Review Reports

Round 1

Reviewer 1 Report

The paper was written rather in a marketing manner than scientific one. 9 of 22 pages contain the motivation and literature review of the subject, 6 pages contain performance and security analysis of the proposed solution. But the most important, in my opinion, part of the work concerns developed IoT architecture. The last mentioned description is general, pure, skim and not satisfied.  I have not certainty that such system has been fully implemented

 

Author Response

Dear Reviewer,

 

Thanks for the comments and suggestions. We appreciated them. Our responses are in the file attached to this message.

 

Kind regards,

 

The Authors

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper proposes a blockchain storage architecture focused on license plate recognition systems.
Here are some comments which can help to improve the paper.

1) I would expect to see more justification for the research problem in the Abstract section. There are even some very general sentences in Abstract which does not add anything to the abstract, for example: "however, no definitive solution was found." or "several issues must still be taken into account". I suggest revising the Abstract and make more specific statements about the research problem. The abstract has nothing about the methodology of the research. It means, after reading the abstract I have no idea about the work done in this research.

2) It seems this work is an extension of a previously published paper by the same author, referred in paper [6]. I would expect to see the exact differences of these two papers in the Introduction.

3) I suggest authors list their contributions in a list. It is not clear for me what the main contribution is.

Author Response

Dear Reviewer,

 

Thanks for the comments and suggestions. We appreciated them. Our responses are in the file attached to this message.

 

Kind regards,

 

The Authors

Author Response File: Author Response.pdf

Reviewer 3 Report

This work proposes a Blockchain based approach to store data from license plate recognition systems. The paper is well written and easy to read. There are however several issues that require more attention:

1. The protocol in step (iii) on page 12 mentions that “if the privacy preference of this license plate allows the image to be captured, the gateway stores its image in a storage service.” But what happens if the privacy setting does not allow to store, will the image be deleted? Or stored encrypted with the public key? This has to be clarified to avoid misinterpretations and presented in clearly as alternative in step (iii) of the protocol.
2. The main limitation of the work is that there is no scalability discussion, i.e., how this system will cope with data for the same car coming from different record points during the same day and how will this increase the size of the data-base over days, months or years? Readers need to have the exact figure on the size of the database for a single city, based on the expected number of cars and LPR points that report such data.
3. Again, regarding scalability, the authors only briefly mention on page 15 that “the system may not remain scalable for using it in more than one city” but except for the sentence that follows there is little discussion on this. What is the main problem regarding scaling up over multiple cities?
4. The console prints in Figure 5 are not fully explained in the text, for example the meaning of the logsBloom record cannot be inferred from the text.
5. There is an English error in this sentence: “information that does not are related to criminal activities”.
6. The discussion on related work is comprehensive, however the authors may also look at the paper below which uses smartphones for LPR: Andreica et al. Secure V2V Communication with Identity-based Cryptography from License Plate Recognition. In2019 Sixth International Conference on Internet of Things: Systems, Management and Security (IOTSMS) 2019 Oct 22 (pp. 366-373). IEEE.

Besides these fixes, I find the paper interesting and easy to read.

Author Response

Dear Reviewer,

 

Thanks for the comments and suggestions. We appreciated them. Our responses are in the file attached to this message.

 

Kind regards,

 

The Authors

Author Response File: Author Response.pdf

Reviewer 4 Report

This paper is an extension of a previous conference paper published by the authors, with more detailed description of the algorithms and evaluation results. However, the design, evaluation and presentation need a significant improvement to clarify the contribution.

1) The paper proposes to use a private Ethereum as the blockchain system. As the blockchain is controlled by the government, how to ensure the blockchain is not modified by insiders?

2) The related work section only lists a number of existing works. It is hard to find the relationships between these papers, especially the relationship between this paper and the existing works.

3) Section 4. The design is not convincing.

- It seems that smart contracts only save the users’ privacy preferences. How can this simple contract ensure the privacy protection? What if the gateway does not follow the procedure, i.e. does not follow the contract?

- ECC are normally not used for encryption. How is the specified encryption implemented?

- Using public keys to implement anonymity? How to ensure that the attackers cannot correlate user’s id with the public key?

4) Evaluation.

- The blockchain is private. Why is mining required? Why is Gas used in a private blockchain? Why do the costs of the smart contract change with the addresses (How are the addresses saved in the contract)? If each user uses one contract, Can the total Gas cost be calculated directly from the contract cost * the contract number?

Author Response

Dear Reviewer,

 

Thanks for the comments and suggestions. We appreciated them. Our responses are in the file attached to this message.

 

Kind regards,

 

The Authors

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Authors responces to my comments and changes done in the article satisfy my. I have not new comments 

Reviewer 3 Report

The paper has improved and I think it it is suitable for publication.