Attack-Aware Security Function Chaining

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article discusses attack-aware security function chaining. The article introduces placing security functions that can defend against ongoing attacks early in the security service function chain (SSFC) so that they can drop malicious packets and prevent them from creating resource requirements on subsequent security functions in the chain. To implement this approach, the article proposes a central instance called Function Chaining Controller (FCC), which is responsible for the ordering of security functions. The FCC needs to understand the traffic passing through the security functions and the number of attacks detected. To this end, the security function wrapper deployed with the security function reports the number of attacks detected by a specific function to the FCC. The article also introduces performance modeling and analysis, analyzing the impact of different SSFC orders on performance. The article also proposes an attack-aware dynamic SSFC reordering framework that is based on previous knowledge and verified by simulating attack patterns. However, the paper still has the following problems:

 

What types of attacks and security functions does this paper discuss?

How do they interact?

 

How does the FCC change the network routing configuration based on reports of attacks on security functions?

Is this approach to dynamic routing configuration effective?

 

When calculating the optimal sequence of the security function chain, how do you determine the resource requirements of each security function?

Is this approach applicable to complex security systems?

 

Could the authors provide more detailed implementation instructions or code to facilitate the reproduction of their study?

 

How does the proposed method perform under different network conditions or attack types, and are there any specific limitations to its applicability?

 

What additional measures could be taken to ensure the robustness and reliability of the experimental results?

 

How does the proposed framework compare with existing solutions in terms of performance, scalability, and resource efficiency?

 

Can the authors clarify any complex sections or concepts that may be difficult for readers to understand?

 

Are there any plans for future work to address the limitations identified in the paper or to extend the framework's capabilities?

Author Response

Comments 1: What types of attacks and security functions does this paper discuss? How do they interact?
Answer 1: The types and attacks are extensively described in Section 5 "Effect of the Security Service Function Chain Order". We added a short list of the types in the introduction.

Comments 2: How does the FCC change the network routing configuration based on reports of attacks on security functions?
Answer 2: The FCC uses an SDN controller to change this order. The concept is already described in the introduction as well as in Section 7 "Attack-aware Security Service Function Chain Reordering Framework".

Comments 3: Is this approach to dynamic routing configuration effective?
Answer: The effectiveness of changing the routes is already discussed in Section 5 "Effect of the Security Service Function Chain Order". The effectiveness of the Framework is discussed in the framework's evaluation section.

Comments 4: When calculating the optimal sequence of the security function chain, how do you determine the resource requirements of each security function?
Answer 4: The security functions are modelled as branch actions with different behavior (including resource demands) per branch. As described in Section 6, simple black box models allow for the calculation of the resource requirements.

Comments 5: Is this approach applicable to complex security systems?
Answer 6: As already described in section 6, depending on the complexity, different reordering strategies are possible.

Comments 6: Could the authors provide more detailed implementation instructions or code to facilitate the reproduction of their study?
Answer 6: We already provide the code for the wrappers, the fcc, the sdn controller and the virtualized evaluation environment. Please be more specific.

Comments 7: How does the proposed method perform under different network conditions or attack types, and are there any specific limitations to its applicability?
Answer 7: The performance under different attack types is extensively evaluated in Section 5, the performance of the framework is evaluated in section 7. We also discuss current shortcomings and the solutions to the remaining issues, depending on the requirements for the environment.

Comments 8: What additional measures could be taken to ensure the robustness and reliability of the experimental results?
Answer 8: The experiments were repeated multiple times. As one can see in many charts, we provide confidence intervals. These are always at levels, where we can say, that our results are significant. Therefore we see no need for aditional repetions. Other charts are examplary to show certain behaviours that were observed during our experiments.

Comments 9: How does the proposed framework compare with existing solutions in terms of performance, scalability, and resource efficiency?
Answer 9: To our knowledge, there are no openly available frameworks to attack-aware function chain reordering. In Table 1, we made a theoretical comparison between an optimized function chain and a non-optimized function chain. Whether the number of instances per security function is determined through reactive scaling or through modeling the resource demand is not relevant for the applicability of dynamic reordering.

Comments 10: Can the authors clarify any complex sections or concepts that may be difficult for readers to understand?
Answer 10: Please point to the sections, that you consider difficult to understand.

