A Blockchain-Based Access Control System for Secure and Efficient Hazardous Material Supply Chains

Abstract

With the rapid expansion of global trade, the complexity and diversification of supply chains have become increasingly significant. In particular, the supply chain for hazardous materials, involving chemicals and explosives, requires stringent regulation. Managing the flow of these high-risk goods necessitates a reliable access control system to ensure safety and compliance. Traditional supply chain management systems often rely on centralized databases and record-keeping systems, which are prone to tampering and single points of failure, making them inadequate for current high-security demands. This paper combines blockchain technology with a hazardous materials supply chain model. In the blockchain network, our innovation lies in the introduction of a transaction coordinator to create transaction sets for each supply chain entity along with smart contracts to implement access control for these transaction sets. We also propose a new hazardous materials supply chain model architecture and conduct experimental verification using simulated hazardous materials supply chain data. Our experimental results show that the proposed method performs excellently in throughput and latency tests, demonstrating the potential to enhance the efficiency and security of supply chain management.

1. Introduction

The blockchain concept was first proposed by Satoshi Nakamoto in the paper titled “Bitcoin: A Peer-to-Peer Electronic Cash System” [1], which detailed the operational principles of Bitcoin and the fundamental principles of blockchain technology. Blockchain is a distributed ledger technology characterized by its tamper-resistance, decentralization, immutability, and traceability, and is considered a revolutionary technological innovation. The development of blockchain technology has promoted advancements in various fields, including supply chain management [2], digital identity [3], healthcare [3,4], and the Internet of Things (IoT) [3,5]. Blockchain has become a key tool for managing shared data in applications where there is no universally recognized trusted center to store and manage all data as well as in scenarios where data records need to be formed through consensus among organizations that do not fully trust each other. In cryptocurrency applications, in order to prevent double-spending attacks it is necessary for all users to verify transactions on the ledger to ensure the transparency of the blockchain ledger. However, in subsequent application scenarios there are often cases where the information stored on the chain is sensitive and should not be accessed by unauthorized users. For example, in the financial industry [6], cross-border transactions, and large fund transfers, only authorized users should have access to sensitive data. Blockchain can ensure that only banks and financial institutions with the corresponding permissions can access transaction records. By setting fine-grained permission policies, blockchain platforms can customize access rights for different levels of users from ordinary employees to senior management, ensuring that each person can only access the information they are authorized to view. Such access control both enhances internal security and ensures compliance with global financial regulatory requirements, providing both compliance and transparency of transactions. Therefore, in such cases blockchain systems need to be designed so as to ensure that only users with the appropriate permissions can access sensitive information through access control mechanisms.

In modern society, in addition to the abundant hazardous materials found in nature, increasingly complex industrial supply chains have also led to the creation of many new hazardous materials by manufacturing units [7]. Hazardous materials have become deeply integrated into people’s daily lives, playing indispensable roles in many aspects. From cooking, cleaning, transportation, and personal care to energy supply, their use provides convenience and efficiency for our daily activities. However, due to improper management of hazardous materials supply chains and a lack of safety awareness, data from the Chemical Incident Tracker website indicates that there are on average no fewer than 20 accidents related to hazardous materials in the United States each month. These accidents result in approximately 300 injuries and 10 deaths annually, causing the evacuation of people, road closures, and disruptions to normal life [8]. These accidents can pose risks to nearby schools, hospitals, and other institutions. By integrating blockchain technology with access control mechanisms, the management of hazardous materials supply chains can be enhanced. This approach aims to improve the transparency, security, and controllability of the hazardous materials supply chain, providing a safer and more reliable solution for managing these supply chains while also reduces the likelihood of accidents and mitigating their negative impact on society.

