Groupchain: Towards a Scalable Public Blockchain in Fog Computing of IoT Services Computing

Powered by a number of smart devices distributed throughout the whole network, the Internet of Things (IoT) is supposed to provide services computing for massive data from devices. Fog computing, an extension of cloud-based IoT-oriented solutions, has emerged with requirements for distribution and decentralization. In this respect, the conjunction with Blockchain provides a natural solution for decentralization, as well as potentially helps fog computing overcome some deficiencies such as security and privacy then consequently expand the application scope of IoT. However, one of the key challenges of blockchain's integration with fog computing is scalability. To end this, this work proposes Groupchain, a novel scalable public blockchain of a two-chain structure suitable for fog computing of IoT services computing. Groupchain employs the leader group to collectively commit blocks for highertransaction efficiency and introduces bonus and deposit into the incentive mechanism to supervise behaviors of members in the leader group. Our security analysis shows that Groupchain retains the security of Bitcoin-like blockchain and enhances defense against attacks such as double-spend and selfish mining. We implement a prototype of Groupchain and conducted experiments. The experimental results demonstrate that Groupchain achieves optimization on transaction throughput and confirmation latency which are argued in Bitcoin.