Group Communication System Research Articles

Modeling and analysis of trust management with trust chain optimization in mobile ad hoc networks

We develop and analyze a trust management protocol for mission-driven group communication systems in mobile ad hoc networks using hierarchical modeling techniques based on stochastic Petri nets. Trust among mobile nodes is crucial for team collaborations with new coalition partners without prior interactions for mission-driven group communication systems in battlefield situations. In addition, ensuring a certain level of trust is also critical for successful mission completion. Our work seeks to identify the optimal length of a trust chain among peers in a trust web that generates the most accurate trust levels without revealing risk based on a tradeoff between trust availability and path reliability over trust space. We define a trust metric for mission-driven group communication systems in mobile ad hoc networks to properly reflect unique characteristics of trust concepts and demonstrate that an optimal trust chain length exists for generating the most accurate trust levels for trust-based collaboration among peers in mobile ad hoc networks while meeting trust availability and path reliability requirements.

Distributed Group Key Management with Cluster based Communication for Dynamic Peer Groups

Secure group communication is an increasingly popular research area having received much attention in recent years. Group key management is a fundamental building block for secure group communication systems. This paper introduces a new family of protocols addressing cluster based communication, and distributed group key agreement for secure group communication in dynamic peer groups. In this scheme, group members can be divided into sub groups called clusters. We propose three cluster based communication protocols with tree-based group key management. The protocols (1) provides the communication within the cluster by generating common group key within the cluster, (2) provides communication between the clusters by generating common group key between the clusters and (3) provides the communication among all clusters by generating common group key among the all clusters. In our approach group key will be updated for each session or when a user joins or leaves the cluster. More over we use Certificate Authority which guarantees key authentication, and protects our protocol from all types of attacks.

Performance analysis of hierarchical group key management integrated with adaptive intrusion detection in mobile ad hoc networks

We develop a mathematical model to quantitatively analyze a scalable region-based hierarchical group key management protocol integrated with intrusion detection to deal with both outsider and insider security attacks for group communication systems (GCSs) in mobile ad hoc networks (MANETs). Our proposed adaptive intrusion detection technique is based on majority voting by nodes in a geographical region to cope with collusion of compromised nodes, with each node preloaded with anomaly-based or misuse-based intrusion detection techniques to diagnose compromised nodes in the same region. When given a set of parameter values characterizing operational and environmental conditions, we identify the optimal intrusion detection rate and the optimal regional area size under which the mean time to security failure of the system is maximized and/or the total communication cost is minimized for GCSs in MANET environments. The tradeoff analysis in performance versus security is useful in identifying and dynamically applying optimal settings to maximize the system lifetime for scalable mobile group applications while satisfying application-specific performance requirements.

Model-Based Evaluation of Distributed Intrusion Detection Protocols for Mobile Group Communication Systems

Under highly security vulnerable, resource-restricted, and dynamically changing mobile ad hoc environments, it is critical to be able to maximize the system lifetime while bounding the communication response time for mission-oriented mobile groups. In this paper, we analyze the tradeoff of security versus performance for distributed intrusion detection protocols employed in mobile group communication systems (GCSs). We investigate a distributed voting-based intrusion detection protocol for GCSs in multi-hop mobile ad hoc networks and examine the effect of intrusion detection on system survivability measured by the mean time to security failure (MTTSF) metric and efficiency measured by the communication cost metric. We identify optimal design settings under which the MTTSF metric can be best traded off for the communication cost metric or vice versa. We conduct extensive simulation to validate analytical results obtained. This work provides a general model-based evaluation framework for developing and analyzing intrusion detection protocols that can dynamically adapt to changing attacker strengths with the goal of system lifetime optimization and/or communication cost minimization.

An implementation of a replicated file server supporting the crash-recovery failure model

Data replication techniques are widely used for improving availability in software applications. Replicated systems have traditionally assumed the fail-stop model, which limits fault tolerance. For this reason, there is a strong motivation to adopt the crash-recovery model, in which replicas can dynamically leave and join the system. With the aim to point out some key issues that must be considered when dealing with replication and recovery, we have implemented a replicated file server that satisfies the crash-recovery model, making use of a Group Communication System. According to our experiments, the most interesting results are that the type of replication and the number of replicas must be carefully determined, specially in update intensive scenarios; and, the variable overhead imposed by the recovery protocol to the system. From the latter, it would be convenient to adjust the desired trade-off between recovery time and system throughput in terms of the service state size and the number of missed operations.

Effect of Intrusion Detection on Reliability of Mission-Oriented Mobile Group Systems in Mobile Ad Hoc Networks

For mission-oriented mobile group systems designed to continue mission execution in hostile environments in the presence of security attacks, it is critical to properly deploy intrusion detection techniques to cope with insider attacks to enhance the system reliability. In this paper, we analyze the effect of intrusion detection system (IDS) techniques on the reliability of a mission-oriented group communication system consisting of mobile groups set out for mission execution in mobile ad hoc networks. Unlike the common belief that IDS should be executed as often as possible to cope with insider attacks to prolong the system lifetime, we discover that IDS should be executed at an optimal rate to maximize the mean time to failure of the system. Further, the optimal rate at which IDS is executed depends on the operational conditions, system failure definitions, attacker behaviors, and IDS techniques used. We develop mathematical models based on Stochastic Petri nets to identify the optimal rate for IDS execution to maximize the mean time to failure of the system, when given a set of parameter values characterizing the operational conditions, and attacker behaviors.

