  With the development of wireless communication technologies which
considerably contributed to the development of wireless sensor networks (WSN),
we have witnessed an ever-increasing WSN based applications which induced a
host of research activities in both academia and industry. Since most of the
target WSN applications are very sensitive, security issue is one of the major
challenges in the deployment of WSN. One of the important building blocks in
securing WSN is key management. Traditional key management solutions developed
for other networks are not suitable for WSN since WSN networks are resource
(e.g. memory, computation, energy) limited. Key pre-distribution algorithms
have recently evolved as efficient alternatives of key management in these
networks. In the key pre-distribution systems, secure communication is achieved
between a pair of nodes either by the existence of a key allowing for direct
communication or by a chain of keys forming a key-path between the pair. In
this paper, we propose methods which bring prior knowledge of network
characteristics and application constraints into the design of key
pre-distribution schemes, in order to provide better security and connectivity
while requiring less resources. Our methods are based on casting the prior
information as a graph. Motivated by this idea, we also propose a class of
quasi-symmetric designs referred here to as g-designs. These produce key
pre-distribution schemes that significantly improve upon the existing
constructions based on unital designs. We give some examples, and point out
open problems for future research.