Comments 11: Are there any plans for future work to address the limitations identified in the paper or to extend the framework's capabilities?
Answer 11: As described in the future work section at the end, we plan to have a more fine-grained SSFCs behavior. In the course of this possible extension, we might also realized one of the proposed solutions to the discussed framework limitations. However, from a pure research perspective, the validity and possible effect of the function chain reordering approach has been shown.

Reviewer 2 Report

Comments and Suggestions for Authors Despite that paper’s topic is relevant enough to the scope of the journal and its practical outcomes exhibit promising results, the paper should not be accepted in current form. It results with interesting findings and strong practical outcomes, but the quality of the text should be significantly improved before any further publication steps. There are several issues which have to be taken into account within the major revision of the paper:

1. The paper is too long and some of the parts are difficult to follow. The authors should really think of cutting the general descriptions and commonly known facts in order to make the paper shorter. 
2. Section/subsection split seems odd - there are too many short parts of the text grouped together, but not in a consistent way.
3. Future works section seems quite long 
4. Related works could potentially be sumamrized within a table, showcasing the main similar solutions, applied approaches, relevant use cases and the achieved results
5. Presentation quality of the paper should be improved. Despite that experimental part is comprehensive, it seems quite longer  compared to the rest of the paper and should be summarized in more compact way 

Comments on the Quality of English Language While the overall language quality is satisfiable and no major grammar issues are noticed, formulations should be stylistically improved. Some of the sentences either repeat the same phrases in a sequence and references to previous parts of the text or other elements from the same sentence are unclear in some parts. Avoid too many references to previous parts of the text or in a row within the same sentence, or possibly specify more precise the referenced elements. To sum up, minor stylistic aspects-related language improvements are needed across the text.

Author Response

Note: Some of your suggestions conflicted with suggestions from reviewer 3, who wanted us to extend sections, you suggest shorting. We tried to balance both requests carefully.

Comment 1: The paper is too long and some of the parts are difficult to follow. The authors should really think of cutting the general descriptions and commonly known facts in order to make the paper shorter. 
Answer 1: In the background section, we have cut multiple sentences (red [...]) and removed the SDN and NFV basics entirely.

Comment 2: Section/subsection split seems odd - there are too many short parts of the text grouped together, but not in a consistent way.
Answer 2: The shortening and the removal of several interim paragraphs should improve this situation.

Comment 3: Future works section seems quite long 
Answer 3: We shorted the section.

Comment 4: Related works could potentially be sumamrized within a table, showcasing the main similar solutions, applied approaches, relevant use cases and the achieved results
Answer 4: We are unsure on how to do this for the underlying related work. If the solutions were rather similar, this would be a fitting approach. However, this is not the case here.

Comment 5: Presentation quality of the paper should be improved. Despite that experimental part is comprehensive, it seems quite longer  compared to the rest of the paper and should be summarized in more compact way.
Answer 5: We merged multiple tables, replaced the CPU load figures with a summary in one of the merged tables and cut several paragraphs. This led to a reduction of multiple pages. However, we stand by the opinion, that an extensive measurement evaluation and its discussion is necessary.

Reviewer 3 Report

Comments and Suggestions for Authors

1. Introduction and Background

   - The introduction provides a comprehensive overview of the increasing frequency and severity of cyberattacks, effectively setting the stage for the proposed research on attack-aware Security Service Function Chain (SSFC) reordering. However, the section could benefit from a more detailed explanation of the limitations of current security function placements and a clearer justification for why dynamic reordering is a novel and necessary approach.

 

2. Literature Review

   - The literature review is thorough and covers relevant work in both NFV and SDN domains. It highlights the gaps in intelligent placement and performance optimization of security functions within SSFCs. To enhance this section, the authors should include a comparative analysis table summarizing the strengths and weaknesses of existing approaches relative to their proposed solution.

 

3. Methodology

   - The methodology is well-structured, detailing the framework's design, implementation, and evaluation. The use of Python for the proof-of-concept implementation is justified, but more technical details about the implementation challenges and how they were overcome would provide deeper insights. Additionally, the choice of metrics for evaluation (throughput, latency, packet loss) is appropriate, but the methodology section could elaborate more on why these particular metrics were selected and how they comprehensively capture the performance impacts of SSFC reordering.

