Table 7.

Features of blockchain and smart contract methodologies for ethical CCAM challenges.

Ref	Challenge	Technology	Advantages	Disadvantages	Impact
[56]	Accountability	Blockchain—PoW	The identity of the parties involved in the road network is not disclosed. It is an appropriate methodology to protect against identity disclosure and non-attribution attacks.	It has no filtering techniques for the data generated by the vehicle. Using different key pairs for blockchain and NDN functions puts a strain on system performance.	Combining blockchain and NDN to provide secure distributed V2X communications while maintaining privacy.
[57]	Accountability	Permissioned Blockchain and Smart Contracts—PoW	Reduces message transmission time and network load	It does not meet the needs of real-time VANETs.	Event message search mechanism through blockchain and smart contracts maintaining the anonymity and accountability of VANET network users and improving the performance of the 5G network by applying SDN technology.
[58]	Accountability	Blockchain and Smart Contracts—DpoS, PoW	Small block storage pressure and high consensus algorithm efficiency	Not tested in real scenarios	A novel hierarchical certificate service chain based on blockchain for the implementation of a new reputation measurement model for effective authentication of node’s identity in VANETs
[59]	Responsibility	Blockchain—PBFT	Platform capable of providing trust to the involved entities of VANETs	There are shortcomings in the methodology as far as privacy protection is concerned	Propagation of messages based on reputation between connected vehicles and a combination of new technologies such as SDN, fog computing, and blockchain.
[60]	Responsibility	Permissioned Blockchain and Smart Contracts—PoA	The reputation score is available to individual nodes when requested with no central dependency.	The process of registering a vehicle does not guarantee concealment of the vehicle’s location	A reputation mechanism for generating, exchanging, and storing data between vehicles and of nodes in VANETs for incising vehicle and driver accountability.
[43]	Trust management	Blockchain and Smart Contracts—PoW and PoS	It provides data with integrity, security, and reliability.	Vulnerable to modeling attacks on PUFs.	Model for creating a distributed trust management system that registers and recalls vehicles using blockchain and smart contracts and the unique ID generated by the PUFs of the vehicles’ SoCs.