Byzantine resilient synchronization for content and presence updates in MANETS

In this paper, we present techniques for synchronizing nodes that periodically broadcast content and presence updates to co-located nodes over an ad-hoc network, where nodes may exhibit Byzantine malicious behavior. We first propose an algorithm for synchronizing the periodic transmissions of all the nodes in an attacker-free multi-hop network. This allows nodes to save battery power by switching off their network cards without missing updates from their neighbors. We then introduce a suite of spoofing attacks and show that they are able to disrupt synchronization and destabilize the network even when launched by a single attacker in large, multi-hop networks. Finally, we devise a rating based algorithm that rates neighbors based on the consistency of their behaviors. By favoring well-behaved nodes in the synchronization process, we show that we can address the issue of Byzantine malicious behavior very effectively. Our evaluation shows that the algorithms are computationally efficient and, for the setup considered, extend the device lifetime by 30% over an always-on Wi-Fi scenario. Moreover, in the presence of attacks, our rating based algorithm quickly stabilizes the synchronization process and reduces the number of lost updates by 85%.