Delay-Aware Hash Tree for Blockchain on Vehicular Delay Tolerant Networks

Abstract

Blockchain (BC) technology is being applied to various applications with a lot of interest in data security. One of these applications is being applied in Vehicular Ad-hoc Networks (VANETs). Due to the high mobility of VANETs, frequent changes of the network topology occur and the network connection can be lost. These cause a high delay and network partitioning. Therefore, a new research paradigm called Vehicular Delay Tolerant Networks (VDTNs) is introduced to study these issues. When BC technology is applied to VANETs, it constructs a data gathering tree or schedules a routing path in the network layer for efficient data collection and handling network disruption. Furthermore, frequent topology updates happen. However, if the BC hash tree is not updated in the application layer, this causes an increase in network delay due to the inconsistency between the data gathering tree and the hash tree. In this paper, we describe this problem and propose new greedy algorithms to construct a hash tree that considers the network connection time on VDTNs. In such a hash tree, the inconsistency between the hash tree and the data gathering tree can be resolved by constructing the data gathering tree in consideration of the network connection time. Additionally we analyze the time complexity of the proposed algorithms.