Unlike other supply chains, such as those for food [9] and pharmaceuticals [10], the hazardous materials supply chain should focus on safety and compliance. As an example, the hazardous materials supply chain shown in Figure 1 includes one raw material supplier, two manufacturers, one sales company, two transportation companies, and end-users such as construction units and energy production units. Each entity in the hazardous materials supply chain stores information about the hazardous materials they handle or transport. We use a transaction set (TXset) to store the transaction information of these hazardous materials. As this hazardous materials supply chain lacks a trusted single entity to manage data, the relevant information is stored on a blockchain. Using blockchain technology in hazardous materials supply chain management can significantly enhance the security, transparency, and efficiency of the supply chain, while reducing operational costs and enabling automated management. These advantages help to overcome the shortcomings of traditional supply chain management systems, providing robust support for the safe management of hazardous materials. Due to the requirements of certain countries and governments, this information cannot be freely disseminated, making the addition of an access control function necessary. The transaction information of the hazardous materials supply chain is encrypted and stored on a blockchain, with strict access control measures implemented for the transaction information. This not only enhances the level of data security and privacy protection but also improves the transparency and trustworthiness of the system, ensuring that sensitive information flows securely in a highly controlled environment [11]. The granting or revoking of access rights to a specific TXset is performed by authorized users. In traditional access control, a central system is usually responsible for enforcing access control policies. Notably, as data immutability is a core characteristic of blockchains, i.e., data cannot be modified or deleted after being recorded, it is challenging to implement revocation of permissions for authorized users.

Our contributions mainly include the following:

• We propose a structural model for the hazardous materials supply chain.
• We implement an access control model suitable for hazardous materials supply chains on the blockchain.
• We implement a hazardous materials supply chain data simulator that can generate supply chain data, and conduct benchmarking on Hyperledger Fabric.

2. Related Work

2.1. Applications of Blockchain in Supply Chain Management

Several studies have applied blockchain technology to supply chain management. In the pharmaceutical sector, Ghadge et al. [12] proposed a conceptual framework for the use of blockchains in the pharmaceutical supply chain, analyzing applications in anti-counterfeiting, drug recall management, and patient privacy protection that provide theoretical foundations and practical guidance for the pharmaceutical industry. In the food sector, Shahid et al. [9] proposed a blockchain- and smart contract-based solution for the agrifood supply chain that utilizes the Ethereum network and IPFS for efficient and secure data storage. They explored traceability, transactions, delivery mechanisms, and reputation systems, and conducted performance and security analyses. In the hazardous materials sector, Oudani et al. [7] proposed a framework based on a green blockchain and the Internet of Things (IoT) aimed at enhancing the safety and traceability of the hazardous materials supply chain, ensuring data security, privacy, and transparency, and reducing energy consumption and carbon dioxide emissions. In past research on hazardous materials supply chains, the focus has mainly been on risk assessment frameworks for the supply chain and the planning of transportation routes. Rayas et al. [13] proposed a risk assessment model framework for the hazardous materials supply chain in Mexico, developing risk assessment models for each major segment of the closed-loop supply chain. The model uses proportional risk assessment techniques based on the National Fire Protection Association (NFPA) classification to calculate risk costs in hazardous materials management. By analyzing risk and cost, decision-makers can determine which activities should be outsourced to mitigate risk and comply with regulatory requirements. Xie et al. [14] explored the research on hazardous materials transportation route planning and proposed a multimodal hazardous materials transportation siting and route optimization model that uses a mixed-integer linear model to simultaneously optimize transfer station siting and transportation routes. Case studies validated the model’s effectiveness in reducing transportation risks and costs, and the study summarized its findings and future directions.

To ensure the procurement of high-quality raw materials that meet safety standards, hazardous materials supply chains must pay particular attention to safety and compliance at each stage. During the procurement phase, the quality and storage conditions of raw materials must be ensured in order to guard production safety. The production stage requires strict control of processes and environments to prevent any potential safety incidents. Unlike other supply chains, sales companies typically possess the specialized knowledge and skills necessary for handling hazardous materials, including deep market understanding, risk assessment capabilities, and emergency response measures, allowing them to better control and mitigate risks. The logistics stage must ensure that transportation and distribution meet the highest safety standards, and end users must be educated on safe usage practices. Referring to the application of blockchain technology in various supply chain sectors, we have divided the supply chain into five parts: raw material supply, production, sales, logistics, and end users. This division helps to clarify responsibilities and obligations while facilitating regulation, thereby enhancing the safety and transparency of the supply chain.