 

4. Evaluation and Results

   - The evaluation section presents convincing evidence of the benefits of dynamic SSFC reordering through various experiments under different attack scenarios. The visualizations (Figures 23-26) effectively illustrate the changes in routing configurations and their impacts. However, the results discussion could be expanded to include more granular analysis of specific scenarios where the proposed reordering framework might underperform or face limitations. Also, discussing the statistical significance of the results would strengthen the findings.

 

5. Discussion

   - The discussion section addresses key functionality and security issues during reconfiguration, providing potential solutions. This critical reflection is valuable, but it would benefit from a more structured approach, such as categorizing the solutions based on their feasibility and impact. Additionally, integrating some real-world case studies or hypothetical scenarios to contextualize these issues and solutions would enhance the practical relevance of the discussion.

 

6. Conclusion and Future Work

   - The conclusion succinctly summarizes the paper's contributions and highlights the framework's benefits for data center operators and researchers. The future work section outlines promising directions, such as fine-grained traffic classification and automated model-learning for security functions. To improve this section, the authors should provide a more detailed roadmap or action plan for these future research directions, specifying the expected challenges and potential solutions.

 

 Suggestions for Authors

 

1. Clarify the Novelty and Contributions:

   - Clearly articulate the novel aspects of your approach compared to existing solutions. Highlight the specific contributions of your work in the introduction and throughout the paper to ensure that readers understand the significance of your research.

 

2. Expand Technical Details:

   - Provide more technical details on the implementation, especially the challenges faced and how they were addressed. This will offer valuable insights for researchers and practitioners looking to replicate or build upon your work.

 

3. Enhance Literature Review:

   - Include a comparative analysis table in the literature review to summarize the existing approaches and highlight the unique advantages of your proposed framework.

 

4. Detailed Methodology Justification:

   - Elaborate on the choice of evaluation metrics and explain how they comprehensively capture the performance impacts of SSFC reordering. This will strengthen the methodology section and provide a clearer rationale for your evaluation approach.

 

5. In-depth Results Analysis:

   - Expand the discussion of results to include more granular analysis and address potential limitations of your approach. Discuss the statistical significance of your findings to provide a more robust interpretation of the results.

 

6. Structured Discussion of Solutions:

   - Structure the discussion of security issues and solutions in a more organized manner, categorizing them based on feasibility and impact. Use real-world case studies or hypothetical scenarios to contextualize the discussion and enhance its practical relevance.

 

7. Future Work Roadmap:

   - Provide a detailed roadmap or action plan for future research directions, specifying expected challenges and potential solutions. This will offer a clear pathway for advancing the research and encourage further exploration in the field.

Comments on the Quality of English Language

Grammar and Syntax:

   - Overall, the paper is written in clear and understandable English. However, there are instances where sentence structure could be improved for better clarity. For example, in the sentence "Thus, especially for so-called Security Service Function Chains (SSFCs)—infrastructures chaining multiple network security functions behind each other—the dropping property creates a new level of complexity," the use of dashes makes the sentence cumbersome. Consider rephrasing it for better readability.

 

2. Consistency:

   - Ensure consistency in the use of terms and abbreviations. For instance, "Security Service Function Chains" should consistently be abbreviated as "SSFCs" throughout the document. Additionally, ensure that once an abbreviation is introduced, it is used consistently in place of the full term.

 

3. Technical Jargon:

   - While technical jargon is necessary in a specialized field like cybersecurity, ensure that terms are adequately explained when first introduced. For example, "DDoS" is explained, but terms like "NFV" and "SDN" should also have brief definitions or explanations upon first use.

 

4. Punctuation:

   - There are several areas where punctuation can be improved. For instance, in the sentence "Combined with the concurrent introduction of NFV, security appliances no longer need to be specialized hardware components, but instead, generic computing hardware can provide these capabilities," the comma after "instead" is unnecessary. Careful proofreading to correct such minor punctuation errors would enhance readability.

 

5. Flow and Coherence:

   - Some paragraphs, especially in the methodology and results sections, are dense with information and can be split for better flow. Breaking down complex sentences into simpler, more concise ones can help maintain the reader’s attention and improve comprehension.

 

6. Spelling:

   - Ensure that spelling is consistent with either American or British English throughout the document. For example, use "analyze" consistently instead of switching between "analyze" and "analyse."

