Paper Index: Ahsan Habib 1. On Detecting Service Violations and Bandwidth Theft in QoS Network Domains 2. A Round Trip Time and Time-out Aware Traffic Conditioner for Differentiated Services Networks 3. Design and Evaluation of an Adaptive Traffic Conditioner for Differentiated Services Networks 4. Detecting Service Violations and DoS Attacks 5. Network Tomography-based Unresponsive Flow Detection and Control 6. Edge to edge Measurement-based Distributed Network Monitoring Yuhui Zhong 7. Authorization based on evidence and trust 8. An Algorithm for Building User-Role Profiles in a Trust Environment 9. Authentication-driven Authorization on Web Access 10. Trustworthiness Based Authorization on WWW 11. Separating Between Trust and Access Control Policies: A necessity for Web Applications Mohamed Hefeeda 12. CollectCast: A Peer-to-Peer Service for Media Streaming 13. A hybrid architecture for cost-effective on-demand media streaming 14. Cost-Profit Analysis of a Peer-to-Peer Media Streaming Architecture 15. On-Demand Media Streaming over the Internet 16. On Peer-to-Peer Media Streaming Anjali and Anu Bhargava 17. Applying Fault-tolerance principles to Security research 18. Sensors and Wireless Communication for Medical Care Yi Lu 19. SAGA: Self-Adjusting Congestion Avoidance Routing Protocol for Ad Hoc Networks 20. Secure Wireless Network with Movable Base Stations 21. Achieving Flexibility and Scalability: A New Architecture for Wireless Network 22. An Architecture for Secure Wireless Networking 23. Hierarchical Structure for Supporting Movable Base Stations in Wireless Networks 24. Study of Distance Vector Routing Protocols for Mobile Ad Hoc Networks Weichao Wang _ 25. Defending against Wormhole Attacks in Mobile Ad Hoc Networks 26. On Security Study of Two Distance-vector Routing Protocols for Mobile Ad Hoc Networks 27. On Vulnerability and Protection of Ad Hoc On-demand Distance Vector Protocol 28. Intruder Identification in Mobile Ad Hoc Networks

Bharat Bhargava 29. Fraud Formalization and Detection 30. E-notebook Middleware for Accountability and Reputation Based Trust in Distributed Data Sharing

Communities 31. Fault-tolerant authentication in mobile computing 32. MPEG Video Encryption in Real-time Using Secret Key Cryptography 33. MEPG Video Encryption Algorithms Florian Baumgartner 34. Quality of Service Management with Active Networks 35. Virtual Routers: A Tool for Emulating IP Routers Xiaoxin Wu 36. A Two-Step Paging Scheme in a Macrocell/Microcell Cellular Network 37. Integrating Heterogeneous Wireless Technologies: A Cellular Aided Mobile Ad hoc Network

(CAMA) 38. Assuring Communications by Balancing Load in Cellular Networks Maleq Khan 39. Self-configuring Node Clusters, Data Aggregation, and Security in Microsensor Networks David Yau 40. Heterogeneous CPU Services Using Differentiated Admission Control Gang Ding 41. Peer-to-peer File-sharing over Mobile Ad hoc Networks 42. Error Resilient Video Transmission over Wireless Networks

On Detecting Service Violations and Bandwidth Theft in QoS Network Domains

(Elsevier Science Journal of Computer Communication, (28), 2003)

Ahsan Habib, Sonia Fahmy, Srinivas R. Avasarala, Venkatesh Prabhakar, Bharat Bhargava

CERIAS and Department of Computer Sciences Purdue University,West Lafayette, IN 47907–1398, USA

Abstract

We design and evaluate a simple and scalable system to verify Quality of Service (QoS) in a differentiated services domain. The system uses a distributed edge-to-edge monitoring approach with measurement agents collecting information about delays, losses and throughput, and reporting to a Service Level Agreement Monitor (SLAM). The SLAM detects potential service violations, bandwidth theft, denial of service attacks, and flags the need to redimension the network domain or limit its users. Measurements may be performed entirely edge-to-edge, or the core routers may participate in logging packet drop information. We compare the core-assisted and edge-to-edge schemes, and we extend network tomography-based loss inference mechanisms to cope with different drop precedences in a QoS network. We also develop a load-based service monitoring scheme which probes the appropriate edge routers for loss and throughput on demand. Simulation results indicate that the system detects attacks with reasonable accuracy, and is useful for damage control in both QoS-enabled and best effort network domains. Keywords: Service Level Agreements, Network Tomography, Network Monitoring, Network Security, Quality of Service.

A Round Trip Time and Time-out Aware Traffic Conditioner for Differentiated Services Networks

Proceedings of IEEE ICC (Symposium on Communications QoS and Reliability), 2002

Ahsan Habib, Bharat Bhargava, Sonia Fahmy CERIAS and Department of Computer Sciences

Purdue University,West Lafayette, IN 47907-1398, USA

Abstract TCP connection throughput is inversely proportional to the connection Round Trip Time (RTT). To mitigate TCP bias to short RTT connections, a differentiated services traffic conditioner can ensure connections with long RTTs do not starve when connections with short RTTs get all extra resources after achieving the target rates. Current proposals for RTT-aware conditioners work well for a small number of connections when most TCP connections are in the congestion avoidance phase. If there are a large number of TCP connections, however, connections time-out and go to slow start. We show that current RTT-aware conditioners over-protect long RTT flows and starve short RTT flows in this case. We design and evaluate a conditioner based on RTT as well as the Retransmission Time-out (RTO). The proposed RTT-RTO aware traffic conditioner works well for realistic situations with a large number of connections. Simulation results in a variety of situations confirm that the conditioner mitigates RTT bias. Keywords: Traffic Conditioner, RTT, RTO, Quality of Service, Differentiated Services, Assured Forwarding.

