Towards trusted data on decentralized IoT applications: Integrating blockchain in constrained devices

Blockchain technology is attracting the interest of the Internet of Things (IoT) domain as a decentralized platform for a trusted record of information. Thus, an increasing number of architectures have been proposed for integrating both technologies. However, few of them have focused on the sensing elements of the IoT systems, which are typically low-cost and resource-constrained devices. In this work, we propose an architecture that integrates blockchain at the sensor level, creating a chain of trust from the source of the data. To evaluate our proposal, we develop a cross-platform library for constrained IoT devices and deploy a full-fledged utilities management showcase using off-the-shelf hardware. From a device perspective, we measure the overhead that our architecture introduces in the system, in terms of memory and program space footprint, processing time, and power consumption. From the application perspective, we quantify the additional cost and delay incurred by using a public blockchain. Our results show that even constrained 8-bit devices with a 16-MHz AVR CPU can support the proposed solution. Moreover, the cost of maintaining a transparent record of daily resource consumption on the blockchain can be less than 1 USD a month.