Spacechain: A Three-Dimensional Blockchain Architecture for IoT Security

Deploying blockchain in IoT is an effective way to address traditional security issues. However, existing approaches have two major limitations: since the blockchain itself is subject to attacks, including selfish mining, double spending, and distributed denial of service attacks, IoT smart devices are also vulnerable once hackers successfully invade blockchain systems; due to the heterogeneity and resource limitations of IoT devices, the deployment of the existing blockchain systems in the IoT scenario cannot reflect strong adaptability and meet IoT service requirements. In this article, we introduce Spacechain, a secure and high-performance blockchain system with three-dimensional ledger architecture, to enable blockchain open in IoT. Specifically, we first design a three-dimensional architecture with novel data structures to deal with the heterogeneity and scalability of IoT networks. Then, we propose the Three-Dimensional Greedy Heaviest-Observed Sub-Tree (3D-GHOST) consensus mechanism for Spacechain to improve security and network performance. Additionally, we conduct detailed security analysis and extensive experimental verification to demonstrate the performance of Spacechain.