2.2. Blockchain-Based Access Control Method

Recent advancements in blockchain technology have enabled innovative solutions for access control in various domains. Wang et al. [15] proposed a method that combines blockchain’s decentralized and immutable features with Role-Based Access Control (RBAC) and proxy re-encryption technologies. By storing and managing encrypted access control policies and permissions on the blockchain, this approach automates verification and re-encryption processes, ensuring data security and transparent permission management. Additionally, the use of a Key Generation Center (KGC) enhances public and private key management, further improving security. J.P. Cruz et al. [16] introduced a Role-Based Access Control (RBAC-SC) system on the Ethereum platform. In this system, smart contracts enable authorities to create, manage, and revoke roles on the blockchain, ensuring transparency and auditability. These contracts incorporate built-in permission controls, allowing only authorized users to perform sensitive operations. By implementing smart contracts and a challenge-response verification protocol, the system provides a secure, decentralized, and transparent mechanism for cross-organizational role management, thereby reducing management costs and complexity. Furthering blockchain applications in access control, Zhang et al. [17] presented a smart contract-based framework for IoT systems. This framework includes multiple Access Control Contracts (ACCs), a Judge Contract (JC), and a Register Contract (RC) to facilitate static and dynamic access validations for subject–object pairs. A case study demonstrated the deployment and management of these contracts on an Ethereum platform within an IoT system, achieving distributed and trustworthy access control. In another innovative approach, Du et al. [18] proposed a blockchain-based access control architecture that integrates Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs) to achieve user authentication and authorization. Smart contracts automatically execute the authorization and access control processes, eliminating the need for human intervention.

Collectively, these studies highlight the potential and versatility of blockchain-based access control methods. By leveraging blockchain’s inherent security and transparency, these approaches address various challenges in access control across different domains, from enterprise IoT systems to cross-organizational role management, thereby enhancing security, efficiency, and trustworthiness in managing access rights.

2.3. Other Access Control Methods

In recent years, extensive research has been conducted in the field of access control technologies. Zhou et al. [19] introduced a system named Heracles, which employs capability-based access control using secure unforgeable tokens and integrates centralized policy management with distributed execution through a three-tiered architecture. This enhances the system’s responsiveness and scalability, providing an effective solution for the complex access control challenges in enterprise Internet of Things (IoT) environments. Expanding on access control mechanisms, Yang [20] proposes an integer linear programming (ILP)-based method to verify and resolve Separation-of-Duty (SoD) constraints in attribute-based access control (ABAC) systems. This method calculates the minimum number of users required to satisfy SoD constraints and resolves violations by minimizing user operation restrictions, thereby enhancing the integrity and efficiency of ABAC systems. Further advancing the field, Outchakoucht et al. [21] proposed a machine learning-based access control framework designed to enhance the security of IoT applications. They demonstrated the practicality and effectiveness of their framework, which lies at the intersection of IoT and machine learning applications, through a smart city case study, emphasizing the use of organizational and attribute concepts to avoid role explosion issues while providing a comprehensive security solution for IoT environments. In the context of healthcare IoT systems, Ashouri-Talouki [22] proposed a revocable multi-authority attribute-based encryption method. This method employs non-monotonic access policies and anonymous certificates to protect user privacy, resist collusion attacks, and ensure backward secrecy. The decentralized architecture enhances data security and efficiency while reducing communication and computational costs.

Together, these studies reflect the advancements and diversification in other access control methods, showcasing innovative approaches that integrate various technologies to address specific security and efficiency challenges in different domains.