 

7. Use of Articles:

   - There are instances where articles are missing or incorrectly used. For example, "The performance difference between the different orders is up to two orders of magnitude" could be rephrased to "The performance difference between different orders can be up to two orders of magnitude."

Author Response

Note: Some of your suggestions conflicted with suggestions from reviewer 2, who wanted us to short sections, you suggest extending. We tried to balance both requests carefully.

Comment: The introduction provides a comprehensive overview of the increasing frequency and severity of cyberattacks, effectively setting the stage for the proposed research on attack-aware Security Service Function Chain (SSFC) reordering. However, the section could benefit from a more detailed explanation of the limitations of current security function placements and a clearer justification for why dynamic reordering is a novel and necessary approach.
Answer 1: We added a corresponding sentence.

Comment 2: The literature review is thorough and covers relevant work in both NFV and SDN domains. It highlights the gaps in intelligent placement and performance optimization of security functions within SSFCs. To enhance this section, the authors should include a comparative analysis table summarizing the strengths and weaknesses of existing approaches relative to their proposed solution.
Answer 2: We are unsure on how to do this for this example, since the discussed works do not solve the same problem. If we presented an alternative security function chain reordering framework to an existing solution, this would be an appropriate strategy.

Comment 3: The methodology is well-structured, detailing the framework's design, implementation, and evaluation. The use of Python for the proof-of-concept implementation is justified, but more technical details about the implementation challenges and how they were overcome would provide deeper insights. Additionally, the choice of metrics for evaluation (throughput, latency, packet loss) is appropriate, but the methodology section could elaborate more on why these particular metrics were selected and how they comprehensively capture the performance impacts of SSFC reordering.
Answer 3: This conflicts with the comments from Reviewer 2 to cut basic knowledge from the paper. We consider especially throughput and latency to be THE basic software engineering metrics. Loss rate is also a typical netwok QoS metric.

Comment 4: The evaluation section presents convincing evidence of the benefits of dynamic SSFC reordering through various experiments under different attack scenarios. The visualizations (Figures 23-26) effectively illustrate the changes in routing configurations and their impacts. However, the results discussion could be expanded to include more granular analysis of specific scenarios where the proposed reordering framework might underperform or face limitations. Also, discussing the statistical significance of the results would strengthen the findings.
Answer 4: Again, this conflicts with the suggestion to significantly shorten the evaluation section. We think, the different scenarios are sufficiently analyzed. However, we agree that a statistical evaluation of the significance of our edge-cases would be relevant but performing these experiments and evaluating the results was not feasible in the short revision timeframe.

Comment 5: The discussion section addresses key functionality and security issues during reconfiguration, providing potential solutions. This critical reflection is valuable, but it would benefit from a more structured approach, such as categorizing the solutions based on their feasibility and impact. Additionally, integrating some real-world case studies or hypothetical scenarios to contextualize these issues and solutions would enhance the practical relevance of the discussion.
Answer 5: We added an overwiew table for the proposed solutions. We consider the real-world case-studies future work and hope to execute them with our industry partners.

Comment 6: The conclusion succinctly summarizes the paper's contributions and highlights the framework's benefits for data center operators and researchers. The future work section outlines promising directions, such as fine-grained traffic classification and automated model-learning for security functions. To improve this section, the authors should provide a more detailed roadmap or action plan for these future research directions, specifying the expected challenges and potential solutions.
Answer 6: This conflicts with reviewer 2's suggestion to shorten this section. However, the main challenge - as often - would be to find motivated students that want to contribute to this topic with their theses.

Comment 7: Clearly articulate the novel aspects of your approach compared to existing solutions. Highlight the specific contributions of your work in the introduction and throughout the paper to ensure that readers understand the significance of your research.
Answer: We added/summarized several sections to make them more pointy and concise.

Comment 8: Provide more technical details on the implementation, especially the challenges faced and how they were addressed. This will offer valuable insights for researchers and practitioners looking to replicate or build upon your work.
Answer 8: We extracted major parts to the linked github repositories. This seems to also fit with the suggestions of reviewer 2. We currently look for a student to setup an end-to-end solution to attain artifact quality level.

Comment 9: Include a comparative analysis table in the literature review to summarize the existing approaches and highlight the unique advantages of your proposed framework.

