An opportunistic batch bundle authentication scheme for energy constrained DTNs

Bundle Authentication is a critical security service in Delay Tolerant Networks (DTNs) that ensures authenticity and integrity of bundles during multi-hop transmissions. Public key signatures, which have been suggested in existing bundle security protocol specification, achieve bundle authentication at the cost of an increased computational, transmission overhead and a higher energy consumption, which is not desirable for energy-constrained DTNs. On the other hand, the unique "store-carry-and-forward" transmission characteristic of DTNs implies that bundles from distinct/common senders can be buffered opportunistically at some common intermediate nodes. This "buffering" characteristic distinguishes DTN from any other traditional wireless networks, for which an intermediate cache is not supported. To exploit such a buffering characteristic, in this paper, we propose an Opportunistic Batch Bundle Authentication Scheme (OBBA) to achieve efficient bundle authentication. The proposed scheme adopts batch verification techniques, allowing a computational overhead to be bounded by the number of opportunistic contacts instead of the number of messages. Furthermore, we introduce a novel concept of a fragment authentication tree to minimize communication cost by choosing an optimal tree height. Finally, we implement OBBA in a specific DTN scenario setting: pocket-switched networks on campus. The simulation results in terms of computation time, transmission overhead and power consumption are given to demonstrate the efficiency and effectiveness of the proposed schemes.