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.

中文翻译：

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Groupchain：在物联网服务计算的雾计算中迈向可扩展的公共区块链


物联网（IoT）由分布在整个网络中的大量智能设备提供支持，为来自设备的海量数据提供服务计算。雾计算是基于云的物联网解决方案的延伸，随着分布式和去中心化的需求而出现。在这方面，与区块链的结合为去中心化提供了自然的解决方案，也有可能帮助雾计算克服安全和隐私等缺陷，从而扩大物联网的应用范围。然而，区块链与雾计算集成的关键挑战之一是可扩展性。为此，本工作提出了 Groupchain，一种新型可扩展的双链结构公共区块链，适用于物联网服务计算的雾计算。 Groupchain采用领导小组集体提交区块以提高交易效率，并将奖金和押金引入激励机制中以监督领导小组成员的行为。我们的安全分析表明，Groupchain保留了类比特币区块链的安全性，并增强了对双花和自私挖矿等攻击的防御能力。我们实现了 Groupchain 的原型并进行了实验。实验结果表明，Groupchain实现了比特币中所争论的交易吞吐量和确认延迟的优化。