2 Computer Science Seminars: Privacy, Social Networks, Trust, and Terrorism | On Modeling, Analysis, and Optimization of Packet Aggregation Systems

25 Jun

Boğaziçi Uni. Department of Computer Engineering, Engineering Building Vedat Yerlici Conference Hall, 29th June 2009, 09:30 ? 12:30

Privacy, Social Networks, Trust, and Terrorism


After a snapshot of the privacy topics likely to attract legislative activity in the new year, we?ll take a look at social networking web sites, where participants often live in a ?panopticon-like? environment, since social networking sites and third party applications on them often have default settings that encourage sharing. However, “The Internet is a cruel historian.” and a professional individual who networks with potential employers generally prefers not to be confused with a person with the same name who is portrayed as a party animal.

If an attacker uses a social networking site to gather enough personal information to make a good guess at a user?s password or other authentication mechanism, he can change the user?s settings and personal history and (allow many others to) track the user?s comings and goings (as well as those of her ?friends?). In one notable demonstration of this, (real) friends even created an account and a persona for a real person, a computer security expert, using information publicly available from the Internet, that was good enough to fool a sister of the victim. An unvetted malicious third party application that a naïve user allows to run with social networking programs could do the same thing. We?ll show some examples of social networking privacy issues.

Various trust-enhancing measures can be used to design privacy into new systems from the start, and we?ll discuss these and a number of guidelines that have been developed and are in use by large software firms to help design products with privacy and security built in, rather than bolted on.

We will conclude by discussing a recent U. S. National Research Council report on privacy in the struggle against terrorists, its framework for program assessment, and its conclusions about privacy, data mining, and related issues.

Lance J. Hoffman
Computer Science Department
The George Washington University
Washington DC 20052

On Modeling, Analysis, and Optimization of Packet Aggregation Systems


In packet communication systems, a header is attached to the transmitted packet at each layer. The overhead due to the transmission of the individual header can have a significant impact on the performance of the communication system especially when the system operates in heavy load. In order to increase data throughput, a number of packets sharing a single header can be aggregated into a frame.

In this paper, we present a mathematical model for a packet aggregation system assuming a general distribution for the packet length. For a given header size, we obtain the minimum system utilization where packet aggregation improves the system performance. We also analyze the asymptotic behavior of such systems leading to a simple heuristic policy on the optimum aggregation level. It is shown that the impact of the variability of the packet length distribution on different system performance measures is rather insignificant when the system load is low or moderate.

We also show that the correlation of the sizes of the successive frames in the aggregation system increases rapidly as the system utilization increases. However, the packet length variability has little impact on the correlation.

Khosrow Sohraby
Dept. of Computer Science and Electrical Engineering
University of Missouri-Kansas City


09:30 ? 10:00 Coffee and Tea
10:00 ? 10:45 Talk by Prof. Hoffman
10:45 ? 11:00 Discussion
11:00 ? 11:15 Coffee Break
11:15 ? 12:00 Talk by Prof. Sohraby
12:00 ? 12:15 Discussion

LCV: Please contact gaye.genc at to confirm your attendance until 10am 26th June 2009, Friday.

Short Bio of Lance J. Hoffman

Distinguished Research Professor
Computer Science Department
The George Washington University

Founder and Senior Staff Researcher,
Cyberspace Security Policy and Research Institute

Dr. Lance J. Hoffman is known for his pioneering research on computer security and risk analysis, and for his interdisciplinary work in computer privacy issues. Distinguished Research Professor of Computer Science at The George Washington University in Washington, D. C. and Founder of the School of Engineering’s Cyberspace Policy Institute (now Cyberspace Security Policy and Research Institute), he is in charge of the computer security and information assurance program in computer science.

Short Bio of Khosrow Sohraby

KHOSROW SOHRABY is currently the Curators’ Professor of Computer Science and Electrial Engineering at the University of Missouri-Kansas City. He received B.Eng and M.Eng degrees from McGill University, Montreal, Canada in 1979 and 1981, respectively, and Ph.D. degree in 1985 from the University of Toronto, Toronto, Canada, all in Electrical Engineering. His current research interests include design and analysis of high speed computer and communications networks, traffic management and analysis, modern queueing theory, large-scale computations in performance analysis, multimedia networks, and networking aspects of wireless and mobile communications. He is an active member of IEEE Communications Society and has served as the guest editor of number of special issues of the Journal of Selected Areas in Communications and Communications Magazine.

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Posted by on June 25, 2009 in Programlama


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