Data security in unattended wireless sensor networks

Wireless Sensor Networks (WSNs) encompass a multitude of small autonomous devices that monitor the deployment area and process acquired information. They are usually managed by an on-line trusted entity called a sink. However, some emerging WSNs scenarios preclude constant presence of an on-line sink. In such a disconnected or unattended settings, sensors must accumulate sensed data until it can be off-loaded to an itinerant sink. Furthermore, if the operating environment is hostile, there is a very real threat of sensor and data compromise.;In this thesis we define Unattended Wireless Sensor Networks (UWSNs), characterized by a sporadic presence of the sink. Sensors can remain unattended for a long time and must retain their measurements until the next sink visit. The UWSN model motivates a new and powerful mobile adversary that 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.;Lack of an on-line trusted sink and the compromise power of the adversary, make security techniques in prior WSN security literature unsuitable for the UWSN setting. We provide novel solutions to secure data in UWSNs against an adversary that aims to learn, modify or delete collected data. Proposed protocols take advantage of sensor collaboration to obtain a surprising degree of resilience in the presence of a mobile adversary.