Abstract

These days, IoT devices are deployed at a massive scale, with Cisco predicting 20 billion devices by the year 2020. As opposed to endpoint devices, IoT devices are resource-constrained devices, incapable of securing and defending themselves, and can be easily hacked and compromised. Fog computing can augment such capacity limitations by providing localized compute, storage, and networking for a group of IoT devices. As fog nodes are deployed in close proximity to IoT devices, fog computing can be more effective than cloud computing. Furthermore, Blockchain has emerged as technology with capabilities to provide secure management, authentication and access to IoT devices and their data, in decentralized manner with high trust, integrity, and resiliency. In this paper, we propose a user authentication scheme using blockhain-enabled fog nodes in which fog nodes interface to Ethereum smart contracts to authenticate users to access IoT devices. The fog nodes are used to provide scalability to the system by relieving the IoT devices from carrying out heavy computation involving tasks related to authentication and communicating with the blockchain. We describe system components, architecture and design, and we discuss key aspects related to security analysis, functionality, testing and implementation of the smart contracts. The full code of the smart contracts for authentication registry, lists, rules and logic is also made publicly available at Github.