DIoTA: DecentralizedLedgerBased Framework for Data Authenticity Protection in IoT Systems It is predicted that more than 20 billion IoT devices will be deployed worldwide by 2020. These devices form the critical infrastructure to support a variety of important applications such as smart city, smart grid, and industrial internet. To guarantee that these applications work properly, it is imperative to authenticate these devices and data generated from them. Although digital signatures can be applied for these purposes, the scale of the overall system and the limited computation capability of IoT devices pose two big challenges. In order to overcome these obstacles, we propose DIoTA, a novel decentralized ledgerbased authentication framework for IoT devices. DIoTA uses a twolayer decentralized ledger architecture together with a lightweight data authentication mechanism to facilitate IoT devices and data management. We also analyze the performance and security of DIoTA, and explicitly give the major parameters an administrator can choose to achieve a desirable balance between different metrics.

Communication Aspects of the Integration of Wireless IoT Devices with Distributed Ledger Technology The pervasive need to safely share and store information between devices calls for the replacement of centralized trust architectures with decentralized ones. DLTs are seen as the most promising enabler of decentralized trust, but they still lack technological maturity, and their successful adoption depends on the understanding of the fundamental design tradeoffs and their reflection in the actual technical design. This work focuses on the challenges and potential solutions for an effective integration of DLTs in the context of the Internet of Things (IoT). We first introduce the landscape of IoT applications and discuss the limitations and opportunities offered by DLTs. Then we review the technical challenges encountered in the integration of resourceconstrained devices with distributed trust networks. We describe the common traits of lightweight synchronization protocols, and propose a novel classification rooted in the IoT perspective. We identify the need for receiving ledger information at the endpoint devices, implying a twoway data exchange that contrasts with the conventional uplinkoriented communication technologies intended for IoT systems.