Design and Evaluation of an Adaptive Traffic Conditioner for Differentiated Services Networks

in Proceedings of IEEE International Conference on Computer Communications and Networks (IC3N), 2002

Ahsan Habib, Sonia Fahmy, Bharat Bhargava

CERIAS and Department of Computer Sciences Purdue University,West Lafayette, IN 47907-1398, USA

Abstract

We design and evaluate an adaptive traffic conditioner to improve application performance over the differentiated services assured forwarding behavior. The conditioner is adaptive because the marking algorithm changes based upon the current number of flows traversing through an edge router. If there are a small number of flows, the conditioner maintains and uses state information to intelligently protect critical TCP packets. On the other hand, if there are many flows going through the edge router, the conditioner only uses flow characteristics as indicated in the TCP packet headers to mark without requiring per flow state. Simulation results indicate that this adaptive conditioner improves throughput of data extensive applications like large FTP transfers, and achieves low packet delays and response times for Telnet and WWW traffic.

Detecting Service Violations and DoS Attacks (in Proceedings of NDSS 03)

Ahsan Habib, Mohamed M. Hefeeda, and Bharat K. Bhargava CERIAS and Department of Computer Sciences

Purdue University, West Lafayette, IN 47907 fhabib, mhefeeda, bbg@cs.purdue.edu

Abstract

Denial of Service (DoS) attacks are a serious threat for the Internet. DoS attacks

can consume memory, CPU, and network resources and damage or shut down the operation of the resource under attack (victim). The quality of service (QoS) enabled networks, which offer different levels of service, are vulnerable to QoS attacks as well as DoS attacks. The aim of a QoS attack is to steal network resources, e.g., bandwidth, or to degrade the service perceived by users. We present a classification and a brief explanation of the approaches used to deal with the DoS and QoS attacks. Furthermore, we propose network monitoring techniques to detect service violations and to infer DoS attacks. Finally, a quantitative comparison among all schemes is conducted, in which, we highlight the merits of each scheme and estimate the overhead (both processing and communication) introduced by it. The comparison provides guidelines for selecting the appropriate scheme, or a combination of schemes, based on the requirements and how much overhead can be tolerated.

Network Tomography-based Unresponsive Flow Detection and Control (Proceedings of FTDCS 2003, San Juan, Puerto Rico, May 2003)

Ahsan Habib, Bharat Bhargava

Center for Education and Research in Information Assurance and Security (CERIAS)

and Department of Computer Sciences, Purdue University, West Lafayette, IN 47907-1398

Abstract

To avoid a congestion collapse, network flows should adjust their sending rates.

Adaptive flows adjust the rate, while unresponsive flows do not respond to congestion and keep sending packets. Unresponsive flows waste resources by taking their share of the upstream links of a domain and dropping packets later when the downstream links are congested. We use network tomography---an edge-to-edge mechanism to infer per-link internal characteristics of a domain---to identify unresponsive flows that cause packet drops in other flows. We have designed an algorithm to dynamically regulate unresponsive flows. The congestion control algorithm is evaluated using both adaptive and unresponsive flows, with sending rates as high as four times of the allowable rate of a user, and in presence of short and long-lived background traffic.

Edge-to-edge measurement-based distributed network monitoring Ahsan Habib, Maleq Khan, Bharat Bhargava

( Elsevier Journal of Computer Networks, (44), 2204 )

Abstract

Continuous monitoring of a network domain poses several challenges. First, routers of a network domain need to be polled periodically to collect statistics about delay, loss, and bandwidth. Second, this huge amount of data has to be mined to obtain useful monitoring information. This increases the overhead for high speed core routers, and restricts the monitoring process from scaling to a large number of flows. To achieve scalability, polling and measurements that involve core routers should be avoided. We design and evaluate a distributed monitoring scheme that uses only edge-to-edge measurements, and scales well to large network domains. In our scheme, all edge routers form an overlay network with their neighboring edge routers. The network is probed intelligently from nodes in the overlay to detect congestion in both directions of a link. The proposed scheme involves only edge routers, and requires significantly fewer number of probes than existing monitoring schemes. Through analytic study and a series of experiments, we show that the proposed scheme can effectively identify the congested links. The congested links are used to capture the misbehaving flows that are violating their service level agreements, or attacking the domain by injecting excessive traffic.

Authorization based on evidence and trust In Proceedings of Data Warehouse and Knowledge Management Conference

(DaWak)-2002

Yuhui Zhong Bharat Bhargava CERIAS and Department of Computer Science

Purdue University West Lafayette, IN, U.S.A.

Abstract

Developing authorization mechanisms for secure information access by a large community of users in an open environment is challenging. Current research efforts grant privilege to a user based on his/her properties that are demonstrated by digital credentials (evidences). Holding credentials does not necessarily certify that the user is trustworthy. We use trust to characterize the possibility that a user will not carry out harmful actions. Authorization based on trust as well as evidence makes access control adaptable to users’ behaviors. The research requires: a suitable authorization mechanism that can incorporate the evidence and the trust, appropriate representations of evidence and trust so that their manipulation can be automated. In this paper, we present a trust-enhanced role-mapping server, which can cooperate with RBAC (Role-Base Access Control) mechanisms for authorization based on evidence and trust. The effort of formalizing trust and evidence is discussed.

An Algorithm for Building User-Role Profiles in a Trust Environment In Proceedings of Data Warehouse and Knowledge Management Conference

(DaWak)-2002

Evimaria Terzi, Yuhui Zhong, Bharat Bhargava, Pankaj, Sanjay Madria CERIAS and Department of Computer Sciences,

Purdue University, West Lafayette, IN-47907, USA

Abstract.

A good direction towards building secure systems that operate efficiently in large-

scale environments (like the World Wide Web) is the deployment of Role Based Access Control Methods (RBAC). RBAC architectures do not deal with each user separately, but with discrete roles that users can acquire in the system. The goal of this paper is to present a classification algorithm that during its training phase, classifies roles of the users in clusters. The behavior of each user that enters the system holding a specific role is traced via audit trails and any misbehavior is detected and reported (classification phase). This algorithm will be incorporated in the Role Server architecture, currently under development, enhancing its ability to dynamically adjust the amount of trust of each user and update the corresponding role assignments.