2.4. Smart Contract

In the Bitcoin network, transactions are typically limited to simple cryptocurrency transfers, supporting only basic script operations such as hash verification and digital signatures. However, with the further development of blockchain technology and the diversification of user demands, the need for complex transactions and protocols has increased. To meet these demands, Ethereum introduced smart contract technology. Meanwhile, Hyperledger Fabric achieves similar functionality through chaincode (on-chain code), allowing developers to automatically execute, manage, or enforce contract terms when specific conditions are met. These chaincodes provide greater control and privacy for enterprise-level applications within Fabric’s architecture. By operating on a decentralized blockchain rather than centralized servers, smart contracts enable multiple parties to reach shared outcomes in an accurate, timely, and tamper-proof manner. Technically speaking, a smart contract is a program that contains data and executable code [23]. Smart contracts are not controlled by a central administrator, and are less susceptible to single-point attacks by malicious entities. When applied to multi-party digital protocols, smart contract applications can reduce counterparty risk, increase efficiency, lower costs, and provide new transparency to processes.

2.5. Hyperledger Fabric

Hyperledger Fabric [24] is an open-source enterprise-grade blockchain framework led by the Linux Foundation and designed to meet diverse business needs. In Fabric, smart contracts are called chaincode, which can be written in various programming languages and executed on the blockchain network. Fabric supports multiple consensus mechanisms, allowing users to choose an appropriate consensus algorithm such as Kafka and Raft for their application scenarios. Its main components include peer nodes, ordering nodes, and membership service nodes. Peer nodes store the blockchain ledger and execute chaincode, ordering nodes handle transaction ordering and block generation, and membership service nodes manage user identity authentication and authorization. Hyperledger Fabric is widely used in supply chain management, financial services, healthcare, trade settlement, and other fields. Due to its flexible architecture and robust privacy protection mechanisms, it has become the preferred choice for enterprise blockchain solutions. Through these features and components, Fabric provides a flexible, secure, and efficient blockchain platform suitable for various complex business application scenarios. Many blockchain-related research papers [25,26,27,28] utilize Hyperledger Fabric as the experimental platform for testing and validation.

3. Research Methods

3.1. Encrypted Data

Initially, before submitting a supply chain transaction (ti) to the blockchain, the submitting user (u) first generates a sufficiently strong random symmetric encryption key $K_i$ to protect all the data contained in the transaction. This key $K_i$ is used to encrypt the transaction data, producing the ciphertext $C_i$, which ensures the confidentiality and integrity of the transaction content during transmission and storage. To ensure the uniqueness and tamper-resistance of the transaction, after encryption the submitter calculates the hash value of the transaction data $H_i$. This hash value $H_i$ is generated using a secure hash algorithm such as SHA-256, and is used to verify that the transaction content has not been tampered with after submission. To distinguish the transaction identifier generated after uploading to the blockchain and ensure the security of the transaction data, the submitter encodes the hash value $H_i$ using base64, producing $H_i^{\prime }$, then submits $H_i^{\prime }$ as the unique identifier of the transaction in the blockchain network. In this way, the base64-encoded hash value $H_i^{\prime }$ becomes the key identifier for verifying and tracing the validity and integrity of the transaction.

This method not only ensures the confidentiality and security of the supply chain transaction data but also makes the records of transactions on the blockchain highly verifiable and tamper-resistant through the use of the hash value $H_i$ and base64 encoding. Submitters and participants can check and verify $H_i^{\prime }$ to ensure that the transaction data have not been accessed or modified without authorization during submission and processing, thereby establishing a trusted supply chain transaction recording system.

3.2. Defining Transaction Sets

In supply chain management, the “from” and “to” attributes are crucial, as they define the flow path of goods or assets within the supply chain. First, in order to effectively manage these transaction relationships in the supply chain, we introduce the concept of TXset. For each hazardous materials supply chain entity, we create a TXset in order of occurrence within the supply chain. When processing each transaction $t_i$ in the hazardous materials supply chain, the transaction data are encrypted and uploaded to blockchain storage, generating a unique identifier $t{x}_i$ that ensures the transaction’s uniqueness and immutability. This $t{x}_i$ is then added to the TXsets corresponding to the entities in the “from” and “to” attributes of this transaction $t_i$.

