Current industrial control systems in the Industry 4.0 era usually suffer from a variety of security issues, and important manufacturing data and instructions are vulnerable to attacks or tampering, for instance, tampering with product performance data during quality inspection. These counterfeit products are then used in many fields, causing unprecedented severe security problems. Another typical event is attacks on companies using viruses, which spread to other equipment and can eventually lead to the shutdown of production lines across factories. These events expose the fragility and weak information security of industrial control systems in the Industry 4.0 era. Current industrial control/management usually relies on a centralized platform, which suffers from inadequate interoperability between heterogeneous equipment, weak collaboration among operations, inadequate traceability of information, and weak robustness against system failures. Implementing tamper-proof security of product lifecycle data and industrial control systems in the Industry 4.0 era is a crucial problem and an essential way to improve transparency and brand credibility.

Blockchain is known as a new generation of secure information technology for realizing business and industrial sustainability. Much research on blockchain-empowered, smart, and sustainable manufacturing in the Industry 4.0 era has been conducted from technical, commercial, organizational, and operational perspectives. However, the progression and promotion of these blockchain applications have been fundamentally impeded by various issues in scalability, flexibility, and cybersecurity. Blockchain-empowered transformation of the manufacturing paradigm is still in its early stages. Many manufacturers have not progressed their blockchain solutions beyond proof-of-concept. Deploying blockchain-based intelligent applications is still difficult for manufacturers. Moving into a new technology space has always been a dilemma for conservative spaces. Challenges in the areas of techniques, social barriers, standards, and regulations impede progress, for example, the development of computationally efficient algorithms for real-time responses, the security of blockchain, and how to build a digital twin of the physical asset in blockchain-based service networks (BSN). Privacy protection issues in blockchain applications are also major concerns for users. There is an urgent need for breakthroughs and innovations in methods, technologies, and platforms for blockchain, smart contracts, and decentralized applications.

This Special Issue aims to collect state-of-the-art blockchain theories, models, methods, intelligent applications, and practical advances for achieving smart and sustainable manufacturing in the Industry 4.0 era, enhanced by advanced cryptographic mechanisms, networking protocols, machine learning techniques, and data analytics.

Potential topics include but are not limited to the following:

• Secure multi-party computing in large-scale blockchain applications
• Robust and highly efficient consensus algorithms
• Formal verification and debugging of smart contracts
• Middleware interfaces for multi-blockchains
• Digital twins of physical assets in the blockchain
• Big data analytics in blockchain applications
• Machine learning algorithms in blockchain applications
• Security models of blockchain
• Decentralized autonomous manufacturing
• Blockchain-secured digital twins
• Smart contract-enabled distributed digital twins
• Blockchain-based smart manufacturing systems
• Blockchain-based product lifecycle management
• Blockchain in Industry 4.0
• Blockchain as a service