Comment 10: Elaborate on the choice of evaluation metrics and explain how they comprehensively capture the performance impacts of SSFC reordering. This will strengthen the methodology section and provide a clearer rationale for your evaluation approach

Comment 11: Expand the discussion of results to include more granular analysis and address potential limitations of your approach. Discuss the statistical significance of your findings to provide a more robust interpretation of the results.

Comment 12: Structure the discussion of security issues and solutions in a more organized manner, categorizing them based on feasibility and impact. Use real-world case studies or hypothetical scenarios to contextualize the discussion and enhance its practical relevance.

Comment 13: Provide a detailed roadmap or action plan for future research directions, specifying expected challenges and potential solutions. This will offer a clear pathway for advancing the research and encourage further exploration in the field.

Answers 9-13: See previous replies.

Comment 14: Overall, the paper is written in clear and understandable English. However, there are instances where sentence structure could be improved for better clarity. For example, in the sentence "Thus, especially for so-called Security Service Function Chains (SSFCs)—infrastructures chaining multiple network security functions behind each other—the dropping property creates a new level of complexity," the use of dashes makes the sentence cumbersome. Consider rephrasing it for better readability.
Answer 14: done

Comment 15: Ensure consistency in the use of terms and abbreviations. For instance, "Security Service Function Chains" should consistently be abbreviated as "SSFCs" throughout the document. Additionally, ensure that once an abbreviation is introduced, it is used consistently in place of the full term.
Answer 15: Please name an inconsistent use of SSFC(s). Our abbreviation framework should take care of introducing abbreviations. However, in some cases (like captions) we decide to use the longform on purpose.

Comment 16: While technical jargon is necessary in a specialized field like cybersecurity, ensure that terms are adequately explained when first introduced. For example, "DDoS" is explained, but terms like "NFV" and "SDN" should also have brief definitions or explanations upon first use.
We simplified the description of SDN and NFV and added a summarizing sentence in the introduction.

Comment 17: There are several areas where punctuation can be improved. For instance, in the sentence "Combined with the concurrent introduction of NFV, security appliances no longer need to be specialized hardware components, but instead, generic computing hardware can provide these capabilities," the comma after "instead" is unnecessary. Careful proofreading to correct such minor punctuation errors would enhance readability.
Answer 17: We cut the corresponding sentence. However, we found that the necessity of commas can be a religious matter. Also, different grammar checkers often disagree.

Comment 18: Some paragraphs, especially in the methodology and results sections, are dense with information and can be split for better flow. Breaking down complex sentences into simpler, more concise ones can help maintain the reader’s attention and improve comprehension.
Answer 18: We shorted/cut/split/rephrased multilpe paragraphs and sentences.

Comment 19: Ensure that spelling is consistent with either American or British English throughout the document. For example, use "analyze" consistently instead of switching between "analyze" and "analyse."
Answer: We did not find any occurences of "analyse" except for the conflicts of interest statment.

Comment 20: There are instances where articles are missing or incorrectly used. For example, "The performance difference between the different orders is up to two orders of magnitude" could be rephrased to "The performance difference between different orders can be up to two orders of magnitude."
Answer 20: Change some occurences. Especialy the specific occurance.

Reviewer 4 Report

Comments and Suggestions for Authors

The authors raise a very interesting topic related to security and specifically to the proposed solution to increase this security.

The authors present well in the Introduction the reasons for which they dealt with the subject. They actually refer to appropriate literature sources. In the further part they also include a chapter on Related Works in which they refer to research by other teams.

At the beginning, the authors present some foundations necessary for introducing the topic and facilitating the understanding of the proposed solution. They describe various aspects related to it. They present various solutions.

Sequentially and exhaustively, an analysis of the authors' solution is presented, supported by appropriate drawings that help in the perception of the solution.
Importantly, the authors also present the implementation of the idea, which facilitates the verification of the usefulness of their idea in practice in real conditions and not only simulation or analytical ones.
The included tests show the authors' solution to be promising.
An undoubted advantage is the inclusion of an extensive discussion in which the authors show the proper scientific approach to the subject.
The whole thing is crowned by extensive conclusions.

Author Response

Thank you for the positive review.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The paper has been revised appropriately, but the following issues should be addressed:

 

There is an unknown red symbol before the introduction of the paper, which is puzzling.

 

The last period after the sentence in RQ1 should be deleted. Please check carefully.