To accelerate the traceability of hazardous materials, it is necessary to update the TXsets associated with $t{x}_i$ in real time in addition to the “from” and “to” TXsets; for example, if a transaction $t_k$ involves the flow path (from: Sale Company, to: Logistics Provider1) of hazardous materials, upon processing this transaction both the Sale Company and Logistics Provider TXsets will be updated with $t{x}_k$. Additionally, if there was a previous transaction $t_j$ in the same batch of hazardous materials before $t_k$, in this case with the path (from: Manufacture1, to: Sale Company), we also add the blockchain-stored $t{x}_j$ to the Logistics Provider’s TXset. In this way, when we obtain any $t{x}_i$ within the supply chain, it is possible to search using $t{x}_i$ in order to quickly understand the overall flow path of that transaction. For example, when obtaining $t{x}_k$, it is known that the TXsets of Manufacture1, Sale Company, and Logistics Provider all contain this transaction, thereby revealing the flow path of the hazardous material (Manufacture1→ Sale Company → Logistics Provider1).

To ensure the correctness and completeness of the TXset, we first define the correctness and completeness of the transaction set. Correctness means that all transactions included in the TXset are valid and that each supply chain entity’s TXset should not contain transactions that do not belong to that set, while completeness means that each supply chain entity’s TXset should include all transactions that have passed through that entity and should not omit any transactions that qualify. The integrity and correctness of the method proposed in this paper can be discussed via the following scenarios: first, if transactions that should not be included are added to the TXset, any user with access to the TXset can detect and verify the transactions within it, thereby ensuring its correctness; second, if tampered transactions are added to the TXset, then the content of the transactions can be checked against the blockchain ledger to detect any tampering, ensuring the integrity and correctness of the data; finally, if the TXset lacks transactions that should be included, the ledger can be traversed to check for any missing transactions, thereby ensuring its completeness. Through these methods, the correctness and completeness of the TXset can be ensured, guaranteeing the transparency and security of the supply chain transactions.

3.3. Access Control Methods

In previous studies [29,30], smart contracts have been widely used to manage access control policies. By automatically executing access authorizations, smart contracts significantly enhance the efficiency and flexibility of policy management. Applying smart contracts to access control is a common and effective method. After uploading a batch of hazardous materials supply chain data to the blockchain, it is necessary to initialize the smart contract and designate the administrator roles for these hazardous materials before invoking the smart contract to assign user permissions for specific transaction sets (TXset). Subsequent authorization and revocation operations must verify whether the operation was performed by an administrator in order to ensure the security and compliance of the system.

In the smart contract, a table is created for each TXset that stores the hash values of authorized users. By adding or deleting user hash values in the corresponding TXset table, it is possible to grant or revoke permissions. This method not only improves the efficiency of access control management but also enhances the security and flexibility of the system. The specific implementation is shown in Algorithms 1 and 2.

Algorithm 1: GrantAccess

Algorithm 2: RevokeAccess

   In order to make the access control method more flexible, we introduce a mechanism for users to request access permissions. Ordinary users can submit access requests through RequestAccess, while administrators can approve or reject these requests via ApproveAccessRequest and RejectAccessRequest. This mechanism not only enhances the system’s dynamism and flexibility but also improves manageability and user experience in access control. In practical applications, the user access request process effectively balances security and convenience, ensuring that only authorized users can access sensitive data. The specific implementation is shown in Algorithms 3–5.

Algorithm 3: RequestAccess

    The reason for introducing this request and approval mechanism is that traditional access control methods are often too rigid and cannot adapt to constantly changing user needs and access environments. By allowing users to submit access requests, the system can dynamically adjust permission allocation and respond promptly to new access demands. At the same time, the administrator’s approval operations ensure strict access control, preventing unauthorized access.

This method is particularly important in the context of blockchain and smart contract applications. Due to the immutability and transparency of blockchain data, the flexibility and security of access control are crucial; therefore, access control strategies implemented through smart contracts combined with the user request and administrator approval mechanism can enhance the system’s security and reliability while also improving its adaptability and scalability.

