In the Internet of Things (IoT) vision, conventional devices become smart and autonomous. This vision is turning into a reality thanks to advances in technology, but there are still challenges to address, particularly in the security domain e.g., data reliability. Taking into account the predicted evolution of the IoT in the coming years, it is necessary to provide confidence in this huge incoming information source. Blockchain has emerged as a key technology that will transform the way in which we share information. Building trust in distributed environments without the need for authorities is a technological advance that has the potential to change many industries, the IoT among them. Disruptive technologies such as big data and cloud computing have been leveraged by IoT to overcome its limitations since its conception, and we think blockchain will be one of the next ones. This paper focuses on this relationship, investigates challenges in blockchain IoT applications, and surveys the most relevant work in order to analyze how blockchain could potentially improve the IoT.

In the Internet of Things (IoT) a worldwide network of sensors and actuators transmit data and actuate over the Internet. Nevertheless, the deployment of sensors and actuators usually requires tools to program and configure them before they can work, and not everyone has such access. Current smartphones are provided with a large set of sensors and actuators that can be incorporated in the IoT. With the aim of achieving seamless integration, this paper presents SocICoAP, a system that enables the sharing of sensors and actuators present in smartphones and installing custom ones at run-time in microcontrollers. In this way smartphones are integrated into the IoT, not only a sensor providing data from its built-in sensors but also as a gateway for nearby deployed sensors. Furthermore, the sensor data can also be globally shared and analysed through a cloud computing integration.

Wireless sensor and actuator networks (WSAN) constitute an emerging technology with multiple applications in many different fields. Due to the features of WSAN (dynamism, redundancy, fault tolerance, and self-organization), this technology can be used as a supporting technology for the monitoring of critical infrastructures (CIs). For decades, the monitoring of CIs has centered on supervisory control and data acquisition (SCADA) systems, where operators can monitor and control the behavior of the system. The reach of the SCADA system has been hampered by the lack of deployment flexibility of the sensors that feed it with monitoring data. The integration of a multihop WSAN with SCADA for CI monitoring constitutes a novel approach to extend the SCADA reach in a cost-effective way, eliminating this handicap. However, the integration of WSAN and SCADA presents some challenges which have to be addressed in order to comprehensively take advantage of the WSAN features. This paper presents a solution for this joint integration. The solution uses a gateway and a Web services approach together with a Web-based SCADA, which provides an integrated platform accessible from the Internet. A real scenario where this solution has been successfully applied to monitor an electrical power grid is presented.

It is being more than 30 years since first researches in Wireless Sensor and Actor Networks (WSAN) started to appear. However, despite been acknowledged one of the top emerging technologies for the 21st century, WSANs are not still a ubiquitous technology. Factors that have hindered its development are the lack of standards and protocols that support QoS and the complexity of designing and implementing WSAN applications. This thesis focus on overcoming these factors by means of a middleware that provides: 1) QoS support, necessary for applications such as the Protection of Critical Infrastructures (CIP), and 2) a flexible programming abstraction that helps the developer to implement WSAN applications and specify their QoS requirements without having to deal with low level repetitive tasks.