Binary-Tree-Fed Mixnet: An Efficient Symmetric Encryption Solution
, Juan Pérez Torreglosa 2,†, David Vera 3,†and Manuel Sánchez-Raya 1,†
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis paper introduces a novel anonymous communication system, Binary Tree Fed Mixnets (BTFM), designed to address challenges related to collusion between the delivery node and subsequent nodes, as well as collusion between the delivery node and preceding nodes.
1. The abstract presented the overview of the mixnet system. However, some of the things is presented in general way. Therfore, suggest to improve the contents of abstract such as clearly highlight the main objectvie of this study, the key aspects of proposed method is employed and differs from related works, the outcome/result/contribution of this study, etc. which align with the content inside this paper.
2. The latest reference in this paper is year 2020. Suggest to include more recent related works within past few yers especially year 2023.
3. In the introduction, authors have presented the related works and the findings. However, the aim/objective/motivation, the research gaps, and the major contribution/outcome of this paper is not clearly presented.
4. The proposed method will be used in which domain/application? Suggest to discuss it.
5. SEBM, ESEBM stand for?
[Acronyms/Abbreviations/Initialisms should be defined the first time they appear in each of three sections: the abstract; the main text; the first figure or table. When defined for the first time, the acronym/abbreviation/initialism should be added in parentheses after the written-out form.]
Please check and revise those similar issue, if any.
6. Suggest to use captical letter for the XOR and XORing instead of xor and xoring.
7. Both collusion of the delivery node and following ones, and collusion of the delivery node and previous ones problems are identified from reference 25, ESEBM will be resolved in this study. Any other related works dealing with those problem or reference 25 is the only study on ESEBM? On the other hand, the reference 25 was introduced the ESEBM in year 2011. Suggest to include more related works within past few yers especially year 2023 which are relevent to both problems.
8. What are the purpose for ai, bi, ci, di, a′i, b′i, c′i, and d′i?
9. What are the purpose for A, B, C, and D nodes?
10. Suggest to provide a complete examples how the proposed method is actually working.
11. An experiment has been conducted based on RSA, cMIX, ESEBM and BTFM. However, the experiment did not clearly highlight the performance of the BTFM throughput.
12. How the result/outcome of the proposed method link to the addressed problems in this study?
13. Some typo errors:
line 305, "...ESEBM 1,6 times.". Is it "1.6 times"?
line 321, "overload of 100,1 MB (39,6%).". Is it "100.1 MB (39.6%)"?
Please check and revise those similar mistake, if any.
14. What is the novelty/contribution of the proposed methods differ to others related works?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsJanuary 6, 2024
Review of the manuscript entitled:
Binary Tree Fed Mixnet: An efficient symmetric encryption solution
by
Diego Antonio Lopez-Garcia, Juan Perez Torreglosa, David Vera and Manuel Sanchez-Raya
Manuscript ID: applsci-2811842
General Comments
Mixnets are a tool to achieve anonymity necessary in several applications like e-voting, journalism surveys. These are usually sequences of servers that apply a cryptographic process and permutation of user messages. Most use asymmetric cryptography, which incurs high computational costs.
In the paper a new mixnet scheme based solely on symmetric cryptography is proposed. The scheme based on exploiting a binary tree graph to provide anonymity.
Major comments
The results presented in the paper are interesting and of some importance especially in practical application, but I have the following comments and concerns:
- There should be explicitly given which symmetric (crypto)systems have been applied in BTFM (including in Abstract); only XOR operation is used ?
- The Authors could give more clear argumentation why their system is resistant to the “Collusion of the delivery node with the remaining (other) nodes in the mixnet attack” ? The threshold offered by BTFM “BTFM offers a higher minimum adversary threshold (⌊log_2_(m + 1)⌋)” raises also concerns! Number of nodes m=1024 for example means threshold 10 … not to much. Could the Authors explain this weakness?
The Authors arguing “On the other hand, it is enough to have a single honest node in asymmetric mixnets to ensure privacy.” Could the Authors give (explain) more details here. This is unclear especially keeping in mind the threshold (⌊log_2_(m + 1)⌋.
- Concerning the computational costs, it is obvious that XOR operations are much much faster than operation in public key cryptography systems (RSA, multiplications, etc.). Therefore the comparison between RSA and BTFM at Figure 5 looks strange! Could the Authors comment this fact.
- Concerning the “Proposition 1. The nodes capable of learning user keys must necessarily constitute a cut.” How this property is controlled and executed (when? And each moment) in BTFM?
Minor comments
Editorial form of the paper could be still improve to make it more clear when going deeper into details.
Final Comments
In my opinion, this paper is interesting and of practical meaning. I recommend the paper for publication (minor revision); however, I recommend that before publication, the above concerns should be addressed in the paper.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsIn this manuscript, the authors claim to propose an efficient symmetric encryption solution. Overall, the work presented is devoid of any meaningful innovations or contributions. Furthermore, the organization and writing of the manuscript are extremely poor and seem to fall far below the standards of rigorous scientific research papers. Therefore, it is recommended that the authors first consult any high-quality paper and address a multitude of problems in their manuscript before considering their next submission.
Comments on the Quality of English LanguageExtensive editing of English language required.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have addressed most of the comments.
1. Suggest to change the section 5 title to Experiments and Results
2. Suggest to add a discussion section to highlight/discuss the performance of the proposed method and how it differ to other related works/methods. Or combine the discussion with section 5 and change section 5 title to Results and Discussion.
Author Response
We have chaged section 5 title to "Results and discussion". At the end there is a new paragraph with a comparison between BTFM and previous systems:
"Overall, in light of these experiments, the performance of BTFM stands out from other systems. It is overwhelmingly superior to asymmetric encryption systems (up to 30 times faster), it slightly improves ESEBM in low demand environments (batches of 10.000 users) and clearly surpasses it when demand increases (doubles it from 100,000 users). Furthermore, messages do not increase in size by aggregating headers as in ESEBM, which implies a reduction in the time to send batches between nodes."
Reviewer 3 Report
Comments and Suggestions for AuthorsAfter several revisions by the authors, the quality of the manuscript has improved to some extent. However, there are still some obvious problems that persist in the manuscript.
1. There are redundant ORCIDs in the author list.
2. Obviously, the information in the institutional list is incomplete. Please refer to any high-level paper to correct this problem.
3. "Featured Application: e-voting, anonymous debates, journalism, privacy in the Internet." should be removed.
4. Lines 14 and 15 also appear to be redundant and should be removed.
5. There are different styles of reference citations in the manuscript, such as "[1], [2]" and "[14][15]". The authors should maintain a consistent citation style.
6. Numerous places in the manuscript are missing necessary spaces, such as “ESEBM is an evolution of SEBM[29] and is explained in detail in [30].”
7. The authors should highlight the contributions of their work in the form of a list at the end of the introduction. Please refer to any high-level paper to correct this problem.
8. All references, equations, figures, tables, sections, etc. appearing in the manuscript should be hyperlinked to facilitate readers' reading.
9. Some mathematical symbols are not italicized, such as the mathematical symbols in Table 1.
10. It is recommended that at the beginning of each section, the content of the section be briefly introduced with several sentences.
11. The mathematical symbols in Figures 2 and 3 are also not italicized.
12. The Conclusions section does not meet the requirements. The authors should present current problems, solutions, contributions, findings, limitations, and prospects for future work in a more engaging manner.
13. The information in the "Author Contributions" section is clearly incomplete. Please refer to any high-level paper to correct this problem.
14. There are many problems with the format of the references, and they clearly do not meet the requirements.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
