The systematic literature review includes data and conclusions from other writers that are analyzed about one or more predetermined research topics. This can be accomplished using a variety of research methodologies, including a systematic literature review. The criteria should be clearly outlined before the review is undertaken and the systematic review should adhere to a clearly defined process or plan.
Initially, a search methodology was created, then systematic searches were carried out by it. These searchers were guided by strings that were created by the determined study question. Afterward, all of the searches were categorized using a search method. Also, research publications were screened based on their title, abstract, and objectives as well as included based on their inclusion criteria.
2.4. Filtering
Filtering is the capability to significantly reduced the scope of the search and lesser the number of results returned makes methodological filters interesting. Following are the processes in filtering:
2.4.1. Title Based Filtering
Title-based filtering was the initial stage of the filtering process. All publications that did not address the issue at hand were removed from the databases that were chosen.
Figure 2 shows the title-based filtering. It clearly shows the number of research papers selected which are related to our research question. Total 34 papers were selected after title-based filtering.
2.4.2. Abstract Based Filtering
Abstract-based filtering was done in the second section. All of the chosen databases did not include any papers whose abstracts did not address the issue.
2.4.3. Objective Based Filtering
In the third part of filtering, we performed objective based filtering. All the papers that are irrelevant are filtered according to their objectives.
Figure 3 shows that the steps of how each phase is done step by step. The paper selected after title-based filtering is 34 afterwards the abstract based filtering was done. In the last the object-based filtering was done, 08 research studies selected as their objectives matched with the research question.
2.4.4. Technique-Based Filtering
In technique-based filtering, it involves using specific techniques or tools to filter, analyze, and interpret research data. It is a systematic and objective approach to analyzing research data, aimed at identifying relevant information and patterns.
The
Table 3 is shows about the techniques and different protocols used in the research papers. There are many techniques which are same like consensus algorithm and IPFS because of the blockchain technology.
The research work of [
4] presents a novel approach to secure data sharing in a decentralized environment. The authors propose a protocol that combines blockchain technology and decentralized storage to achieve secure and efficient data sharing. One of the strengths of the paper is its clear and concise presentation of the proposed Meta-Key protocol. The authors provide a detailed description of the protocol, including its key components, such as the meta-key management mechanism and the data access control mechanism. They also explain how the protocol can be used to ensure secure data sharing in various scenarios, such as data sharing among different organizations.
The [
5] focuses on secure storage and access of electronic medical records (EMRs) using blockchain and IPFS (InterPlanetary File System) technology. The authors propose a secure and efficient method of storing and accessing EMRs, which ensures data confidentiality, integrity, and availability. They propose a four-layered architecture consisting of a data layer, a blockchain layer, a storage layer, and an access layer to achieve secure storage and access of EMRs.
The authors then provide a detailed description of each layer of their proposed architecture and the various mechanisms employed to ensure security and efficiency. They also provide a performance evaluation of their proposed system and compare it with existing approaches.
The study [
6] provides a comprehensive taxonomy for blockchain-based distributed storage technologies, which is a highly relevant and timely topic given the growing interest and adoption of blockchain technology in various domains. The paper starts by providing an overview of the state-of-the-art in blockchain-based distributed storage technologies, highlighting the different approaches and architectures used by various systems. The authors then propose a taxonomy for categorizing these systems, which consists of six main categories: 1) Data Access Mechanisms, 2) Consensus Mechanisms, 3) Security Mechanisms, 4) Storage Mechanisms, 5) Performance Metrics, and 6) Application Domains.
The [
7] presents an interesting study that proposes a novel approach for secure event storage in vehicular ad-hoc networks (VANETs). The authors propose the use of blockchain and interplanetary file system (IPFS) technologies to ensure secure and decentralized storage of event data, while also incorporating an authentication protocol to prevent unauthorized access. It explains the importance of event data in VANETs and the need for secure and reliable storage solutions.
Moreover, the authors then provide a brief overview of blockchain and IPFS technologies, highlighting their benefits and limitations. The proposed system architecture is then presented, which includes the use of blockchain-based smart contracts and IPFS for event storage and retrieval, and an authentication protocol based on digital signatures.
The authors conducted a simulation-based performance evaluation of their proposed system and compared it with a traditional centralized event storage solution. The results demonstrate the effectiveness of the proposed approach in terms of security, reliability, and scalability. The paper also includes a discussion of the limitations and future research directions.
The [
8] proposed the decentralized storage systems, such as InterPlanetary File System (IPFS), to store and retrieve data in a decentralized manner. This helps to ensure that data is stored securely and can be accessed by authorized parties only. They also used use consensus mechanisms, such as proof of work or proof of stake, to ensure the validity and consistency of the blockchain-based cloud storage system. This helps to prevent malicious attacks and ensures that the data stored in the system is secure and reliable.
The [
9] worked on novel blockchain-based solution for secure storage and sharing of Massive Open Online Courses (MOOCs) learning materials. The paper aims to address the security and privacy concerns associated with traditional MOOCs platforms by leveraging blockchain technology using the consensus algorithm.
