Lightweight Blockchain Consensus Protocols for Vehicular Social Networks

This paper presents lightweight blockchain consensus protocols that are specifically designed for vehicular social networks, or other networks that resemble them. They are lightweight in the sense that no puzzles are required to be solved and no cryptocurrency systems are required to be built beforehand. Various scenarios are considered, including whether the communication is reliable and whether the vehicle grouping is static. Although we break our solution of the consensus problem into private chain and public chain, we provide a scheme to smoothly bridge between them. Theoretical analysis is provided to guarantee the algorithms to succeed with high probability, before experiments are conducted to verify the algorithms and compare their theoretical performance versus simulation performance, namely worst-case performance versus average performance.

I. Introduction

Bitcoin blockchain [1] was an ingenious way for distributed systems to reach consensus with high probability. The basic idea is that in each time period (about 10 minutes), it is most likely to have one node who solved a puzzle in the ideal situation, although forks might arise temporarily mainly due to network delay. The puzzle is based on a one-way function and requires the output to have an adjustable length of leading 0’s. This process resembles random sampling from the population. The chances of being selected as the next leader are proportional to the computational power possessed. Therefore, as long as the population of good nodes has more than of the total computational power, over the long term, the valid hash chain will outpace invalid chains with high probability.