Authentication-driven Authorization on Web Access (in Proceedings of IC 2001)

Yuhui Zhong Bharat Bhargava

CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN 47907

Abstract:

Unlike in traditional computing environments such as operating systems or

databases, the authorized user set, the mode of access, users' access rights, etc., are not predefined in WWW. In order to assign privileges to authorized but not predefined users in dynamic access environments, we propose an approach called authentication-driven authorization. In this approach, authentication is integrated with authorization. The validity of a user is checked by using authentication routines associated with the requested data object. The access permission is achieved by authentication rather than by inheriting from group/role membership relation. A logic-based authorization language has been designed. A prototype has been implemented, which can be used to enforce complex web-based application security policies.

Trustworthiness Based Authorization on WWW (IEEE Workshop on Security in Distributed Data Warehousing,

New Orleans, 2001)

Y. Zhong B. Bhargava M. Mahoui CERIAS and

Department of Computer Sciences Purdue University

West Lafayette, IN 47907

Abstract Current approaches for authorization on Web servers are mostly based on a

predefined set of users or domains. They are not suitable for Internet Web sites where the user set is unbounded and authorized users can be non-predefined. We propose an authorization approach that applies Role-based access control (RBAC) to WWW. Under this approach, system administrators predefine roles, role-permission relations and the policies that assign roles to users (user-role assignment policy). The system automatically collects trustworthy information (valid evidence) and assigns roles to Internet users according to user-role assignment policies. Trustworthiness information plays an important role in user-role assignment. The validity of evidence is assessed based on the trustworthiness information of the evidence provider. In addition, system administrators can specify the trustworthiness constraints that users have to satisfy for holding roles. In this paper, the schema of using RBAC on the Web and the procedure of user-role assignment are presented. The classification and evaluation of trustworthiness are discussed.

Separating Between Trust and Access Control Policies: A necessity for Web Applications

(IEEE Workshop on Security in Distributed Data Warehousing, New Orleans, 2001)

M. Mahoui B. Bhargava Y. Zhong

CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN 47907

Abstract

As Security is the key of success for Web Applications most of the efforts that

have been put in this domain have focused on wining users' trust to adopt the Web environment for their business operations. Although user trust is of paramount importance for Web applications, one also needs to consider Web applications trust towards users here after referred to as user trustworthiness. This paper explains why management of trust/mistrust is an increasing security issue in Web environment and proposes an authorization architecture framework that clearly separates between access control policies and mistrust management. It also describes a model that evaluates trustworthiness of users trust towards its integration in the authorization process.

CollectCast: A Peer-to-Peer Service for Media Streaming

Mohamed Hefeeda, Ahsan Habib, Dongyan Xu, Bharat Bhargava, Boyan Botev (Submitted to ACM/Springer Multimedia Systems Journal)

Abstract

We present the design, implementation, and evaluation of a novel P2P service called CollectCast. CollectCast operates entirely at the application level but infers and exploits properties of the underlying network. The major properties of CollectCast include the following: (1) it infers and leverages the underlying network topology and performance information for the selection of senders; (2) it monitors the status of peers and connections and reacts to peer/connection failure or degradation with low overhead; (3) it dynamically switches active senders and standby senders, so that the collective network performance out of the active senders remains satisfactory. We perform both real-world measurements and simulations of CollectCast. Our simulation results show that CollectCast-based P2P streaming achieves better performance than P2P streaming based only on end-to-end network performance information. The real-world measurements are obtained by implementing a P2P media streaming system (called PROMISE) on top of CollectCast. We have installed and tested PROMISE on the PlanetLab test bed. The results of the packet-level and frame-level performance obtained from streaming several MPEG-4 movies demonstrate the potential benefits for the applications built on top of CollectCast.

A hybrid architecture for cost-effective on-demand media streaming

( Journal of Computer Networks, (44), 2004 )

Mohamed M. Hefeeda, Bharat K. Bhargava, and David K. Y. Yau CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN 47907

Abstract

We propose a new architecture for on-demand media streaming centered around the peer-to-peer (P2P) paradigm. The key idea of the architecture is that peers share some of their resources with the system. As peers contribute resources to the system, the overall system capacity increases and more clients can be served. The proposed architecture employs several novel techniques to: (1) use the often-underutilized peers’ resources, which make the proposed architecture both deployable and cost-effective, (2) aggregate contributions from multiple peers to serve a requesting peer so that supplying peers are not overloaded, (3) make a good use of peer heterogeneity by assigning relatively more work to the powerful peers, and (4) organize peers in a network-aware fashion, such that nearby peers are grouped into a logical entity called a cluster. The network-aware peer organization is validated by statistics collected and analyzed from real Internet data. The main benefit of the network-aware peer organization is that it allows to develop efficient searching (to locate nearby suppliers) and dispersion (to disseminate new .les into the system) algorithms. We present network-aware searching and dispersion algorithms that result in: (i) fast dissemination of new media files, (ii) reduction of the load on the underlying network, and (iii) better streaming service. We demonstrate the potential of the proposed architecture for a large-scale on-demand media streaming service through an extensive simulation study on large, Internet-like, topologies. Starting with a limited streaming capacity (hence, low cost), the simulation shows that the capacity rapidly increases and many clients can be served. This occurs for all studied arrival patterns, including constant rate arrivals, .ash crowd arrivals, and Poisson arrivals. Furthermore, the simulation shows that a reasonable client-side initial buffering of 10–20 s is sufficient to ensure full quality playback even in the presence of peer failures. Keywords: Media streaming, Peer-to-peer systems

Cost-Profit Analysis of a Peer-to-Peer Media Streaming Architecture

(Submit for review)

Mohamed M. Hefeeda, Ahsan Habib, and Bharat K. Bhargava CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN 47907

_ mhefeeda, habib, bb@cs.purdue.edu

Abstract

We study the economic aspects of P2P systems. We present a cost-profit analysis of a media streaming service deployed over a peer-to-peer (P2P) infrastructure. We consider the limited capacity as well as the heterogeneity of peers in the analysis. The analysis shows that with the appropriate incentives for participating peers, the service provider achieves more profit. In addition, the analysis shows how the service provider can maximize its revenue by controlling the amount of incentives offered to peers. By comparing the economics of P2P and conventional client/server media streaming architectures, we show that with a relatively small initial investment, the P2P architecture can realize a large-scale media streaming service.

