Random Pair Key Distribution Based Security in Ubiquitous Computing

Secure communications in wireless adhoc networks operating under adversarial conditions require providing pairwise keys to adhoc nodes. In large scale deployment scenarios, there is no prior knowledge of post deployment network configuration since nodes may be randomly scattered over a hostile territory. Thus, shared keys must be distributed before deployment to provide each node. For large adhoc networks it is infeasible to store a unique key for all other nodes in the key-chain of an adhoc node. Providing a suitable key establishment scheme in wireless adhoc networks is challenging due to all the characteristics of these networks, such as limitations of power, computation capability and storage resources. Pairwise key establishment is a fundamental security service in adhoc networks; it enables nodes to communicate securely with each other using cryptographic techniques. However, due to the resource constraints, it is infeasible to use traditional key management techniques such as public key cryptography and key distribution center (KDC). To facilitate the study of novel pairwise key predistribution techniques, this paper presents a general framework for establishing pairwise keys between nods on the basis of Scalable Method of Cryptographic Keys. This paper then presents two efficient instantiations of the general framework: a random key generation and a random subset assignment key distribution scheme. The analysis in this paper indicates that these two schemes have a number of well defined properties, including high probability (or guarantee) to establish pairwise keys, tolerance of node captures, and low communication overhead. Finally, this paper presents a technique to reduce the computation at nodes required by these schemes.