  Key establishment in sensor networks becomes a challenging problem because of
the resource limitations of the sensors and also due to vulnerability to
physical capture of the sensor nodes. In this paper, we propose an
unconditionally secure probabilistic group-based key pre-distribution scheme
for a heterogeneous wireless sensor network. The proposed scheme always
guarantees that no matter how many sensor nodes are compromised, the
non-compromised nodes can still communicate with 100% secrecy, i.e., the
proposed scheme is always unconditionally secure against node capture attacks.
Moreover, it provides significantly better trade-off between communication
overhead, computational overhead, network connectivity and security against
node capture as compared to the existing key pre-distribution schemes. It also
supports dynamic node addition after the initial deployment of the nodes in the
network.
