Mobile ad hoc networking offers convenient infrastructure-free communication over the shared wireless channel. However, the nature of ad hoc networks makes them vulnerable to security attacks. Examples of such attacks include passive eavesdropping over the wireless channel, denial of service attacks by malicious nodes as well as attacks from compromised nodes or stolen devices. Unlike their wired counterpart, infrastructureless ad hoc networks do not have a clear line of defense, and every node must be prepared for encounters with an adversary. Therefore, a centralized or hierarchical network security solution does not work well.

This work provides scalable, distributed authentication services in ad hoc networks. Our design takes a self-securing approach, in which multiple nodes (say, k) collaboratively provide authentication services for any node in the network. This paper follows the design guidelines of [7] and makes several new contributions. We first formalize a localized trust model that lays the foundation for the design, and then expand the adversary model that the system should handle. We further propose refined localized certification services, and develop a new scalable solution of share updates to resist more powerful adversaries. Finally, the new solution is evaluated through simulations.