Remote Localization of Mobile Cellular Users from Across the Internet (Sep. 2011 - May 2013)
Network-based remote localization of mobile cellular users and its privacy implications.
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Abstract:
Many third parties desire to discover and disclose your location with the help of your cell phone. Using an embedded GPS, phone software will commonly reveal coordinates to carriers, advertisers, and applications. Can a remote party determine locational information ab- sent explicit GPS information? For example, given a known starting or ending point, can a streaming music server distinguish the path you’ve taken through the physical world? We show that the path a cell phone and its owner take from or to a known location can be determined from remote observations of changes in TCP throughput. Empirically, our method can correctly determine with greater than 72% accuracy the path taken by phone from one of four paths, and with 60% accuracy the path taken from among eight paths.
Measurement and Analysis of Child Pornography Trafficking on P2P Networks (Sep. 2011 - May 2013)
Characterizing trafficking of contraband content on Gnutella and eMule peer-to-peer networks.
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Abstract:
Peer-to-peer networks are the most popular mechanism for the criminal acquisition and distribution of child pornography (CP). In this paper, we examine observations of peers sharing known CP on the Gnutella and eMule networks, which were collected by law enforcement using forensic tools that we developed. We characterize a year’s worth of network activity and evaluate different strategies for prioritizing investigators’ limited resources.
First, we focus on strategies for reducing the number of CP files available on the network by removing a minimal number of peers. We present a metric for peer removal that is more effective than simply selecting peers with the largest libraries or the most days online. We show that any successful strategy must target offenders from all countries. Second, we characterize the aggressiveness of six peer subgroups, including: peers using Tor, peers that bridge multiple p2p networks, and the top 10% of peers contributing to file availability. We find that these subgroups are more aggressive in their trafficking, having more known CP and more uptime, than the average peer. Finally, while in theory Tor presents a challenge to investigators, we observe that in practice offenders use Tor inconsistently. Over 90% of regular Tor users send traffic from a non-Tor IP at least once after first using Tor.
Concurrent Wi-Fi Connections for Highly Mobile Clients (Sep.2009 - Sep. 2011)
Design, implementation, and evaluation of a system that provides for concurrent Wi-Fi connections in highly mobile scenarios where connections are both intermittent and fleeting. Advisors:Mark Corner, Brian Levine, PRISMS Lab, UMass
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Abstract:
We present the first in-depth analysis of the performance of attempting concurrent AP connections from highly mobile clients. Previous solutions for concurrent Wi-Fi are limited to stationary wireless clients and do not take into account a myriad of mobile factors. Through an analytical model, optimization framework, and numerous outdoor experiments, we show that connection duration, AP response times, channel scheduling, available and offered bandwidth, node speed, and DHCP joins all affect performance. Building on these results, we design, implement, and evaluate a system, Spider, that establishes and maintains concurrent connections to 802.11 APs in a mobile environment. The system uses multi-AP selection, channel-based scheduling, and opportunistic scanning to maximize throughput while mitigating the overhead of association and DHCP. While Spider can manage multiple channels, we empirically demonstrate that it achieves maximum throughput when using multiple APs on a single channel. Our evaluation shows that Spider provides a 400% improvement in throughput and 54% improvement in connectivity over stock Wi-Fi implementations.
DOME: Large-scale & Diverse Mobie Wireless Testbed (Sep.2007 - Jan.2012)
Analysis and evaluation of real-world mobile networks through DOME,
a large-scale mobile testbed with temporal, technological, and spatial diversity. Advisors:Mark Corner, Brian Levine, PRISMS Lab, UMass
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Abstract:
Mobile systems and networking researchers confront a myriad of challenges,
including power consumption, channel and radio characteristics, mobility,
and node density. Alone, each of these factors is complex, and their
combination can be unpredictable and hard to model.
These challenges have led to a great deal of mobile research confined to
the world of simulation, producing results with little-to-no real-world validation.
Our Diverse Outdoor Mobile Environment (DOME) has been built in response to these challenges.
DOME consists of 40 computer-equipped buses, numerous battery-powered nomadic nodes, hundreds of organic WiFi access points, and a 26-node municipal WiFi mesh network.
