Towards Secure and Self-stabilizing Sensor Network Services for Civil Security
Licentiate thesis, 2011
Wireless sensor networks, consisting of a vast number of small
sensor nodes that can monitor large areas, are a promising field
with many possible applications in many different application
areas. In civil security settings, e.g., they can be of great help
by monitoring things like disaster areas, restricted areas, crowds
and structural integrity.
The sensor nodes are deployed in an area that is to be monitored in
some way. Typically the nodes do not have any preexisting
information about network topology and instead communicate
wirelessly to organize the network.
Sensor nodes are often very limited in computing power, memory and
battery life. In addition the traffic patterns are generally
different than for other types of networks. Therefore, algorithms
often need to be tailor-made for sensor networks. Furthermore, for
networks that consists of a very large amount of nodes, algorithms
have to scale well.
Security and fault tolerance is of high importance for many sensor
network applications and for civil security in particular. The
sensor network application needs to remain functioning even when
nodes fails or are attacked in different ways. Sensor nodes often
reside in harsh environments that can destroy them, during or after
deployment. One potent form of fault tolerance is
Self-stabilization. A self-stabilizing system can recover from an
arbitrary state within a finite amount of time.
Security in wireless sensor networks is further complicated by the
fact that the nodes often are physically available for attackers to
destroy, capture or manipulate in other ways. The threat of
compromised nodes inside the network that are controlled by an
attacker is a concern that needs to be taken into account.
High precision synchronized clocks are a fundamental need of many
applications and of other services. We present the first secure and
self-stabilizing algorithm for sensor networks that is resilient
towards against attacks both from the outside and by compromised
nodes from the inside.
Sensor nodes also needs to organize their own network. A common way
is to cluster nodes together into groups. They are used by many
applications and other fundamental services. We present a secure and
self-stabilizing algorithm for clustering. It uses redundant paths
to be resilient against captured nodes in the network.