On-Demand Media Streaming over the Internet (in FTDCS 03)

Mohamed M. Hefeeda and Bharat K. Bhargava CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN 47907

fmhefeeda, bb@cs.purdue.edu

Abstract

We propose a new model for on-demand media streaming centered around the

peer-to-peer (P2P) paradigm. The proposed P2P model can support a large number of clients with a low overall system cost. The P2P model allows for peers to share some of their resources with the system and in return, they get some incentives or rewards. We describe how to realize (or deploy) the proposed model. In addition, we present a new dispersion algorithm (for disseminating the media files into the system) and a searching algorithm (for locating peers with the required objects).

We demonstrate the potential of the P2P model as an infrastructure for a large-scale on-demand media streaming service through an extensive simulation study on large, Internet-like, topologies. Starting with a limited streaming capacity (hence, low cost), the simulation shows that the capacity is rapidly increased and many clients can be served even if they come according to different arrival patterns such as constant rate arrivals, flash crowd arrivals, and Poisson arrivals.

On Peer-to-Peer Media Streaming (Proceedings of IEEE ICDCS'02, Vienna, Austria, July 2002)

D. Xu, M. Hefeeda, S. Hambrush, B. Bhargava CERIAS and Department of Computer Sciences

Purdue University,West Lafayette, IN 47907-1398, USA

In this paper, we study a peer-to-peer media streaming system with the following characteristics: (1) its streaming capacity grows dynamically; (2) peers do not exhibit server-like behavior; (3) peers are heterogeneous in their band-width contribution; and (4) each streaming session may involve multiple supplying peers. Based on these characteristics, we investigate two problems: (1) how to assign media data to multiple supplying peers in one streaming session and (2) how to fast amplify the system s total streaming capacity. Our solution to the first problem is an optimal media data assignment algorithm OTSp2p, which results in minimum buffering delay in the consequent streaming session. Our solution to the second problem is a distributed differentiated admission control protocol DACp2p. By differentiating between requesting peers with different out-bound bandwidth, DACp2p achieves fast system capacity amplification; benefits all requesting peers in admission rate, waiting time, and buffering delay; and creates an incentive for peers to offer their truly available out-bound bandwidth.

Applying Fault-tolerance principles to Security research (in Proceedings of IEEE Symposium on "Reliable Distributed System" 2001. )

Anjali Bhargava Bharat Bhargava TRW, Redonodo Beach CA 90278 CERIAS and CS Dept bhargava_anjali@hotmail.com Purdue University bb@cs.purdue.edu

Sensors and Wireless Communication for Medical Care

Anu Bhargava and Mike Zoltowski

(in Proceedings of DEXA, 2003)

Abstract Biological, chemical, and radiological agents can tamper with the activities of medical

care providers, patient samples, and medicine administration. This results in a shut down of all medical care, leaving patients at a major risk. The technical challenge is to develop sensors to detect and monitor any violations in the medical care environment before threat to life occurs. Wireless devices must communicate multimedia data such as patient information, laboratory results, prescriptions, and X-ray and EKG reports. The reliability, security, and accuracy of these sensors and wireless devices can affect the timeliness access to information for patient monitoring. In addition, data can be corrupted, computer information systems can fail, and communication networks may experience denial of service attacks leading to complete failure of proper patient care. In this paper, we discuss security and safety issues in medical environment, the technology, types, and characteristics of sensors, and research issues in smart antennas, denial of service, fault tolerant authentication, privacy issues, and energy considerations. A discussion of sensors in patient rooms, clinics/wards, hospitals, and measurements of safety and security is presented. The available devices for sensor and wireless communication are also briefly included.

SAGA: Self-Adjusting Congestion Avoidance Routing Protocol for Ad Hoc Networks

Yi Lu, Bharat Bhargava

(Submitted to TMC)

Abstract Congestion in ad hoc networks is a serious problem. Contention among neighbors for the access to the shared media is the primary cause for the network congestion. The objective of this research is to bring the consideration of congestion into the design of the routing protocols. The main thrust is to avoid congestion by minimizing contentions for channel access. The intermediate delay (IMD) is proposed as a routing metric. It enables routing protocols to select routes that bypass mobile nodes in contention. IMD characterizes the impacts of channel contention, traffic load, and the length of a route. The packet transmission procedure of the distributed coordination function (DCF) in the IEEE 802.11 standard is analyzed and used as a study case for evaluation and experimentation. An estimate of the transmission delay is derived based on local information available at a node. The estimation takes the impact of active traffic in the neighborhood into account without exchanging messages with neighbors. The self-adjusting congestion avoidance (SAGA) routing protocol is designed with IMD as the routing metric. The performance of SAGA is evaluated and compared with that of ad hoc on-demand distance vector (AODV), dynamic source routing (DSR), and destination-sequenced distance-vector (DSDV) protocols using simulation. Two types of traffic are considered: constant bit rate traffic and traffic exhibiting long range dependency. SAGA can sustain heavier traffic load and offers higher peak throughput than AODV and DSR. The overhead of SAGA can be as low as 10% as that of AODV and 12% as that of DSR. The average end-to-end delay of SAGA is the lowest among the protocols. It is shown that considerations of congestion and intermediate delay instead of hop count can enhance routing performance significantly.