Digital Image Enhancement Using a Vehicular Image Capturing Platform (Jun.2009 - Jan.2011) Advisors:Rui Wang, Brian Levine, Mark Corner, Graphics Group and PRISMS Lab, UMass
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Abstract
In this work, we define the quality transfer problem and present an approach to
tackle it: Given a low-quality image taken from a mobile phone, how could you enhance it in a visually plausible way to include additional details. Our approach is based on creating a temporal, gps-tagged high-quality image data-set by building a vehicular image capturing platform to autonomously capture high- quality images from different areas of the city. For a given low-quality input image, close images from the data-set are selected which would be used for enhancement in a combined process of salient feature extraction and patch matching. We present the results of applying this technique to
samples of images taken in downtown Amherst.
Augmenting Mobile WiFi Networks (Sep.2008 - Aug. 2009)
Design, implementation, and evaluation of methods to patch communication holes in mobile networks. Advisors:Mark Corner, Brian Levine, PRISMS Lab, UMass
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Abstract:
Open Wi-Fi networks offer a chance to have ubiquitous, mobile connectivity
by opportunistically leveraging previously deployed resources. Open Wi-Fi
access points are densely deployed in many cities, offering high bandwidth
at no cost to the mobile node. Unfortunately, Wi-Fi networks are riddled
with coverage holes, resulting in poor network performance, even if planned
for blanket coverage. To back this claim, we present the results of a
measurement study of a small city's Wi-Fi network---both planned and unplanned
---using mobile nodes, verified with data collected from a second city. We
find that holes can be broadly classified into two categories: (1) permanent
holes due to a lack of Wi-Fi coverage; and (2) transient holes that are due
to mobility and channel characteristics. We show that these holes have a severe,
adverse effect on the performance of network transport protocols.
In this work, we investigate efficient and inexpensive ways for fixing these holes.
Securing Hierarchical Sensor Networks (M.Sc Thesis) (Jun.2006 - Jun.2007)
Design & implementation of a security scheme in a multi-level
hierarchical wireless sensor network that allows secure &
authenticated aggregation processing in all the levels &
accounts for dynamic cluster re-organization. Advisor:Tassos Dimitriou, Algorithm and Security Lab, AIT
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Motivation:
Hierarchical processing in sensor networks offers a number of operational
advantages that cannot be met by flat networks of sensors with their inherent
limitations on power and processing capabilities. Using hierarchical
architectures and in-network processing of information the communication
overhead is minimized by combining data coming from different sources - thus
eliminating redundancy, minimizing the number of transmissions and
eventually saving network energy.
The focus of this research is on securing such processing hierarchies. In
particular security mechanisms must be developed that need to be adaptive to
changes in the roles taken by the sensors. Hence the whole process of
receiving/aggregating data and disseminating commands must be secured
and explain how the security protocol can support changes to the roles of
sensors in the network. This is necessary since the cooperative and
collaborative nature of sensor networks may necessitate the use of
configuration actions that lead to energy savings. Hence the protocol must
support admission of new sensors and reorganization of existing clusters.
Research Structure:
Implement primitives that allow for cluster organization of the sensor
nodes into multi-level hierarchies.
Key establishment protocols between sensors and aggregators that allow
for secure and authenticated aggregation processing for all levels of the
network hierarchy.
Extend the basic primitives to allow, for cluster reorganization and
adaptive formation of new clusters taking security into mind.
Study the efficiency and scalability properties of the protocol using a
demonstrator to get experimental data.
Development Specific Details
The coding, testing and measurements is performed under TinyOS and on MICA2
and TMote platforms.
Real World Sensor Network Application for Protection of Caretta-Caretta Turtles (Jun.2006 - Jun.2007)
Design, implementation and deployment of a sensor network in order to
protect endangered Caretta-Caretta turtles in Greek island of Zakynthos
with support of WWF Hellas Organization. Advisor:Tassos Dimitriou, Algorithm and Security Lab, AIT
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Motivation:
The loggerhead sea turtle known as the Caretta-Caretta has become an endangered
specie that can only be found in the Mediterranean Sea. The turtles where leading
a peaceful existence in the waters and beaches of Zakynthos but the extension and
growth of touristy industry has interrupted their natural rhythms: many of them
disappeared and the specie is now under direct threat.
