  Research on sensor networks has become much more active and is currently
being applied to many different fields. However since sensor networks are
limited to only collecting and reporting information regarding a certain event,
and requires human intervention with that given information, it is often
difficult to react to an event or situation immediately and proactively. To
overcome this kind of limitation, Wireless Sensor and Actor Networks (WSANs)
with immediate-response actor nodes have been proposed which adds greater
mobility and activity to the existing sensor networks. Although WSANs share
many common grounds with sensor networks, it is difficult to apply existing
security technologies due to the fact that WSANs contain actor nodes that are
resource-independent and mobile. Therefore, this research seeks to demonstrate
ways to provide security, integrity, and authentication services for WSANs
secure operation, by separating networks into hierarchical structure by each
node's abilities and provides different encryption key based secure protocols
for each level of hierarchy, Pairwise key, node key, and region key for sensor
levels, and public key for actor
