# Blockchain Application in Internet of Vehicles: Challenges, Contributions and Current Limitations
## 5 Findings and Future Directions
### Review Findings: Limitations of Using Blockchain in IoV-Assisted Smart Grid
Latency, throughput and scalability are examples of such performance metrics. The scalability of the current blockchain solution further restricts its adoption in large-scale IoV. The scalability of blockchain may be assessed by comparing transaction throughput per second to the number of IoV nodes and simultaneous processes, causing numerous blockchain implementations to suffer from low throughput [27]. Bitcoin, for instance, can only handle seven transactions per second. In comparison, VISA can handle approximately 2000 transactions per second, whereas PayPal can process 170 transactions per second [106; 107]. Before blockchain will be widely adopted in the IoV, it must demonstrate that it can provide the needed scalability to support the critical IoV applications and ensure road safety. The blockchain technology has already passed the proof of concept stage, but it must now be scaled up. **Limitation 3--Resource Constraints and Limited storage:** The majority of IoV devices have limited resources. Sensors, RSUs, EV batteries, charging points and other devices, for example, have inadequate processing capabilities, limited storage space, insufficient battery power and inadequate network connection capabilities. Yet, the consensus algorithms of blockchains sometimes necessitate a large amount of computer power and energy usage. Proof of Work, for example, was proven to consume a lot of energy [39]. As a result, consensus techniques with high energy consumption may be impractical for low-power IoV devices. On the other hand, the large amount of blockchain data makes it impossible to completely implement blockchains throughout the IoV [38]. As a result, it is difficult to keep the whole blockchain on each IoV device. Furthermore, the enormous data generated in the IoV, in near real time, complicates the issue [108]. Consequently, strategies to restrict the amount of storage resources required by the ledger are needed. **Limitation 4--Privacy and Security:** Adopting blockchain in the IoV provides security and prevents data manipulations by ensuring data immutability. Nonetheless, considering that blockchain is built on different techniques, it cannot immediately ensure security and privacy [109]. A few of these techniques that can protect the security of theinformation (transactions and/or records) inside the blocks, and also the privacy of the IoV users and devices, include advanced cryptographic techniques, pseudonyms and off-chain storing [65]. Transactions in BTC, for example, are conducted using IP addresses rather than participants' actual identities, thereby maintaining anonymity. Furthermore, one-time accounts in BTC are created to ensure user privacy. These safeguards, however, are not robust. User pseudonyms, on the other hand, may be cracked by recognizing and inferring the transactions connected with a single common user [76]. Furthermore, the entire storing of transaction data on the blockchain may result in possible privacy leaks [110]. In blockchain, any transaction-related information, including senders'/recipients' records and value amounts, are publicly accessible and open. As a result, even if users employ pseudonyms, this may not help them remain fully anonymous, raising security and privacy issues [111]. Moreover, IoV-participants' actions and energy profiles, such as energy consumption, production, energy use patterns, driving profiles and other records, can be monitored and leaked by analyzing the publicly available data in the blockchain. Thus, users' true identities may be disclosed [112]. Last but not least, blockchain in IoV-assisted smart grids grid has the potential to expand across an extended geographical area. In such a scenario, it is realistic to say that multiple chains and off-chains will be used. In such multi-chain environments, it is extremely difficult to ensure privacy and security [64].