  Due to resource constraints of the sensor nodes, traditional public key
cryptographic techniques are not feasible in most sensor network architectures.
Several symmetric key distribution mechanisms are proposed for establishing
pairwise keys between sensor nodes in sensor networks, but most of them are not
scalable and also are not much suited for mobile sensor networks because they
incur much communication as well as computational overheads. Moreover, these
schemes are either vulnerable to a small number of compromised sensor nodes or
involve expensive protocols for establishing keys. In this paper, we introduce
a new scheme for establishing keys between sensor nodes with the help of
additional high-end sensor nodes, called the auxiliary nodes. Our scheme
provides unconditional security against sensor node captures and high network
connectivity. In addition, our scheme requires minimal storage requirement for
storing keys mainly due to only a single key before deployment in each node in
the sensor network, supports efficiently addition of new nodes after initial
deployment and also works for any deployment topology.
