  There has been increasing interest in the potential of blockchain in
enhancing the security of devices and systems, such as Internet of Things
(IoT). In this paper, we present a blockchain-based IoT security architecture,
IoTchain. The three-tier architecture comprises an authentication layer, a
blockchain layer and an application layer, and is designed to achieve identity
authentication, access control, privacy protection, lightweight feature,
regional node fault tolerance, denial-of-service resilience, and storage
integrity. We also evaluate the performance of IoTchain to demonstrate its
utility in an IoT deployment.
