Introduction

A consensus on the definition of the Internet of Things (IoT) has not yet been reached. Yet, it is unlikely that a comprehensive overview of the huge and growing class of IoT hardware components can be drawn, since they are less standardised than hardware for personal computers. To make things more complex, the IoT brings together devices with limited CPU, memory and processing power, such as pressure sensors that require small, low-cost hardware to be economically competitive, and devices with powerful processors and large memories. As a result, the first class of devices (resource constrained devices) does not have the necessary memory and computing power to run the most up-to-date and robust cryptographic protocols. Thus, research focuses on so-called “lightweight” cryptographic algorithms, which are more suitable for such constrained contexts. Like the IoT, the concept of resource-constrained devices remains vague as few technical taxonomies exist.