Our research group at AIT with the support of WWF Hellas Organization deploys
a sensor network to monitor and protect an area close to the beach
in Zakynthos from fire.
WWF claims that the ashes from a possible fire will be transferred to the beach
in case of a rain, and that will damage the sand quality, affecting future nesting
attempts.
Research Structure
Design and implementation of the required distributed architecuter and related softwares
Design, study, use and optimize power management techniques
(especially in MAC Layer and Application Layer) in TinyOS
suitable for the requirements of this application.
Resolving real-world deployment challenges
Development Specific Details
The coding, testing and measurements were performed under TinyOS
and TMote platform.
Multiple and/or Directional Antennas for Sensor Network Nodes (Aug.2006 - Mar.2007)
Study the effects of using multiple and/or directional antennas
on energy efficiency of transmission and reception as well as
to find out new techniques for packet scheduling in MAC layer. Advisor:Antonis Kalis, Wireless and Sensor Networks Lab, AIT
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Motivation:
One of the major causes of fast power drain in sensor networks is
message overhearing. In order to resolve this problem several schemes
have been proposed; try to eliminate message overhearing
by associating schedules of periodic listen and sleep intervals. Most of
these approaches are designed for sensor nodes with omni-directional antennas.
However, in this research we are moving towards a new design of a MAC layer scheme
that employs directional antennas for lifetime improvement of sensor nodes.
Research Structure:
Design and implementation of several experiments dealing with different
polarizations, different transmission powers, different distances and
different angles in a network of multiple nodes with directional and omni-directional
antennas.
Optimal coloring is well studied.
Development Specific Details
The coding, testing and measurements are performed under TinyOS and CMU-Max (and RTLink)
software environments and on MICAZ and CMU FireFly platforms respectively. A type of directional
antenna created at AIT is also used in the experiments.
LEE: Lightweight Energy Efficient Encryption Algorithm (Sep.2006 - Mar.2007)
Design, analysis and implementation of an efficient block cipher suitable
to be used in low-power tiny devices such as the sensor network nodes. Advisor:Nikos Komninos, Algorithm and Security Lab, AIT
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Abstract:
Data confidentiality in wireless sensor networks is mainly
achieved by RC5 and Skipjack encryption algorithms. However,
both algorithms have their weaknesses, for example RC5 supports
variable-bit rotations, which are computationally expensive
operations and Skipjack uses a key length of 80-bits, which
is subject to brute force attack. In this paper we introduce
a light-weight energy-efficient encryption-algorithm (LEE)
for tiny embedded devices, such as sensor network nodes.
We present experimental results of LEE under real sensor
nodes operating in TinyOS. We also discuss the secrecy of
our algorithm by presenting a security analysis of various
tests and cryptanalytic attacks.
Transparent Security Platform for Wireless Sensor Networks (Jan.2006 - Sep.2006)
Analysis, design & implementation of an energy-efficient, easy-to-use,
scalable and flexible security platform under TinyOS that protects the
WSN against replay and node capture attacks along with providing basic
security services. Advisor:Tassos Dimitriou, Algorithm and Security Lab, AIT
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Abstract:
We introduce a link layer security
platform for wireless sensor networks. At the heart of this
platform, lies our key management module facilitating an efficient
scalable post-distribution key establishment that allows the
platform to provide different security services. We have developed
this framework under TinyOs and have tested it with MICA2
motes. To the best of our knowledge this is the first implemented
security platform for sensor networks that provides acceptable
resistance against node capture attacks and replay attacks. The
provision of security services is completely transparent to the
user of the framework. Furthermore, being highly scalable and
lightweight, this platform is appropriate to be used in a wireless
sensor network of hundreds of nodes.
