My research interest is computer networks and security. Within this area my work focus is on distributed embedded systems; this domain may also be described as Wireless Sensor Networks (WSN), Cyber Physical Systems (CPS), or the Internet of Things (IoT). Most computer systems surrounding us in our daily life are no longer the traditional personal computers but embedded devices. Recently, these embedded devices have become increasingly networked together to form distributed embedded systems. Examples of networked embedded systems are home automation systems, physical intrusion detection systems, smart cities or wireless sensor systems for factory automation. Embedded devices are used to build critical infrastructures and we depend on their reliable operation. It is therefore essential to provide mechanisms which protect these infrastructures against human error, system faults and attacks. My work looks at communication mechanisms and the software used to construct these systems; with particular focus on constructing them in a secure fashion. An important aspect of my work is to deploy and test systems in real-world application scenarios.