Secure Wireless Network with Movable Base Stations

Y. Lu, B. Bhargava, W. Wang, Y. Zhong, and X. Wu,

(IEICE Transaction on Communications, IEICE/IEEE Joint Special Issue on Assurance Systems and Networks, Vol.E86-B, 2003)

Abstract

Security, flexibility, and scalability are critical to the success of wireless communications. Wireless networks with movable base stations combine the advantages of mobile ad hoc networks and wireless LAN to achieve these goals. Hierarchical mobile wireless network (HMWN) is proposed for supporting movable base stations. In such a system, mobile hosts are organized into hierarchical groups. The group agents serve as a distributed trust entity. A secure packet forwarding algorithm and an authentication and key exchange protocol are developed to protect the network infrastructure. A roaming support mechanism and the associated mutual authentication protocol are proposed to secure the foreign group and the mobile host when it roams within the network. The computation overhead of secure packet forwarding and roaming support algorithms is studied via experiments. The results demonstrate that these two security mechanisms only require, respectively, less than 2% and 0.2% to 5% CPU time in a low-end 700MHz PC.

Achieving Flexibility and Scalability: A New Architecture for Wireless

Network (in Proceedings of IC'2001)

Yi Lu Bharat Bhargava

CERIAS and Department of Computer Sciences Purdue University

West Lafayette, IN, U.S.A

Abstract We present a Hierarchical Hybrid Network architecture for wireless networks. In such a network, mobile nodes are hierarchically organized into groups. Different groups can have different routing protocols. Mobile nodes communicate with nodes outside their groups through the group agents. The groups are highly autonomous. This architecture is flexible and scalable. We conduct experiments to compare the new architecture with Ad Hoc networks. The new architecture has a more stable topology and higher throughput when the number of mobile nodes is large. The objective of our research is to set up a survivable, secure mobile wireless network. Keywords: wireless, mobile, Ad Hoc, hierarchical

An Architecture for Secure Wireless Networking

Published in IEEE workshop on Reliable and Secure Application in Mobile Environment, New Orleans, Oct. 2001.

Yi Lu Bharat Bhargava Mohamed Hefeeda

Center For Education and Research in Information Assurance and Security and

Department of Computer Sciences Purdue University

West Lafayette, IN, U.S.A.

Abstract

As wireless networks are rapidly deployed, the security of wireless environments will be mandatory. Considering the inherent security limitations of Ad Hoc networks, we propose a new architecture: Hierarchical Hybrid networks for secure wireless networking. In such a network, wireless nodes are organized into groups. We present a secure communication scheme to defend against link attacks. Secure mobility support for mobile hosts roaming among groups is also discussed. Mutual authentication is used to protect both foreign groups and mobile hosts. We propose a fault-tolerant authentication scheme to make systems survivable from agent failures. These security schemes take into account the characteristics of wireless networks.

Hierarchical Structure for Supporting Movable Base Stations in Wireless Networks

To appear in International Conference on Telecommunications (ICT'2003)

Yi Lu Weichao Wang Bharat Bhargava

Center For Education and Research in Information Assurance and Security and

Department of Computer Sciences Purdue University

West Lafayette, IN, U.S.A.

Abstract

Wireless networks with movable base stations combine the advantages of mobile ad hoc networks and wireless LAN to achieve both flexibility and scalability. We present the hierarchical mobile wireless network (HMWN) to support movable base stations. HMWN may be applied to ad hoc networks as well to build a virtual hierarchy. In such a system, mobile hosts are organized into hierarchical groups. Four basic operations for setting up and maintaining the network structure are grouping, registration, leaving, and migration. An efficient group membership management protocol is developed to support mobile hosts roaming among different groups. The segmented membership-based group routing (SMGR) protocol is proposed to take advantage of the hierarchical structure and membership information. In this protocol, only local message exchanging is required for maintaining network topology and routing information. Simulation-based experiment demonstrates the scalability of the design in terms of protocol overheads.

Study of Distance Vector Routing Protocols for Mobile Ad Hoc Networks

To appear in the proceedings of IEEE PerCom, 2003

Yi Lu, Weichao Wang, Yuhui Zhong and Bharat Bhargava CERIAS and

Department of Computer Sciences Purdue University

West Lafayette, IN, 47907, USA yilu, wangwc, zhong, bb@cs.purdue.edu

Abstract

We investigate via simulation the performance issues of Destination-Sequenced Distance Vector (DSDV) and Ad-hoc On-demand Distance Vector (AODV) routing protocols for mobile ad hoc networks. Four performance metrics are measured by varying the maximum speed of mobile hosts, the number of connections, and the network size. The relationship between network topology changes and mobility is investigated by using linear regression analysis. The simulation results indicate that AODV outperforms DSDV in less stressful situations, while DSDV is more scalable with respect to the network size and traffic load. It is observed that network congestion results in more than half of the dropped packets for both protocols. Our observation indicates that always sending packets through the shortest routes might cause congestion in sparse networks, but rarely in dense ones. We propose a new routing protocol, called congestion aware distance vector (CADV). CADV outperforms AODV in packet delivery ratio by about 5%, while introduces less protocol load than AODV does. The result demonstrates that the performance of proactive routing protocols can be improved by integrating with congestion avoidance mechanisms even in less stressful situations. Index Terms: ad hoc networks, distance vector, routing protocol, performance, congestion aware

Fraud Formalization and Detection Bharat Bhargava, Yuhui Zhong, Yuhua Lu

(in the proceedings of DaWak 2003)

Abstract A fraudster can be an impersonator or a swindler. An impersonator is an illegitimate user who steals resources from the victims by “taking over” their accounts. A swindler is a legitimate user who intentionally harms the system or other users by deception. Previous research efforts in fraud detection concentrate on identifying frauds caused by impersonators. Detecting frauds conducted by swindlers is a challenging issue. In this paper, three types of deceiving intentions, namely uncovered deceiving, intention, trapping intention, and illusive intention, are defined. We propose an architecture that integrates deceiving intention prediction with fraud detection to catch swindlers. It consists of four components: profile-based anomaly detector, state transition analysis, deceiving intention predictor, and decision-making component. Profile-based anomaly detector outputs fraud confidence indicating the possibility of fraud when there is a sharp deviation from usual patterns. State transition analysis provides state description to users when an activity results in entering a danger state leading to fraud. Deceiving intention predictor discovers malicious intentions. DI-confidence is used to characterize the belief that a target entity has such intentions. An algorithm is developed to evaluate DI-confidence by analyzing an entity’s behaviors. Its effectiveness is investigated via experimental study. A user-configurable risk evaluation function is designed for decision-making component. The decision-making component raises a fraud alarm when expected risk is greater than fraud-investigating cost.

