Video Blockchain: A Decentralized Approach for Secure and Sustainable Networks with Distributed Video Footage from Vehicle-Mounted Cameras in Smart Cities
Round 1
Reviewer 1 Report
The article deals with an interesting topic with important practical applications. In general, I consider that the paper is well presented, so I will only make some recommendations that I consider can improve the quality of the manuscript.
The introduction is quite complete, having synthesized the existing literature on the problems of the paper, and adequately contextualizing the reader.
The methodology is adequately presented. In the results, I recommend improving the quality of the graphs, so that they are clearer and more attractive to the reader.
I consider that a discussion section should be included. This section should explain and contrast the data obtained with other research in this field of study. Thus, the authors should answer questions such as: were the results in accordance with expectations, are the results congruent with other similar research? And, if not, what elements explain the discrepancies that have occurred?
I also recommend including a specific section with the limitations of the study and future lines of research.
Author Response
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Reviewer 2 Report
This paper uses the decentralized nature of blockchain to implement a vehicle-based surveillance system across the smart city. Overall this is an important research topic and this manuscript presents an effective solution.
1. The research motivation in the Introduction section is not convincing. I cannot figure out the existing research challenges and necessity of introducing the blockchain into similar existing systems.
2. The related work section is not organized. I would expect a better organization with different subsections so that the state-of-the-art relevant studies can be captured.
3. Figures 1-3 have a low resolution and should be improved.
Comments for author File: 
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Author Response
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Reviewer 3 Report
In this research paper, the concept of video blockchain for establishing connectivity between vehicles in a smart city was explored by utilizing blockchain. By leveraging intelligent vehicular systems that provide location-based vitalization through multiple deployed cameras in vehicles, this study can expand the scope of collecting video surveillance data for the purpose of observation, thereby enhancing overall situational awareness.
Before the publication, the following issues should be addressed.
1 The authors utilize the decentralized nature of blockchain to implement a vehicle-based surveillance system across the smart city. So please explain how to deal with the data synchronization problem.
2 To ensure the reliability of the system, the integration of two cryptographic functions, hashing and signing, with the blockchain is employed. Please provide the detailed equations for these two equations. Also, provide the derivation procedure for the integration of these two functions.
3. The focus of this study is on combining blockchain technology to achieve sustainable and robust smart solutions for intelligent vehicular distributed video networks. This concept is not complete new idea. So please further emphasize the innovation of this study.
4. In the section of related work, the authors mentioned that computational methods in data mining were employed for anomaly detection. These computational methods are especially important for data modelling and process for the proposed framework. Please search the relevant literature on this topic, and provide a short review on the relevant references papers, e.g., “Analytical study and computational modeling of statistical methods for data mining”“Modelling and forecasting of SHM strain measurement for a large-scale suspension bridge during typhoon events using variational heteroscedasic Gaussian process”“Bayesian dynamic linear model framework for SHM data forecasting and missing data imputation during typhoon events”
5. In conclusions, please add the discussions for the futhre research based on the current work.
6. There are some typos. So please further polish the English writing.
Minor editing of English language required
Author Response
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Reviewer 4 Report
The paper is interesting, but I have the following comments to improve the paper:
Comment 1. What kind of attacks were tested to show the robustness of the proposal in section 4?
Comment 2. A comparison with the state of the art must be presented considering measures about the security or number of attacks to highlight the contributions and differences of the proposal.
Comment 3. The authors did not demonstrate how the five hypotheses established in Section 1 are accomplished with the results presented in Section 4. The authors mainly contributed in Section 4 a comparison of execution time but did not approach how many attacks and what kind of attacks their model can support.
Comment 4. The authors should present their main contribution in a better way. In the abstract, they presented a framework; in the introduction, they refer to the contribution as a method, but in the proposal, they presented a set of algorithms.
Comment 5. The main problem should be presented in a figure to describe the scenario where their contribution should be highlighted.
Comment 6. The author should indicate other metrics to present better how the blockchain is used and how the security is maintained.
Comment 7. A better description of the implementation should be included. Besides, a figure that describes the proposal should be included to understand the modules or processes involved.
Comment 8. The author should include the limitations of their work.
Comment 9. The author should revise the grammar since there are a few errors.
Author Response
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Reviewer 5 Report
This paper is interesting and well written. It has carried out a detailed background investigation, clearly explained the proposed method, and discussed the results in detail. The conclusion is correct. I think the current version is acceptable.
Author Response
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Round 2
Reviewer 2 Report
The authors responds that they have improved all figures including Figure 1-3. However, I cannot tell any difference between the original version and the revised version for Figure 1-3. The authors should be careful about their statement in the response letter.
Author Response
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Reviewer 3 Report
No further comment.
Minor editing of English language required
Author Response
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Reviewer 4 Report
Comment 1. The authors responded, "Given the page limitations, we have focused solely on highlighting the core hypotheses in this paper. The remaining hypotheses are outlined in a broader manner". Hence, why mention some aspects not included or demonstrated in the paper? Why the authors claim in line 66: "...we aim to investigate and validate these hypotheses."
Comment 2. The paragraph of lines 65-69 is unclear since the authors do not specify the main scientific contribution of the work. Besides, in lines 314-316, the authors also indicate the contribution, but it is unclear to me how this contribution differs from the previous works. For instance, the contribution seems related to choosing some algorithms to establish the sequence to produce the blockchain, and the problem located in the Merke tree is not considered. Which is the scientific contribution of the work?
Comment 3. The authors must revise the grammar since there are several errors.
Author Response
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Round 3
Reviewer 4 Report
The authors have improved the paper, and now it reads more fluently. Besides, they answered my questions appropriately by explaining in a different way some of the paper's paragraphs. Hence, I consider it ready to be published.
