from a human point of view especially for engineers who are not familiar with formal methods. Several research works have proposed tools to support formal models using graphical views. On the one hand, such views are useful to make formal documents accessible to humans, and on the other hand they ease the verification of some behavioral properties. However, links between graphical and formal models proposed by these approaches are often difficult to put into practice and depend on the targeted formal language. In this paper, we discuss these links from a practical approach and show how a behavioral description can be computed from a formal model based on two complementary paradigms: under-approximation (or animation-based) and over-approximation (or proof-based). We applied these paradigms in order to produce behavioural state/chart views from B models and we carried out an empirical study to assess the quality and relevance of these graphical representations for humans.

Extensions du diagramme d'activité pour la spécification de politiques RBAC

The evolution of organizations and their information systems towards more openness raises the challenge of their security. The definition of an access control policy is a major activity in the design of an Information System. This paper proposes an approach for the specification of security policies, based on the RBAC model, at the workflow level. This approach propagates permissions defined on a class diagram, using the SecureUML profile, towards constraints linked to the business process activities. Activity diagrams are defined at two levels : an abstract level which does not detail these permissions and a concrete level where constraints are associated to specific actions or to the whole diagram. A metamodel was been defined in order to specify the semantics of these activity diagrams and the semantics of their links with SecureUML models. This paper presents an extended version of (Chehida et al., 2015), which proposes a set of rules to ensure consistency between the concrete activity models and SecureUML models, and the implementation of these rules in a tool that reports all contradictions between both models. MOTS-CLÉS : RBAC, Workflow, processus métier, SecureUML, UML2, diagramme d’activité, cohérence.

Approche formelle pour la dérivation de vues structurelles UML à partir de développements B : Formalisation, preuve et extension pour la prise en compte des raffinements B

Formal methods are nowadays one of the most rigorous ways to develop software and model systems. But their notations are complex which prevents their adoption. In fact, formal models remain difficult to read when they are not well documented. In a previous work we proposed a reverse-engineering framework which allows to graphically document B specifications by automatically deriving structural UML views. Our approach is based on a concept formation technique. In this paper, we formalize our algorithm and we prove that the generated context models satisfy a set of pertinency criteria. Finally, we show how our technique can be used in order to take refinements into account.