Design of mobile group communication system in ubiquitous communication network

The advent of ubiquitous IP networks enables users to freely move and continue network services anytime, anywhere by means of mobile handheld devices. This paper exploits network ubiquity and advanced device capability to develop a novel mobile group communication system. Our work presents the design and implementation of a proof-of-concept software system. This system architecture consists of four components: central tracking, handheld tracking, handheld messaging and Web-based administration subsystems. Their functional integration thus fulfills both location tracking and mobile messaging services in support of mobile group communication. After prototype and demonstration, the proposed system is able to offer a variety of novel location-aware and text/voice communication scenarios to mobile social communities in ubiquitous IP network environments.

Formal verification of secure group communication protocols modelled in UML

The paper discusses an experience in using Unified Modelling Language and two complementary verification tools in the framework of SAFECAST, a project on secured group communication systems design. AVISPA enabled detecting and fixing security flaws. The TURTLE toolkit enabled saving development time by eliminating design solutions with inappropriate temporal parameters.

Survey of security services on group communications

Secure group communication (SGC) has attracted much attention, as group-oriented communications have been increasingly facilitating many emerging applications that require packet delivery from one or more sender(s) to multiple receivers. Of all proposals reported, most have focused on addressing the issue of key management to SGC systems. The authors, however, advocate that security services are also needed to satisfy different security requirements of various applications. The authors also present here a survey on recent advances in several security requirements and security services in group communication systems (GCSs), illustrate some outstanding GCSs that deploy these security services, and describe challenges for any future research works in designing a secure GCS.

Modeling and analysis of intrusion detection integrated with batch rekeying for dynamic group communication systems in mobile ad hoc networks

We investigate performance characteristics of secure group communication systems (GCSs) in mobile ad hoc networks that employ intrusion detection techniques for dealing with insider attacks tightly...

Correctness proof of a database replication protocol under the perspective of the I/O automaton model

Correctness of recent database replication protocols has been justified in a rather informal way focusing only in safety properties and without using any rigorous formalism. Since a database replication protocol must ensure some degree of replica consistency and that transactions follow a given isolation level, previous proofs only focused in these two issues. This paper proposes a formalization using the I/O automaton model, identifying several components in the distributed system that are involved in the replication support (replication protocol, group communication system, database replicas) and specifying clearly their actions in the global replicated system architecture. Then, a general certification-based replication protocol guaranteeing the snapshot isolation level is proven correct. To this end, different safety and liveness properties are identified, checked and proved. Our work shows that some details of the replication protocols that were ignored in previous correctness justifications are indeed needed in order to guarantee our proposed correctness criteria.

An evaluation of the performance impact of generic group communication APIs

This paper presents an evaluation of the performance impact of two generic group communication APIs, namely Hedera and jGCS, over three well-known group communication systems, namely JGroups, Spread and Appia. The evaluation compared the performance of different configurations of the three group communication systems in a local clustered environment, under different message and cluster sizes, both in standalone mode and when used as plug-ins for the two generic APIs. The results show that there are significant differences in the overhead imposed by each generic API with respect to the performance of the three group communication systems, when used in standalone mode, and that those differences are strongly related to variations in message and also to the way the generic APIs and their plug-in mechanisms are implemented. Based on those results, the paper discusses some of the circumstances upon which it would be worth implementing group communication using the investigated systems.

Energy-efficient relaxed rekeying policies for distributed key management in sensor networks

In this paper, we discuss a basic key management protocol to generate and distribute the keys required for a secure group communication system, which also preserves the backward and forward secrecies. We devise a few relaxed policies for rekeying and formulate an enhanced set of protocols for key management. All the communications in the protocols are properly authenticated using Elliptic Curve Digital Signature scheme. The relaxed protocols reduce the number of rekeying to almost 25%, thus saving energy. The security analysis shows that our protocols can withstand several possible security attacks especially the serious one, the node capture attack.

Analysis of Key Management Schemes for Secure Group Communication and Their Classification

Secure Group Communication is very critical for applications like board-meetings, group discussions and teleconferencing. Managing a set of secure group keys and group dynamics are the fundamental building blocks for secure group communication systems. Several group key management techniques have been proposed so far by many researchers. Some schemes are information theoretic and some are complexity theoretic in nature. Users in the secure group may negotiate with each other to derive a common group key or may compute the group key on their own. Some schemes involve a trusted Key Distribution Center (KDC), which generates and distributes initial pieces of information, whereas in other schemes users themselves select their private information. Storage at each user and communication cost among members of the group vary from scheme to scheme. Here, in this paper we discuss some of the key management schemes proposed earlier based on the considerations mentioned above. We also analyze the schemes with respect to storage, communication and computation costs.

