Abstract: Internet of Vehicles (IoV) realizes the interconnection between vehicles and vehicles and between vehicles and roadside units, by which it shares driving and traffic information and offers a convenient and safe driving environment for both drivers and passengers. However, the credibility problem of vehicle information is to be solved urgently for the false information threatens driving safety. To improve the credibility of vehicle information, this paper proposes a credit model of Internet of Vehicles. The model sets a method of calculating vehicles’ credit according to vehicle information, creates a consensus mechanism of vehicles’ credit on the foundation of the DAG-based distributed ledger, then makes the high-credit vehicles get the accounting right easier by dynamically adjusting the difficulty of consensus, and finally ensure the credibility of the information in the Internet of Vehicles. Through analysis, it is found that this mechanism can effectively solve the credibility problem of vehicle information and resists common attacks in the Internet of Vehicles. Compared with traditional blockchain, this consensus mechanism, with its higher consensus efficiency and lower energy consumption, is suitable for the Internet of Vehicles of limited computing and storage resources. 

Key words: font-size:14px, ">consensus mechanism, vehicular network, blockchain, reputation management, directed acyclic graphs ,  ,

摘要： 车联网通过实现车与车、车与路边单元的互联互通，共享驾驶信息和交通消息，为司机与乘客提供一个方便、安全的驾驶环境，但是虚假消息会对驾驶安全造成威胁，车辆消息可信度问题亟待解决．为解决此问题本文提出了一种车联网信誉值模型，该模型设计了一种根据车辆消息计算车辆信誉值的方法，然后基于有向无环图的分布式账本提出了一种车辆信誉的共识机制，通过动态调整共识难度，使信誉高的车辆更容易获得记账权，从而可以保证车联网中消息的可信度．通过分析发现，该机制可有效解决车联网中车辆消息的可信度问题，并且能够抵御常见的车联网攻击，相较于传统区块链该共识机制具有更高的共识效率和更低的能量消耗，适用于计算和存储资源受限的车联网环境．

关键词: 共识机制, 车联网, 区块链, 信誉管理, 有向无环图