Algorithm 4: ApproveAccessRequest

Algorithm 5: RejectAccessRequest

3.4. System Architecture

In the blockchain access control system described in this study, each blockchain node is equipped with a dedicated Transaction Coordinator (TXCO) component to achieve decentralized access control. As shown in Figure 2, the system is designed to ensure data security and integrity while providing a flexible permission management mechanism. Data owners process and submit data to the blockchain through the transaction coordinator, which is responsible for encrypting, signing, and storing the submitted data to ensure the confidentiality and integrity of the data during transmission and storage. Authorized users can read the data after the transaction coordinator verifies their access permissions. This process includes permission verification, data decryption, and access log recording, ensuring that only authorized users can access sensitive data and that all access operations are logged for audit purposes. Additionally, the transaction coordinator supports the deployment and execution of smart contracts, further enhancing the system’s automation and flexibility. Smart contracts can define complex access control policies and data processing logic, enabling the system to automatically execute various operations based on predefined rules. This decentralized access control mechanism improves the system’s security and reliability while reducing reliance on a central control entity, reflecting the decentralization advantages of blockchain technology.

3.4.1. Transaction Coordinator

The Transaction Coordinator (TXCoordinator) plays a crucial role in the blockchain access control system, allowing different types of users to interact with it in order to handle sensitive content in transactions while ensuring the security and integrity of the data. The transaction coordinator manages the privacy of transaction data by implementing the TXCoordinator interface. Specifically, after processing the transaction data, the transaction coordinator calls the smart contract SubmitTransaction to securely upload the processed data to the blockchain, then invokes the CreateTXset method to create a transaction set. Each transaction set is assigned a unique name and the transaction identifier returned by the blockchain is mapped to the key for the encrypted private data, ensuring the traceability and security of the data. Additionally, the transaction coordinator has a permission verification function. Its CheckAccess method is used to verify whether a user requesting data access has the appropriate permissions. As described in Section 3.3, this method performs permission checks by calling smart contract functions, ensuring that only authorized users can access sensitive data.

3.4.2. User Case

As illustrated in Figure 3, where Bob is the data submitter and Alice is the data reader, the process begins with the data submitter (Bob) submitting the data he wishes to record on the blockchain to the Transaction Coordinator. The Transaction Coordinator processes and securely ingests the data into the blockchain. Subsequently, it executes additional methods within the coordinator, such as creating a TXset, initializing access control smart contracts, and other necessary operations. In terms of data access, when the data accessor (Alice) wishes to access specific data, she must submit an access request through the Transaction Coordinator. This request is first sent to the blockchain node, where an internal mechanism verifies Alice’s access permissions to ensure that only authorized users can access sensitive or private data. When Alice’s access rights are confirmed, she can receive the required data from the Transaction Coordinator. Additionally, Alice has the ability to verify whether the data received from the Transaction Coordinator have been tampered with. If Alice is not authorized to access certain data, she can formally request the necessary access permissions from the blockchain system, ensuring compliance and security in data access. Furthermore, the system places a strong emphasis on the verification of data consistency, ensuring the integrity and accuracy of the entire system’s data through continuous cross-checks among multiple nodes in the blockchain. This decentralized verification mechanism not only enhances the system’s security but also improves the transparency of data management. This blockchain access control system is particularly suitable for application scenarios that require stringent data security and high data consistency. The design leverages the core advantages of blockchain technology, such as decentralization, data immutability, and high transparency, effectively improving the efficiency and reliability of data processing and access control.

4. Experimental and Evaluation

4.1. Experimental Setup

To empirically analyze these methods, we constructed a blockchain network instance based on Hyperledger Fabric version 2.2. The network architecture included three peer nodes and two orderer nodes, each of which was independently deployed on separate computing nodes. All nodes were configured as virtual machines with two vCPUs, 8 GB of memory, and 50 GB of storage. In terms of network configuration, the peer nodes were deployed in Oregon, USA, while the orderer nodes were deployed in Singapore. The network employed the Raft consensus algorithm to ensure transaction consistency and reliability across the network. Data storage utilized Fabric’s default LevelDB database. The smart contracts, referred to as chaincode in Fabric, were written in the Go programming language.