A framework of models for QoS-oriented adaptive deployment of multi-layer communication services in group cooperative activities

This paper presents a framework of architecture-centric models to support the automated and adaptive deployment of communication services for QoS-enabled end-to-end group communication systems. The Transport level (TCP, UDP level) and the above messaging Middleware level are considered as the two communication levels targeted by the QoS-driven adaptation process. Application to crisis management systems (CMS) is considered as a case study from the more general domain to which our results apply: cooperative activity support systems. The adaptation rules rely on graph matching and graph rewriting. The adaptation enactment is based on the dynamic composition of micro-protocols at the Transport level and on the dynamic binding of software components and services at the Middleware level. The deployment model is used as a central feature of service provisioning. The influence of the cooperation and the communication contexts is expressed and maintained consistent by automated graph-based model refinement and transformation.

Optimization of Group Key Management Structure with a Client Join-Leave Mechanism

Many group key management schemes that reduce the total communication cost and/or the computational cost imposed on client devices have been proposed. However, optimizations of the key-management structure have not been studied. This paper proposes ways to optimize the key-management structure in a hybrid group key management scheme. The proposed method is able to minimize both the total communication cost and the computational cost imposed on client devices. First, we propose a probabilistic client join/leave model in order to evaluate the communication and computational costs of group key management schemes. This model idealizes client actions generally and considers the existence of the peaks of the joining/leaving frequency. Thus, we can analyze not only the average case scenario but also the worst case scenario using this model. Then, we formalize the total computation cost and the computational cost imposed on client devices in group key management schemes under the model. We present both an average case analysis and a worst case analysis. Finally, we show the parameters that minimize the total communication cost and the computational cost imposed on clients under the model. Our results should be useful in designing a secure group communication system for large and dynamic groups.

Experiences with building an intrusion‐tolerant group communication system

AbstractThere are many group communication systems (GCSs) that provide consistent group membership and reliable, ordered multicast properties in the presence of crash faults. However, relatively few GCS implementations are able to provide these properties in the presence of malicious faults resulting from intrusions. We describe the systematic transformation of a crash‐tolerant GCS, namely C‐Ensemble, into an intrusion‐tolerant GCS, the ITUA GCS. To perform the transformation, we devised intrusion‐tolerant versions of key group communication protocols. We then inserted implementations of the protocols into C‐Ensemble and made significant changes to the rest of the C‐Ensemble protocol stack to make the stack intrusion tolerant. We quantify the cost of providing intrusion‐tolerant group communication in two ways. First, we quantify the implementation effort by presenting a detailed analysis of the amount of change required to the original C‐Ensemble system. In doing so, we provide insight into the choice of building an intrusion‐tolerant GCS from scratch versus building one by leveraging a crash‐tolerant implementation. Second, we quantify the run‐time performance cost of tolerating intrusions by presenting results from an experimental evaluation of the main intrusion‐tolerant microprotocols. The results are analyzed to identify the parts that contribute the most overhead while providing intrusion tolerance during both normal operation and recovery from intrusions. Copyright © 2007 John Wiley & Sons, Ltd.

Algorithms for dynamic multicast key distribution

We study the problem of multicast key distribution for group security. Secure group communication systems typically rely on a group key, which is a secret shared among the members of the group. This key is used to provide privacy by encrypting all group communications. Because groups can be large and highly dynamic, it becomes necessary to change the group key in a scalable and secure fashion when members join and leave the group. We present a series of algorithms for solving this problem based on key trees. The algorithms attempt to minimize the worst-case communication cost of updates by maintaining balanced key tree structures. We focus on the trade-off between the communication cost because of the structure of the tree and that due to the overhead of restructuring the tree to maintain its balanced structure. The algorithms are analyzed for worst-case tree structure bounds and evaluated empirically via simulations.

Random walk for self-stabilizing group communication in ad hoc networks

We introduce a self-stabilizing group communication system for ad hoc networks. The system design is based on a mobile agent, collecting and distributing information, during a random walk. Three possible settings for modeling the location of the mobile nodes (processors) in the ad hoc network are presented: slow location change, complete random change, and neighbors with probability. The group membership algorithm is based on a mobile agent collecting and distributing information. The new techniques support group membership and multicast, and also support resource allocation.

GCS-MA: A group communication system for mobile agents

Reliable messaging is a key component necessary for mobile agent systems. Current researches focus on reliable one-to-one message delivery to mobile agents. But how to implement a group communication system for mobile agents remains an open issue, which is a powerful block that facilitates the development of fault-tolerant mobile agent systems. In this paper, we propose a group communication system for mobile agents (GCS-MA), which includes totally ordered multicast and membership management functions. We divide a group of mobile agents into several agent clusters, and each agent cluster consists of all mobile agents residing in the same sub-network and is managed by a special module, named coordinator. Then, all coordinators form a ring-based overlay for interchanging messages between clusters. We present a token-based algorithm, an intra-cluster messaging algorithm and an inter-cluster migration algorithm to achieve atomicity and total ordering properties of multicast messages, by building a membership protocol on top of the clustering and failure detection mechanisms. Performance issues of the proposed system have been analysed through simulations. We also describe the application of the proposed system in the context of the service cooperation middleware (SCM) project.