E-notebook Middleware for Accountability and Reputation Based Trust in Distributed Data Sharing Communities

Paul Rut, Dongyan Xu, Bharat Bhargava and Fred Regnier (accepted to appear in iTrust 2004)

Abstract This paper presents the design of a new middleware which provides support for trust and accountability in distributed data sharing communities. One application is in the context of scientific collaborations. Multiple researchers share individually collected data, who in turn create new data sets by performing transformations on existing shared data sets. In data sharing communities building trust for the data obtained from others is crucial. However, the field of data provenance does not consider malicious or untrustworthy users. By adding accountability to the provenance of each data set, this middleware ensures data integrity insofar as any errors can be identified and corrected. The user is further protected from faulty data by a trust view created from past experiences and second-hand recommendations. A trust view is based on real world social interactions and reflects each user's own experiences within the community. By identifying the providers of faulty data and removing them from a trust view, the integrity of all data is enhanced.

Fault-tolerant authentication in mobile computing (in International Conference on Internet Computing (LC 2000))

B. Bhargava, S. Kamisetty S. Madria

CERIAS and Department of Computer Sciences Purdue University

West Lafayette, IN, U.S.A

Abstract Survivability and secure communications are essential in a mobile computing environment. In a secure network, all the hosts must be authenticated before communicating, and failure of the agents that authenticate the hosts may completely detach the hosts from the rest of the network. In this paper, we describe two techniques to eliminate such a single point of failure. Both of these approaches make use of backup servers, but they differ in the way they are organized and deployed. We evaluate our proposed architectures with a prototype system that we built. We also identify various security threats and performance issues in group (multicast) communications in mobile computing environments. We propose a scheme for efficient key distribution and management using key graphs to provide secure multicast service.

MPEG Video Encryption in Real-time Using Secret Key Cryptography

(In Proceedings of the 6th ACM International Multimedia Conference, 1998)

C. Shi, S. Wang Bharat Bhargava CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN, U.S.A

Abstract

We present a fast MPEG video encryption algorithm called RVEA which encrypts selected sign bits of the DCT coefficients and motion vectors using secret key cryptography algorithms such as DES or IDEA. RVEA features bounded computation time for any size of video frame and is robust to both plaintext and cipher text attack. Since it adds a very small overhead to the MPEG video compression process, a software implementation is fast enough to meet the real-time requirement of MPEG video applications.

Defending against Wormhole Attacks in Mobile Ad Hoc Networks Weichao Wang, Bharat Bhargava, Yi Lu, Xiaoxin Wu

(Submitted to Wiley WCMC)

Abstract In ad hoc networks, malicious nodes can carry wormhole attacks by eavesdropping packets, tunneling them to another location in the network, and retransmitting them. The attacks fabricate a false scenario on neighbor relations among mobile nodes. The attacks threaten the safety of ad hoc routing protocols and some security enhancements. We propose a classification of the attacks that establishes a basis on which the detection capability of the approaches can be identified. The previous approaches adopt the mechanisms including Packet Leashes, accurately synchronized clocks, and directional antennas. They focus on the prevention of wormholes between neighbors that trust each other. As a more generic approach, we propose the design of an end-to-end mechanism that can detect wormholes on a multi-hop route. The mechanism will adopt geographic information. To reduce the computation and storage overhead, a suite of schemes will be designed to manage the information. The mobile nodes can achieve different tradeoffs between the overhead and the detection capability by adjusting a group of parameters. The schemes to control communication overhead will also be studied. The practicability of the proposed mechanism will be examined through simulations and experiments on real devices. As a security enhancement, the mechanism is able to be combined with existing routing protocols to defend against wormhole attacks.

On Security Study of Two Distance-vector Routing Protocols for Mobile Ad Hoc Networks

in the proceedings of IEEE PerCom, 2003

Weichao Wang, Yi Lu, Bharat K. Bhargava CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN 47907

wangwc, yilu, bb @cs.purdue.edu

Abstract This paper compares the security properties of Ad Hoc On-demand Distance Vector (AODV) and Destination Sequence Distance Vector (DSDV) protocols, especially the difference caused by on-demand and proactive route queries. The on-demand route query enables the malicious host to conduct real time attacks on AODV. The communication overhead of attacks on DSDV is independent of the attack methods and the width of attack targets. A single false route propagates slower in AODV than in DSDV. The detection of false destination sequence in AODV heavily depends on the mobility of hosts. False distance vector and false destination sequence attacks are studied by simulation. The delivery ratio, communication overhead, and the propagation of false routes are measured by varying the traffic load and the maximum speed of host movement. The anomalous patterns of sequence numbers detected by destination hosts can be applied to detect the false destination sequence attacks.

