A wireless sensor network (WSN) is used in many sectors (such as health, banking, government ... etc.) to collect data for a specific environment. This data should be protected from hacking, any modification, deletion, or interception of this data that could cause catastrophic results. Therefore, the use of technologies such as Steganography is important in protecting data in the form of images. This topic is very important and hot in the field of networking applications. The authors proposed a context of applications with concrete examples and validated via simulation results. They provided some details on Steganography and Steganalysis. Also, they accurately indicated the difference between Steganography and Cryptography. However, the authors should address all of our concerns to improve search quality.

Comments on abstract, title, references

. The authors should clearly state the aims of the study and provide a description of the gap in the knowledge and the need to conduct this study. . In the abstract, the authors should indicate briefly the study findings. Additionally, the abstract is incomprehensive (The authors should explain briefly purpose/significance, method/process and result/conclusion) and dependent (The abstract should be entirely understandable (self-contained text) on its own to a reader who has not read the whole article/associated research). . The title is relevant but is not informative. It should improve the paper title. We suggest “Data authentication of wireless sensor network based on hiding techniques: A review”. . All the references are relevant. References are not recent in relation to the year of publication of the research, 11 references are outdated, some of the references are not written correctly, some references do not contain enough information, the references list does not contain a single format. Appropriate key studies are not included, the number of references is insufficient for this study.

Comments on introduction/background

. Although there is some information investigated (1 Introduction and 2 Steganography and Steganalysis) by the authors, the information provided in the introduction is not quite clear about the topic. For example, they indicated the benefit of information hiding techniques in sensor networks but did not explain that security could affect the performance of sensor networks. The authors did not base information in the introduction with solid research, they relied on only one research [3]. Moreover, the authors did not indicate types of steganography techniques. Therefore, the background on the topic was not presented correctly. The research objectives were not written correctly. We suggest that researchers list research objectives accurately and scientifically to make it easier for the reader to track and understand the research. The authors did not add constructive criticism to demonstrate the flaws in the existing research and the purpose of this study. The first paragraph in 2.2 section (page3) has a great contradiction. The authors did not explain why they were focused on the steganography for the gray-scale images. . The authors should define the research question for this study. The authors indicated that the information transmitted by the sensors required security techniques, but there was no precise question about hiding the information gathered by the sensors. The research question is justified given what is already known about the topic because any change (attacks/threats) in the data collected by the sensors will have negative effects in a certain environment such as Health, government, banking, ... etc.

Comments on methodology

. The process of subject selection is not clear because the methodology is unclear, there is no correlation between methodology sections. For instance, some sections’ titles are inappropriate/incorrect, such as Section 3 "Relations between images and WSN". . The authors listed some data hiding techniques such as Digital Watermarking without regulation or measurement, and the variables and parameters are not defined correctly or appropriately. . The study methods are not valid and reliable. The authors did not add algorithms, flowcharts, samples, methods, measurements or manners that clarify their choice or design of the technique for hiding data in wireless sensor networks. . There is not enough detail in order to replicate the study. Authors depended on brief summaries to complete methodology.

Comments on data and results

. The data is not presented in an appropriate way. Figures 1 and 2 do not add anything scientific for this paper. Figure 3 (a,b,c) is not explained correctly in-text and the figure is blurry/unclear. This paper does not contain any tables, as the tables can be an important way to clarify the results. In general, the results are not investigated correctly. . This search does not contain statistical results. I am not clear about what is a practically meaningful result.

Comments on discussion and conclusions

. The results are not discussed properly. The authors discussed minor aspects in section “4.2.3 Simulation protocol and results”, and there is no comprehensive and rigorous discussion. The authors did not add any comparisons (tables, figures or explanations) between their research and the existing research. Also, the authors did not indicate the strengths and weaknesses of their research, nor did they explain the limitations in their study. . The conclusion section should be carefully written. The authors did not explain to the reader what they concluded from this study. The authors only listed a set of sentences on the topic of the research. . The conclusions are not supported by references or results. . If the search is refined based on comments, they may opportunities to inform future research. Major points in the article which needs clarification, refinement, reanalysis, rewrites and/or additional information and suggestions for what could be done to improve the article.

1. The introduction section should be improved, there are no details of the study and there is no criticism of previous research to clarify the importance of the study
2. The structure and organization of the search should be improved, in particular the methodology. For instance, the authors should either add the literature review in the introduction or create a separate section (Related Work). We suggest moving Section 4 (page5) before Section 3 (page4), as the steganographic techniques for WSN should be demonstrated before using the images and then hidden in WSN traffic. The title in Section 4.2.1 (page6) is inappropriate. The sections titles 3 (page4) and 4.2 (page6) should be improved because they do not describe the content of the sections. Section 3 should contain more subsections. Section 4.2.3 (page9) should be a separate section (Section 5) that includes the results and simulation protocol. Also, the authors should add a discussion and analysis section (Section 6) to highlight the strengths and weaknesses for the proposed, then a conclusion in Section 7.
3. The authors should improve the results and discussion section by adding some comparisons to show the superiority of the research results. Also, the authors should correctly describe their conclusion from this study in the Conclusion section.
4. This paper requires proofreading to improve research writing and make it mistakes/typos free. For instance, the double quote should be removed for "sensory data image" (page1, Abstract). The term "WSN" repeated in the abstract twice. The paragraphs (pages1-2, Introduction) are not linked properly. The authors should remove unwanted spaces such as space between “%” and “40” (page9). There are many abbreviations that were used before the authors define it (such as HUGO (page3), RQP (page5), CC-PEV (page9), … etc.). The reference [13] is not used in-text. References are not arranged in-text correctly. Figure 2 is not used in-text, … etc.
5. The reference list should be updated by adding recent research (on data hiding techniques in wireless sensor networks). In addition, as mentioned in our previous comments, the list of references requires significant revision.
6. Figure 3 is unclear. The authors should redraw the figure while maintaining high resolution (page11), especially, Figure 3 is important because it represents the results of this study.