.Sense: A Secure Framework for WSN Data Acquisition, Monitoring & Command (Jan. 2006 - Aug. 2006)
Design, implementation & deployment of a distributed system acting as
a tool to be used by non-advanced end-users for sensor network data
acquisition & command providing a transparent end-to-end security service
& end-user real-time interaction with the sensor network. Advisors:
".Sense" is an end-to-end security framework for sensor
network data acquisition, monitoring and command. In order to
provide security service inside the sensor network two security
protocols are implemented. The first is a key establishment
algorithm in which sensor nodes agree on common keys to use for
securing communications among them. The second is a scheme in
which the base station can issue commands in authenticated
manner to the network. We are also using typical security schemes
such as SSL to connect the end-users to the system.
Defining Novel Fuzzy Logic Operators (B.Sc Thesis)(Jan. 2004 - Jan. 2005)
Surveying flaws of classical reasoning systems and
Defining T-Norm & S-Norm fuzzy operators based
on diffusion phenomenon in nature. Advisor:Saeed Bagheri Shouraki, Computer Eng. Dept., Sharif University of Technology
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Abstract:
This research project aims to investigate classical logic and the contemporary technology,
detect the existing drawbacks and provide some directions to resolve them. Fuzzy logic
is emphasized as a method that is able to solve the mentioned deficiencies in classical
reasoning systems, at least at the implementation level. Furthermore, we will introduce and
elaborate certain characteristics of a fuzzy operator called IDS (Ink Drop Spread) and we will
try to introduce novel fuzzy T-Norms and S-Norms based on this operator and the physical equation
of dissolving ink in water. On the other hand, by noticing at the importance of the concept of
language in modelling different phenomena, as well as being aware of the fact that fuzzy logic
itself tries to adjust the modelling process to the natural language and the usual reasoning of
the human brain, we provide certain explications on the very concept of language and its related
theories as well as its relation with human mind. We also emphesize why "language" has to be
seriously taken into account in the process of modelling different phenomena in the world.
Design and Implementation of Small-Sized Soccer Player Robots (Sep. 2003 - Feb. 2004)
Responsible for primary studies in image processing and system planning
as well as conducted feasibility studies of practical playing algorithms
that accounted for mechanical limits. Advisor:Mohammad Taghi Manzoori, Computer Eng. Dept., Sharif University of Technology
Design and Implementation of Simulated Soccer Player Robots (Sep. 2001 - Feb. 2003)
Responsible for analysis, design and implementation of a multi-agent
system of virtual soccer players in preparation for competition against
virtual opponents without human interference during the game. Advisor:Jafar Habibi, Computer Eng. Dept., Sharif University of Technology
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More Information:
This is the vision of the RoboCup community:
By the year 2050, develop a team of fully autonomous
humanoid robots that can win against the human world
soccer champion team.
The interesting vision of this community provides an opportunity
for extensive research in multi-agent systems and artificial
intelligence. There several leagues (humanoid robots, middle-sized
robots, small-sized robots and simulated robots)in which different teams
from different educational institutes participate in a yearly
event. Check out more information about Robocup here.
Sharif University has been an active participant in RoboCup leagues for quite a number of years.
I was a member of Sharif Aras and Sharif Arvand simulated soccer player robots teams during my
undergraduate studies. Together with other members of Sharif Aras, we got the fifth rank in German
Open 2001. Check out the detailed results of the matches here.
Work Experience
Freelance Software Developer (Jan.2012 - Mar.2012)
Development of a software for marketing research aimed at understanding consumer procrastination.
Isenberg School of Management, UMass, Amherst
Developer (Nov.2006 - Jul.2007)
Development of a security system for distributed mobile phone games
AIT/Intralot Co., Athens, Greece
Analyst, Software Designer & Implementer (Jun.2003 - Jun.2005)
Analysis, design, and implementation of PCP (Phone Call Pager),
a distributed CORBA application under Microsoft Windows.
Nebras Informatics Co., Tehran, Iran
Systems Analyst (Jun.2002 - Sep.2002)
Responsible for analysis phase of a system utility software
to be used by computer engineering students as an aid to
their course studies.
Danesh Pajouhan Firm, Tehran, Iran
Developer (Sep.2001 - Jun.2002)
Web designer and developer in Sharif Virtual University project.
Responsible for analysis & design of a secure system for Hadi Systems Co. in order to protect its audio/visual products from being captured or cracked.
Sharif Computing Center, Tehran, Iran
