Monia Loulou

Formalization of Cooperation in MAS: Towards a Generic Conceptual Model

This paper proposes a formal definition of a conceptual model for cooperation among multi-agent systems (MAS). This works constitutes a part of a general research project aiming at defining a generic interaction model that covers the different facets of the cooperative activity among MAS. We propose a framework for the specification, design and verification of interaction mechanisms. Doing so, and using the Z notation, we bring closer the concepts describing a cooperative activity while integrating them with the concepts related to the organizational modelling within a MAS. Moreover, we suggest a set of necessary properties needed to maintain the consistency at the individual level (Agent) as well as at the collective level (System). The syntax and the semantic of proposed specifications have been validated with the Z-eves verification tool [1].

A Conceptual Model for Secure Mobile Agent Systems

This work constitutes a part of a general research project aiming at defining a generic framework for developing secure mobile agent systems stamped with a lack of consensus about their fundamental concepts. In order to facilitate analysis, design and specification of mobile agent systems, we present in this paper a brief definition and relationship among most key concepts for modeling a mobile agent system and the interaction within such dynamic environment. In order to overcome the possible attacks that may occur in a mobile agent system, we must associate the specification of the basic concepts that ensuring security such as: agent authenticity, authority access, security policy and its various kind. The syntax and the semantic of the proposed specifications have been checked using the Z-EVES tool

Dynamic security framework for mobile agent systems: specification, verification and enforcement

We define in this paper, a formal conceptual model, which presents the most fundamental concepts for mobile agent systems and unifies their representation and defines the relations between them. On this base, we propose a formal security framework which consists of three basic frameworks. The specification framework proposes a generic definition of security policies for the entities of mobile agent systems. The verification framework checks the intra-policy consistency. The reconfiguration framework describes how to reconfigure security policies and to maintain their consistency. Finally, we examine this theoretical work by defining an operational framework for dynamic enforcement of security policies.

A Formal Approach to prevent Attacks on Mobile Agent Systems

One of the most important issues in mobile agent systems is the security aspect. For the purpose of ensuring security, we provide in this paper a formal model for secure mobile agent system. This model supports the specification of numerous security policy types which control the behaviour of system entities and protect them, as far as possible, from attacks that may occur. In order to verify whether a security policy could overcome a given kind of attack, we present a formal approach to this end. Thus, we propose a precise and formal representation of possible attacks that may occur in a mobile agent systems. According to this representation, we define a set of proved theorems which describe under what conditions a policy succeeds to prevent those attacks. The proposed specifications have been formalized using Z notation and checked using the Z-EVES tool.

Multi-tenant Services Monitoring for Accountability in Cloud Computing

Software as a Service (SaaS) is a delivery model in which software resources are accessed remotely by users. Multi-tenancy is one of key properties of SaaS to achieve higher profit margin by leveraging the economies of scale. This feature empowered by virtualization comes several new complexities introduced related to the area of accountability. For this purpose, we tackle the problem of integrating multi-tenancy in cloud services accountability and determine crucial issues that can be solved. To do this, we propose a multitenant services monitoring approach that keeps monitoring service execution at runtime and detecting privacy violations. This approach is based on multitenant accountability patterns for integrating multi-tenancy architecture and expressing rules that are enforced using AOP. Furthermore, we propose a middleware layer for implementing our approach into conventional cloud architecture. The performed evaluation proves the flexibility and the efficiency of our approach for services based applications in the cloud computing.

Modeling secure mobile agent systems

We propose a MDA based approach for designing secure mobile agent systems. First, we define a meta-model which extends the UML deployment diagram by concepts related to the security and mobility of multi-agent systems. We propose also a UML profile as an implementation of this meta-model. Second, we project the application model into AGLETS-specific model, which describes the main functionalities of the application deployed on AGLETS as a mobile agent platform.

Analyzing Multi-tenant Cloud Services' Accountability

Analyzing accountability violations and identifying the guilty party is a challenging process especially where multiple tenants are hosted by a single application instance. To handle this issue, we propose an approach for accountability violation analysis. It is based on service patterns as an abstract model to provide reusable and suitable description of the different characteristics of the analysis process, and an algorithm for pattern selection and instantiation. Furthermore, we propose a middleware layer for implementing our approach on the top of application level.

Formal Security Framework for Agent Based Cloud Systems

The adoption of cloud computing becomes hampered by the emergence of security problems. We aim in this paper to define a framework which clarifies the concepts of security in a cloud environment and can afterwards check a number of security properties. To achieve this objective, we propose a three-level approach: Modeling, Specification and Verification. In the first step, we propose an agent based modeling of cloud architecture in order to leverage the capabilities of software agents and consequently to reduce complexity. In specification step, we formally specify the concepts evoked in the modeling step and enrich them by others related to security. In the last step, we proceed to verify the security level in cloud environments in order to better control their entities behaviour.

RDyMASS: reliable and dynamic enforcement of security policies for mobile agent systems

Defining security policies is a crucial stage for an efficient implementation of security within mobile agent systems.To enforce these policies in a reliable way, it is necessary to make use of formal techniques which offer enough flexibility and expressiveness, and which provide a rigorous reasoning about the security of mobile agent systems security. The migration of the agent between several systems can lead to inconsistencies between its policy and the policy of the system. These incoherencies may require a dynamic reconfiguration of the security policies of the system and the agent. This reconfiguration cannot be efficient without the use of mechanisms that improve the modularity of the security code. In this paper, we aim to dynamically enforce security policies in mobile agent systems in modular and reliable way. For this purpose, we combine formal methods and aspect oriented programming. We propose a three-step approach to enforce security policies in the form of aspects that will be generated through a reliable specification of security policies.

A formal security framework for mobile agent systems: Specification and verification

Security in mobile agent systems is twofold: protection of mobile agents and protection of agent execution system. Indeed, the proposed solutions for the security of distributed systems arenpsilat sufficient. Moreover, therepsilas no solution which treats the different concerns of security in the mobile agent systems. To achieve this goal, we use formal foundations which provide a rigorous reasoning about security of mobile agent systems. We propose in this paper a formal framework for the security in mobile agent systems which consists of three basic frameworks. The specification framework proposes, explicitly, a generic definition of security policies that may be enhanced by several concepts related to one or more security models. For illustration, we present a security policy enhancement based on the concepts of the RBAC model. Inevitably, we associate to the specification framework a verification framework which checks the consistency of the proposed specifications as well as the consistency intra-policy. In response to the dynamic changes of security requirements in mobile agent systems, we propose a third framework for the reconfiguration of policies.