Intruder Identification in Mobile Ad Hoc Networks (Technical Report of Department of Computer Sciences, 2002)

Weichao Wang, Yi Lu, Bharat K. Bhargava

CERIAS and Department of Computer Sciences Purdue University

West Lafayette, IN 47907, USA

Abstract Intruder identification in ad hoc networks is complementary to intrusion detection. Its research challenge is to correctly identify the malicious hosts in a flat infrastructure. We propose a specification of intruder identification and the criteria to evaluate the algorithms. Specifically, we consider intruder identification in the AODV (Ad hoc On-demand Distance Vector) protocol. We study the attacks on AODV that target its security flaws. A protocol called RLR (Reverse Labeling Restriction) is presented to identify and isolate malicious hosts in ad hoc networks using AODV. RLR traces back the propagation paths of false routing information through reverse labeling. It enables the hosts to share their knowledge about the sources of attacks in a secure way. The mobile hosts reach consistent conclusions on malicious hosts by combining local decisions with global agreements. We simulate RLR using ns2. The simulation results show that up to 95% of the normal hosts can successfully identify all attackers. Isolating the malicious hosts through rejecting routing information from them causes a 30% increase in the data delivery ratio. Two parameters, namely, host mobility and the number of independent malicious hosts, are selected to study the effectiveness, accuracy, and overhead of RLR in different network environments. The robustness analysis shows that RLR does not introduce any new vulnerabilities. We believe that RLR can be easily ported to other ad hoc network routing protocols.

On Vulnerability and Protection of Ad Hoc On-demand Distance Vector Protocol

in International Conference on Telecommunications (ICT'2003)

Weichao Wang, Yi Lu, Bharat K. Bhargava CERIAS and Department of Computer Sciences

Purdue University West Lafayette, IN 47907, USA

wangwc, yilu, bb @cs.purdue.edu

Abstract Vulnerabilities and the attacks on Ad Hoc On demand Distance Vector (AODV)

protocol are investigated and studied via analysis and simulation. The attacks are classified by their target properties. The analysis shows that the on demand route query enables the malicious host to conduct real time attacks on AODV. False distance vector and false destination sequence attacks are studied by simulation. Two connection scenarios: common destination and uniformly distributed traffic load are considered. The delivery ratio, attack overhead, and the propagation of false routes are measured by varying the number of connections and the mobility of the hosts. The simulation results illustrate that the attacker can confuse the network connectivity with false routes and lead to a decrease up to 75% in the delivery ratio. When the hosts are uniformly distributed, the false distance vector attacks can not cheat more than half of the hosts. But the false destination sequence routes can propagate to most of the network. The anomaly patterns of sequence numbers carried by routing request (RREQ) can be applied to detect the false destination sequence attacks. The vulnerability analysis results and anomaly patterns can be employed by other Ad Hoc routing protocols to establish intrusion prevention and detection mechanisms.

Index Terms—Ad Hoc Networks, AODV, Vulnerability, Intrusion Detection.

MEPG Video Encryption Algorithms in Multimedia Tools and Applications

Bharat Bhargava, Changgui Shi and Sheng-Yih Wang

Abstract

Multimedia data security is important for multimedia commerce. Previous cryptography studies have focused on text data. The encryption algorithms developed to secure text data may not be suitable to multimedia applications because of large data sizes and real time constraint. For multimedia applications, light weight encryption algorithms are attractive. In this paper, we present four fast MPEG video encryption algorithms. These algorithms use a secret key randomly changing the sign bits of DCT coefficients and/or the sign bits of motion vectors. The encryption effects are achieved by the IDCT during MPEG video decompression processing. These algorithms add very small overhead to MPEG codec. Software implementations are fast enough to meet the real time requirement of MPEG video applications. Our experimental results show that these algorithms can achieve satisfactory results. We believe that they can be used to secure video-on-demand, video conferencing and video email applications.

Quality of Service Management with Active Networks Florian Baumgartner, Torsten Braun, Bharat Bhargava

Institute of CS and AM Department of CS University of Bern, Switzerland Purdue University

Abstract

Active Networks can provide lightweight solutions for network management related tasks. Specific requirements for these tasks have to be met, while at the same time several issues crucial for active networks can be solved rather easily. A system addressing especially network management was developed and implemented. It provides a flexible environment using the platform independent programming language Python, and also supports platform dependent native code. By allowing to add new functions to network devices it improves the performance of Internet routers, and simplifies the introduction and maintenance of new services.

To show the capabilities of the approach, a set of different quality of service related applications, like a smart dropping scheme and a simple multicast mechanism, have been implemented. The evaluation of these services shows the advantages of the architecture, and the benefits for the task of network and quality of service management.

Virtual Routers: A Tool for Emulating IP Routers Florian Baumgartner, Torsten Braun, Bharat Bhargava

Institute of CS and AM Department of CS University of Bern, Switzerland Purdue University

Abstract

For the development of communication services the set up of experimental networks with a sufficient size is a crucial element. Unfortunately the availability of the required equipment like routers and hosts is very limited and cost intensive. On the other hand simulations often lack interoperability to real systems and scalability. This paper presents an approach between these two alternatives and allows the set up of test beds on a cluster of computers with full interoperability to the real world.

A Two-Step Paging Scheme in a Macrocell/Microcell Cellular Network

(submiited to IEEE Transactions on Vehicular Technology) Xiaoxin Wu and Bharat Bhargava CS department, Purdue University West Lafayette, IN47906 {wu,bb}@cs.purdue.edu Biswanath Mukherjee CS Department, UC Davis Davis, CA95616 mukherje@cs.purdue.edu Abstract In a cellular network, a called mobile unit (callee) is found by the method of

paging. Paging is a procedure in which the paging messages are broadcast into the network so that the called mobile unit can receive the paging message and try to communicate with the caller. Location update is needed when a mobile unit changes its location, so it is very useful to find the callee with less paging cost. A lot of research has been done on location update/paging in a single-tier cellular network, but little work has been done in hierarchical networks. In this work, we propose a low-cost, two-step paging scheme in a macrocell/microcell architecture. It has the advantage that a mobile unit in such a cellular network can receive a signal from both a macrocell and a microcell. A callee will be paged in the macrocell tier first. If the paging delay in the macrocell tier is too high because of large queuing delay, the callee will then be paged in the microcell tier. The location update is operated only in the macrocell tier to reduce the operating cost and different paging topologies are used in different tiers. Our analytical results show that, with the low location update/paging cost, the two-step paging scheme also achieves low paging delay.