The paper shows its innovative solution to a pressing problem in the field of MOOCs. The MOOCsChain scheme offers several advantages over traditional MOOCs platforms, such as improved security, privacy, and transparency. The authors provide a detailed description of the architecture and design of the MOOCsChain scheme, highlighting the different components and their functions.
This paper [
10] proposes the challenges of centralized cloud storage, such as the risk of data breaches and the high costs of storage and maintenance. The authors then propose their solution of decentralized cloud storage using blockchain and explain how it works. They describe the architecture, which includes a network of nodes that store data in a distributed manner and use blockchain for data authentication and access control.
The authors also provide a detailed analysis of the performance and security of their proposed system through simulations and experiments. The results show that their approach is highly efficient and secure, with low latency and high throughput. The proposed system provides several benefits, including security, privacy, and efficiency, and the performance evaluation demonstrates its effectiveness. With some improvements in the areas mentioned above, this paper has the potential to be a significant reference in the field of decentralized cloud storage using blockchain technology.
In the proposed system of [
11] provides an interesting solution for the problem of verifying data consistency in decentralized cloud storage systems. The authors propose the use of a blockchain-based consensus algorithm to verify the consistency of data stored across multiple nodes in a decentralized cloud storage system.
The authors present the proposed solution, which involves the use of a blockchain-based consensus algorithm to verify the consistency of data stored across multiple nodes in a decentralized cloud storage system. The proposed algorithm uses a distributed ledger to store a record of all transactions in the system, which allows for easy verification of data consistency. They provide a detailed description of the proposed algorithm and explain how it can be implemented in a decentralized cloud storage system. The authors also present simulation results that demonstrate the effectiveness of the proposed algorithm in ensuring data consistency.
Table 4 present the objectives of the research papers that were identified and their top priority to achieve these targets. These categories include data consistency, scalability, reliability, efficiency and data security.
There are many techniques like IPFS and Consensus protocol which are commonly used is in the research studies. Consensus protocol includes the multiple protocols like proof of work or proof of stake were being used. In addition to that there is a hash table used in almost every selected article in order to get the blockchain based secure environment system.
The
Table 4.1 also shows the techniques and methods used in these research studies. It clearly defines the common protocols and processes used in different research articles to gain the objectives.
2.6. Critical Review
The paper [
4] presents an interesting and innovative approach to secure data sharing in a decentralized environment. The authors use a series of experiments to demonstrate the efficiency and security of the Meta-Key protocol. The experiments show that the protocol can achieve fast data access while ensuring data security and confidentiality.
However, there are also some limitations to the paper. One potential limitation is that the proposed protocol relies heavily on the blockchain technology, which may not be practical in all scenarios. As they rely on secret keys to encrypt and decrypt the data, which can be difficult to manage and secure. If the keys are lost or stolen, the data may become inaccessible or compromised. Additionally, the paper does not address the scalability issues that may arise when using a blockchain-based decentralized storage architecture. [
12]
The Meta-Key protocol proposed by the authors shows great potential for practical applications, and the thorough evaluation of the protocol adds credibility to the research. However, further research is needed to address the limitations of the protocol and to explore its potential applications in different scenarios.
The research paper [
5] presents a comprehensive and well-structured approach to secure storage and access of EMRs using blockchain and IPFS technology. The proposed architecture appears to be well-designed, with various security mechanisms to ensure confidentiality, integrity, and availability of data. The performance evaluation also indicates that the proposed system is efficient and can handle a large volume of data.
Though, there are some limits of the research paper that need to be addressed. First, the authors do not provide a detailed discussion of the potential challenges associated with the adoption and implementation of their proposed system in real-world healthcare settings. Second, the authors do not provide a thorough discussion of the potential privacy concerns associated with the use of blockchain technology for EMR storage.
The decentralized nature of IPFS can make it challenging to manage and govern the network, which could impact its long-term viability and sustainability. This could potentially lead to issues such as governance disputes, network fragmentation, and lack of accountability. Since IPFS relies on the availability of network nodes to provide content, there is a risk that content may not be available if nodes hosting the content go offline or become unavailable. This could potentially impact the accessibility of important data or information. [
13]
The [
6] paper's strengths lie in its comprehensive coverage of the topic and its clear and well-organized taxonomy, which provides a useful framework for researchers and practitioners interested in blockchain-based distributed storage technologies. The taxonomy is well-structured, and the authors provide a detailed description of each category, highlighting the key features and characteristics of each.
But the paper also has some boundaries that need to be addressed. One of the limitations is that the authors do not provide a detailed evaluation of the different systems or technologies discussed in the paper. While the taxonomy is useful, it would have been more beneficial if the authors had included a critical evaluation of the different approaches, highlighting the strengths and weaknesses of each.
Furthermore, the paper does not discuss some of the more recent developments in the field, such as the emergence of decentralized storage networks (DSNs), which represent a promising alternative to traditional blockchain-based distributed storage systems. Including such developments would have provided a more complete picture of the state-of-the-art in blockchain-based distributed storage technologies. As different blockchain-based storage solutions have their own protocols and standards, it can be difficult to transfer data between different systems. This can limit the usefulness of these technologies for applications that require data sharing and collaboration between multiple parties. [
14]
Overall, [
6] is a valuable contribution to the field of blockchain-based distributed storage technologies. It provides a comprehensive taxonomy that can serve as a useful framework for researchers and practitioners, although it could have been strengthened by providing a more detailed evaluation of the different systems and including more recent developments in the field.