By setting up the experiment in this manner, it was possible to test the proposed methods on geographically distributed nodes, thereby validating their performance and reliability under different network conditions. The results of these experiments provide deep insights into the effectiveness and feasibility of blockchain systems in real-world application scenarios.

4.2. Hazardous Materials Supply Chain Simulation Data

As shown in Figure 1, to simulate the hazardous materials supply chain data we developed a hazardous materials supply chain data generator. This generator was based on a predefined hazardous materials supply chain topology including nodes and edges, with each node representing an entity within the supply chain and the edges representing the logistical links. Raw material suppliers serve as the starting nodes that create hazardous materials and send them to the subsequent node. Other intermediate nodes can only forward the hazardous materials they receive, while end users act as terminal nodes that cannot forward items and only receive hazardous materials. Asphalt plays an important role in modern industry and infrastructure construction due to its excellent physical properties and wide range of applications; however, due to its hazardous nature it is necessary to minimize risks through effective supply chain management measures in order to ensure worker safety and environmental protection. We selected asphalt, a common hazardous material, and predefined data for ten types of asphalt for each node based on their characteristics. The generator appropriately connects the nodes and edges, ultimately providing hazardous asphalt supply chain data for experimental testing, with the supply chain containing 110 transactions.

4.3. Baseline

Considering the absence of a transaction coordinator, we stored each transaction set on a separate blockchain. To maintain consistency between these transaction sets and the main blockchain that stores all transactions, we chose to use the two-phase commit (2PC) protocol. This ensures that each operation either succeeds or fails simultaneously on all related blockchains, achieving overall data consistency and atomicity in the system. This approach ensures that the state of all transaction data can be accurately synchronized and maintained even in a distributed and decentralized environment. Two-phase commit (2PC) is a classic solution for ensuring data consistency across multiple nodes in a distributed system. By dividing the transaction operation into “prepare” and “commit” phases, 2PC effectively coordinates each node, ensuring that either they all commit the transaction or that none do. This is crucial for maintaining system state consistency. 2PC is widely used in both industry and academia, particularly in scenarios requiring cross-system coordination, but faces issues with blocking and single point of failure risk, as coordinator failure can lead to system stalling. Additionally, the protocol encounters high latency and scalability challenges in large distributed systems due to its multiple communication rounds. Nonetheless, using it as a baseline helps to measure the practicality and effectiveness of other methods in real-world applications. 2PC provides a benchmark for new or improved protocols. By using it as a baseline in experiments, the differences in performance, reliability, or other key metrics between new methods and known methods can be clearly demonstrated.

4.4. Result

Throughput is typically used to measure the number of tasks a system can handle in a given period. In computer systems, throughput can be used to evaluate the server’s capacity to handle requests, the network’s data transmission capability, etc. In blockchain networks, throughput is commonly measured using the number of transactions processed per second (TPS) to assess the network’s transaction rate performance, as shown in Equation (1).

$$\mathrm{TPS}={\displaystyle \frac{\mathit{Transactions}}{T_{\mathrm{end}}-T_{\mathrm{begin}}}}$$

(1)

As shown in Figure 4, when the number of concurrent requests is 5, the TPS difference between the baseline 2PC and the proposed method is not significant; however, as the number of concurrent requests gradually increases, the performance gap between the two methods widens considerably. When the number of concurrent requests exceeds 25, 2PC fails to handle the large volume of transactions, resulting in system unresponsiveness. In contrast, the proposed method maintains a TPS exceeding 200 even when the number of concurrent requests reaches 45.This phenomenon indicates that the proposed method demonstrates significant superiority in high-concurrency environments. Specifically, as the number of concurrent requests increases, the baseline 2PC is limited by its synchronization mechanism and transaction locking mechanism, which hinders its ability to effectively scale concurrent processing capacity, ultimately leading to system failure. In comparison, the proposed method optimizes the transaction processing workflow and enhances the system’s parallel processing capability, enabling it to sustain high throughput under high concurrency conditions.

