The Internet of Things (IoT) paradigm is one of the most promising innovations of information technology. It is predicted that there will be 50 billion devices connected to the internet by 2020. Though the internet is deployed on a large-scale in many kinds of scenarios, including smart cities, industrial IoT, Internet of Vehicles, and so on, it is more vulnerable due to constrained resources. The traditional client-server architecture yields many significant limitations to meet the security demands of IoT, such as relying on the trusted server, incapability for time-sensitive applications, and high data maintenance cost.

Blockchains, like Bitcoin and Ethereum, have achieved great success beyond our expectations. Blockchain is a decentralized platform in which each node stores a copy of the whole ledger. The blockchain is perceived as a promising technique for scaling IoT security. However, it is still unclear exactly how blockchain technology can be used in this way; there is still no general framework of leveraging the blockchain technique for enhancing the security of IoT. Leveraging blockchain architecture in IoT is still a challenging research direction.

Thus, this Special Issue will mainly focus on the challenges of blockchain and decentralized techniques for IoT. Original research and review articles are welcome.

Potential topics include but are not limited to the following:

• Blockchain architecture for decentralization in IoT security
• Decentralized consensus for IoT security
• Smart contract for IoT security
• Lightweight decentralized protocols for IoT security
• Lightweight ledger structure for IoT security
• Blockchain-based security protocol for IoT security
• Lightweight and secure multi-party computation protocol for IoT security
• Blockchain for secure edge computing security
• Blockchain for secure fog computing security
• Blockchain for IoT-enabled critical verticals and sectors (energy, transport, health, water, etc.)
• Blockchain for Industrial Internet of Things (IIoT) security
• Blockchain for Cyber-Physical Systems (CPS) security