The paper [
7] provides a well-researched and well-presented approach for secure event storage in VANETs. The use of blockchain and IPFS technologies is a novel and effective solution to the challenges of secure and decentralized event storage. The authors' simulation-based evaluation provides empirical evidence of the effectiveness of their proposed system. However, the study could benefit from more comprehensive real-world experiments to validate the results further.
One area where the paper could be improved is in its clarity of presentation. Some of the technical details are not adequately explained, making it challenging for readers without an in-depth knowledge of the subject matter to understand fully. Additionally, the paper could benefit from more detailed discussions of the limitations of the proposed system and potential future research directions.
In conclusion, we can say that it is a valuable contribution to the field of secure event storage in VANETs. The proposed approach is innovative, and the simulation-based evaluation provides evidence of its effectiveness. With some improvements in clarity of presentation and more extensive experimentation, this paper has the potential to be a significant reference in this field.
In [
8] the author examines the various challenges associated with decentralized storage, including issues related to data privacy, security, and scalability. The author presents a balanced view of the challenges and benefits of decentralized storage solutions and suggests ways to mitigate these challenges.
The article could benefit from more detailed discussion of potential drawbacks or limitations of the proposed architecture. For example, the article briefly mentions that the use of blockchain technology could result in slower processing times and higher energy consumption, but it does not go into detail on how these issues could be addressed. Additionally, the article could provide more information on the potential challenges of implementing such a decentralized architecture in practice. Some consensus protocols, such as proof of work, can be slow and require a lot of computational power to function. This can result in slower transaction times and higher energy consumption. PFS is still a relatively new technology, and its network currently has limited bandwidth. This can result in slow download times and lower performance compared to traditional centralized systems.
Moreover, it provides a comprehensive overview of decentralized storage solutions, their benefits and challenges, and offers insightful analysis and evaluation of each type of solution. The article is a valuable resource for anyone interested in understanding the potential of decentralized storage solutions and their applications.
The paper [
9] presents an innovative solution to the security and privacy concerns associated with traditional MOOCs platforms. However, the paper has several limitations that need to be addressed. One of the limitations is the lack of evaluation of the proposed solution. While the authors provide a detailed description of the MOOCsChain scheme, they do not provide any experimental results or performance evaluation of the system. This makes it difficult to assess the practicality and effectiveness of the proposed solution.
Furthermore, the authors do not discuss the potential scalability issues associated with blockchain-based solutions. MOOCs platforms typically serve a large number of users, and blockchain-based solutions may not be able to handle the scale and performance requirements. The authors could have provided more insights into how the MOOCsChain scheme addresses these scalability issues. Nevertheless, the lack of evaluation and discussion on scalability issues limits the practicality and effectiveness of the proposed solution.
The paper [
10] presents an innovative solution for decentralized cloud storage using blockchain technology. The authors' approach offers several benefits, including data privacy, security, and efficiency. The performance evaluation demonstrates the effectiveness of the proposed system in terms of scalability, reliability, and security.
However, the paper could be improved in several areas. Firstly, the authors could have provided more detailed information about the challenges of centralized cloud storage and the limitations of existing solutions. Secondly, the paper could benefit from a more comprehensive discussion of the potential limitations and drawbacks of the proposed system, including the scalability and cost of running a large-scale decentralized storage network.
Additionally, the paper could be improved by providing more detailed technical information on the implementation of the proposed system. While the paper provides a good high-level overview of the architecture, it could be difficult for readers without a deep technical background to understand the implementation details.
The paper [
11] provides a detailed overview of the proposed blockchain-based consensus checking mechanism, which involves creating a decentralized network of nodes that can validate data and ensure its authenticity. The mechanism employs a combination of smart contracts, cryptographic algorithms, and blockchain technology to achieve consensus among the nodes.
One notable limitation of the paper is that it assumes a certain level of familiarity with blockchain technology, which may be challenging for readers who are not well-versed in the field. It would have been useful for the authors to discuss the scalability of the proposed algorithm and how it might perform in larger, more complex cloud storage systems. Another limitation of consensus protocols is their vulnerability to attacks. For example, in a Proof of Work protocol, an attacker with a significant amount of computational power can perform a 51% attack, which can compromise the integrity of the system. Similarly, in a Proof of Stake protocol, an attacker with a significant amount of stake can perform a similar attack. [
15]
Additionally, the paper only focuses on the consensus checking mechanism and does not provide an in-depth analysis of other aspects of cloud storage systems, such as data privacy or security. The author could have explored alternative consensus algorithms and compared their effectiveness to the proposed blockchain-based solution.
Overall, the article presents an interesting solution to the problem of data consistency in decentralized cloud storage systems. While there are some limitations to the paper, the proposed algorithm is well-described and appears to be effective in ensuring data consistency.