الفهرس 
1. INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Wireless Sensor Networks (WSNs) consist of multitude of small
autonomous devices those monitor the deployment area and process
acquired information. They are usually managed by an on-line trusted
entity called a sink; the sink is the only unconditionally trusted authority.
However, some emerging WSNs scenarios preclude constant presence
of an on-line sink, if the sink is not connected to the nodes for a period of
time, there is no real-time communication between the sensors and the sink.
The network is considered as unattended and it is defined as Unattended
Wireless Sensor Networks (UWSNs), characterized by a sporadic presence
of the sink, in UWSN, a trusted mobile sink visits each node periodically
to collect data. In such a network, sensors can remain unattended for a long
time and must retain their measurements until the next sink visit; they must
accumulate the sensed data until it can be off-loaded to an itinerant sink.
Furthermore, if the environment is hostile, there is powerful mobile
adversary that aims to learn, modify or delete collected data, it can
compromise up to a certain number of sensors within a particular time
interval; this interval can be much shorter than the time between successive
sink visits. Given enough such intervals, the adversary can subvert the
entire network as it moves through sets of compromised sensors, gradually
undermining security.
UWSN can be deployed in environments where it is not practical for the
sink to be online all the time. Lack of an online trusted sink and saving data
in the memory of the nodes for a long time beside the compromise power
of the adversary, causes security problems due to the lack of tamperresistant
hardware. Data collected by the nodes has to be secured until the
next visit of the sink. Securing the data from an adversary in UWSN is a
challenging task.
Security techniques in prior WSN security literature are unsuitable for
the UWSN setting. We provide novel solutions to secure data in UWSNs
against an adversary and ensure data reliability in UWSN. In this thesis,
we propose effective algorithms to increase data security and data survival
in a homogeneous UWSN, without implementing cryptography.
The proposed algorithms will depend on the self-healing principal, they
take advantage of sensor collaboration and sensor mobility to obtain a
surprising degree of resilience in the presence of a mobile adversary. The
proposed solutions are analyzed both mathematically and using
simulations to prove that the proposed solutions are better than the previous
ones in terms of security and communication overhead. The proposed
Algorithms are successfully defeating adversary even when it has enough
energy and time to corrupt network.