Latency refers to the time between sending a request and receiving a response. It is a crucial performance metric used to measure system responsiveness, particularly in network and computing systems. In blockchain systems, ‘latency’ refers to the time from submitting a transaction request to its confirmation and inclusion in the blockchain. This is a critical performance indicator, as it directly affects user experience and overall system efficiency.

As shown in Figure 5, when the number of concurrent requests reaches 15, although 2PC can still complete tasks under high latency, the latency of 2PC increases significantly as the number of concurrent requests increases, exceeding the latency of our proposed method by more than ten times under the same number of concurrent requests and eventually leading to system unresponsiveness. In contrast, the proposed method maintains relatively stable latency under varying numbers of concurrent requests. This result highlights the superior stability and performance advantage of the proposed method in high-concurrency environments. Specifically, when processing a large number of concurrent requests, 2PC is limited by its synchronization mechanism and transaction locking mechanism, making it difficult to effectively scale concurrent processing capabilities and leading to a sharp increase in latency, ultimately resulting system failure. In comparison, the proposed method optimizes the transaction processing workflow and enhances the system’s parallel processing capabilities, maintaining low latency and stable system response even under high-concurrency conditions.

Comparison with Other Methods

We compared the proposed system with two blockchain-based access control systems in terms of throughput and latency. The first is ABAC-SC [31] (Attribute-Based Access Control Contract), while the other is BPDAC [32] (Blockchain-Based and Provenance-Enabled Dynamic Access Control Scheme). ABAC-SC employs an attribute-based access control model through smart contracts, which evaluates whether the requester has the necessary permissions for the resource and records the access decision within the smart contract. On the other hand, BPDAC uses historical interaction records to make access decisions and store data provenance for tracking, an approach that addresses the limitations of static access control in dynamic cloud environments. The experimental data are provided in

Table 1. Comparison of throughput, latency, transactions per round, and number of rounds.

Method	TPS	Latency (ms)	Transactions per Round	Number of Rounds
Proposed	214	3023	110	45
BPDAC	160	2400	1000	10
ABAC-SC	241	2000	5000	10

for comparison. The results indicate that our proposed method performs well in terms of throughput (TPS), achieving 214 TPS. However, due to the deployment of our peer and orderer nodes on geographically distant servers, as opposed to the other two systems, which were deployed on the same computer, our system exhibits higher latency (3023 ms). Nonetheless, considering the impact of network latency, our approach maintains relatively stable performance in scenarios involving multiple transaction rounds.

5. Conclusions

In this paper, we introduce an access control system that integrates blockchain technology with hazardous materials supply chains. This system both enables the traceability of hazardous materials and allows for precise access control. Our contribution lies in designing and implementing an access control system architecture that integrates blockchain technology based on a proposed hazardous materials supply chain model architecture using simulated supply chain data. The proposed system has been validated on the Hyperledger Fabric platform, demonstrating its application in the management of hazardous materials supply chains such as asphalt while utilizing access control methods to manage permissions and track supply chain links. Each blockchain node is equipped with a transaction coordinator, which encrypts the hazardous materials data for submission to the blockchain for storage. Subsequently, we create corresponding transaction sets for each supply chain entity. Finally, we use smart contracts to enforce access control over these transaction sets. To validate the effectiveness of the proposed method, we compared it with the two-phase commit (2PC) mechanism as a baseline and conducted experiments using simulated asphalt supply chain data. The experimental results indicate that our proposed method significantly outperforms the baseline in terms of throughput and exhibits excellent performance in terms of latency, being both stable and lower than the baseline. These results fully demonstrate the superiority of our method in managing hazardous materials supply chains with high-concurrency and high-security demands. Moreover, by employing encryption technology and smart contracts, our method achieves effective protection and permission management of sensitive data, ensuring the security and privacy of each entity within the supply chain. Future research can further optimize the performance of this system and explore its potential applications in other high-risk and high-value supply chains. This study provides new perspectives and approaches for the application of blockchain technology in supply chain management, significantly enhancing transparency, security, and efficiency in supply chains.