Integrating Heterogeneous Wireless Technologies: A Cellular Aided Mobile Ad hoc Network (CAMA)

B. Bhargava, X. Wu, Y. Lu and W. Wang

(accepted for publication in ACM Special Issues of the Journal on Special Topics in Mobile Networking and Applicaitons (MONET). )

Abstract

A mobile ad hoc network is a collection of wireless terminals that can be deployed rapidly. Its deficiencies include limited wireless bandwidth efficiency, low throughput, large delays, and weak security. Integrating it with a well-established cellular network can improve communication and security in ad hoc networks, as well as enrich the cellular services. This research proposes a cellular aided mobile ad hoc network (CAMA) architecture, in which a CAMA agent in the cellular network manages the control information, while the data is delivered through the mobile terminals (MTs). The routing and security information is exchanged between MTs and the agent through cellular radio channels. A position-based routing protocol, the multi-selection greedy positioning routing (MSGPR) protocol, is proposed. At times due to the complicated radio environment, the position information is not precise. Even in these cases, the MT can still find its reachable neighbors (the association) by exchanging “hello” messages. This association is used in complement with the position information to make more accurate routing decisions. Simulation results show that the delivery ratio in the ad hoc network is greatly improved with very low cellular overhead. The security issues in the proposed architecture and the corresponding solutions are addressed. The experimental study shows that CAMA is much less vulnerable than a pure ad hoc network.

Assuring Communications by Balancing Load in Cellular Networks

X. Wu, B. Mukherjee, G.-H. Chan and B. Bhargava (IEICE Transaction on Communications, IEICE/IEEE Joint Special Issue on

Assurance Systems and Networks, Vol.E86-B, 2003.)

Abstract In a fixed-channel-allocation (FCA) cellular network, a fixed number of channels are assigned to each cell. However, under this scheme, the channel usage may not be efficient because of the variability in the offered traffic. Different approaches such as channel borrowing (CB) and dynamic channel allocation (DCA) have been proposed to accommodate variable traffic. Our work expands on the CB scheme and proposes a new channel-allocation scheme -- called mobile-assisted connection-admission (MACA) -- to achieve load balancing in a cellular network, so as to assure network communication. In this scheme, some special channels are used to directly connect mobile units from different cells; thus, a mobile unit, which is unable to connect to own base station because it is in a heavily-loaded ``hot'' cell, may be able to get connected to its neighboring lightly-loaded cold cell's base station through a two-hop link. Research results show that MACA can greatly improve the performance of a cellular network by reducing blocking probabilities.

Self-configuring Node Clusters, Data Aggregation, and Security in Microsensor Networks

Maleq Khan, Bharat Bhargava, Sarika Agarwal, Leszek Lilien, and Pankaj

Abstract Microsensors operate under severe energy constraints and should be deployed in

large numbers without any pre-configuration. We construct a generalized self-clustering algorithm, called Low-energy Localized Clustering (LLC). It integrates the ideas of two self-configuring clustering algorithms: the Localized algorithm and the Low Energy Adaptive Clustering Hierarchy algorithm. LLC covers a range of behaviors from the better-clustering performance of the Localized method to the energy-efficient operation of the LEACH method. The main advantage of LLC is that it can be energy-efficient while maintaining localization. Data aggregation techniques such as summarization, finding representative data items, and pattern matching are proposed. Data aggregation is a necessity in microsensor networks, since transmitting huge volumes of raw data is an energy-intensive operation. Finally, security issues are discussed and an energy-efficient Randomized Data Authentication algorithm is designed specifically for microsensor applications.

Heterogeneous CPU Services Using Differentiated Admission Control

D. Yau and B. Bhargava (Journal of Multimedia Tools and Applications, Special Issue on QoS in

Multimedia Networks, Vol. 17, 2002)

Abstract We present an adaptive controlled scheduler for heterogeneous applications running on general purpose computers. Our scheduler can effectively support diverse application requirements. It employs uniform rate-based sharing. Application heterogeneity is satisfied by partitioning CPU capacity into service classes, each with a different criterion for admission control. As a result, we are able to provide at once guaranteed performance, flexible allocation of rates with excellent scalability and intermediate service classes offering tradeoffs between reserved rate utilization and the strength of guarantees. Our scheduler has been implemented in Solaris 2.5.1. It runs existing applications without modifications. We present experimental results showing the scalability, efficiency, guaranteed performance, and overload performance aspects of our scheduler. We demonstrate the importance of priority inheritance implemented in our scheduler for stable system performance.

Peer-to-peer File-sharing over Mobile Ad hoc Networks

G. Ding and B. Bhargava, (in the First International Workshop on Mobile Peer-to-Peer Computing, 2004)

Abstract

Current peer-to-peer file sharing systems mostly work on wired networks. Mobile ad hoc network is characterized as multi-hop wireless communications between mobile devices. In this paper, six routing approaches with different complexity are proposed to enable peer-to-peer file sharing in mobile ad hoc networks. The performance of the proposed approaches is evaluated and compared in terms of scalability, complexity, energy efficiency, mobility, and so on. It is concluded that the cross-layer protocols perform better than simply overlaying peer-to-peer searching protocol on mobile ad hoc networks.

Error Resilient Video Transmission over Wireless Networks

Gang Ding1, Halima Ghafoor2, and Bharat Bhargava1

(in the 6th IEEE International Conf. on Object-oriented Real-time Distributed Computing, 2003)

Abstract

An error resilient architecture for video transmission over mobile wireless networks is presented. Radio link layer, transport layer, and application layer are combined to deal with high error rate in wireless environments. The algorithms for both sender and receiver are given. An adaptive algorithm is presented to automatically adjust parity data length in error control. The performance of the proposed algorithm is analyzed through experimental studies.