 

The sentence in the introduction, "In recent years, cybersecurity has come to the attention of the general public." lacks context and needs to cite the latest relevant papers, such as "Image privacy protection scheme based on high-quality reconstruction DCT compression and nonlinear dynamics"

 

The sentence "and we propose additional extensions to eliminate the remaining shortcomings." is grammatically correct, but "shortcomings" could be replaced with "deficiencies" for a more formal tone.

 

In the introduction, the phrase "cybersecurity has come to the attention of the general public" could be rephrased for clarity to "cybersecurity has become a concern for the general public."

 

The sentence "For the United States of America alone, losses increased by 25, 773 % from $485, 000, 000 in 2011 to $12, 500, 000, 000 in 2024." has a typo with extra spaces before and after the percentage value. It should be "25,773%".

 

In the sentence "These deficiencies make IoT devices an easy target for cybercriminals who aim to take over the control of such devices," consider removing "over" for a more natural phrasing: "These deficiencies make IoT devices an easy target for cybercriminals who aim to take control of such devices."

 

The sentence "The increasing importance of cybersecurity, combined with the loss of the ability to counter these threats by replacing used hardware every few years, creates a motivation to find ways to use available resources more efficiently." is grammatically correct but could be rephrased for better readability: "The growing importance of cybersecurity, coupled with the diminishing ability to counter threats by regularly replacing hardware, motivates the search for more efficient use of available resources."

Author Response

Comment 1: There is an unknown red symbol before the introduction of the paper, which is puzzling.
Answer 1: This cannot be reproduced at our end.

Comment 2: The last period after the sentence in RQ1 should be deleted. Please check carefully.
Answer 2: Done

Comment 3: The sentence in the introduction, "In recent years, cybersecurity has come to the attention of the general public." lacks context and needs to cite the latest relevant papers, such as "Image privacy protection scheme based on high-quality reconstruction DCT compression and nonlinear dynamics"
Answer 3: The following sentences elaborate on this statement and give the necessary references. We consider the suggested paper more as a proof of attention by the scientific community than from the public.

Comment 4: The sentence "and we propose additional extensions to eliminate the remaining shortcomings." is grammatically correct, but "shortcomings" could be replaced with "deficiencies" for a more formal tone.
Answer 4: Done.

Comment 5: In the introduction, the phrase "cybersecurity has come to the attention of the general public" could be rephrased for clarity to "cybersecurity has become a concern for the general public."
Answer 5: We found an even more concise wording.

Comment 6: The sentence "For the United States of America alone, losses increased by 25, 773 % from $485, 000, 000 in 2011 to $12, 500, 000, 000 in 2024." has a typo with extra spaces before and after the percentage value. It should be "25,773%".
Answer 6: ISO 31-0 requires the space.

Comment 7: In the sentence "These deficiencies make IoT devices an easy target for cybercriminals who aim to take over the control of such devices," consider removing "over" for a more natural phrasing: "These deficiencies make IoT devices an easy target for cybercriminals who aim to take control of such devices."
Answer 7: We made a change similar to the suggested one.

Comment 8: The sentence "The increasing importance of cybersecurity, combined with the loss of the ability to counter these threats by replacing used hardware every few years, creates a motivation to find ways to use available resources more efficiently." is grammatically correct but could be rephrased for better readability: "The growing importance of cybersecurity, coupled with the diminishing ability to counter threats by regularly replacing hardware, motivates the search for more efficient use of available resources."
Answer 8: We accepted the suggestion.

Reviewer 2 Report

Comments and Suggestions for Authors

Most of the comments were adopted, except for the one about summarizing related works. The work was shortened and a little easier to follow, the most relevant aspects and consolidated information were emphasized. However, further reducing the length and improving the quality of the presentation is still recommended with the goal of keeping the length of the paper below 40 pages if possible. At this point, despite the efforts of the author, the paper is still quite long.

Author Response

Comment 1: Most of the comments were adopted, except for the one about summarizing related works. The work was shortened and a little easier to follow, the most relevant aspects and consolidated information were emphasized. However, further reducing the length and improving the quality of the presentation is still recommended with the goal of keeping the length of the paper below 40 pages if possible. At this point, despite the efforts of the author, the paper is still quite long.
Answer 1: We did some minor figure adjustments and got it down to 42 pages. Since another accepted paper is 49 pages, we deem the length to be acceptable.