Dynamic Key Distribution for Secure Group Communications in Constrained Environments

Group communication – especially in form of multicast – is a famous communication pattern in constrained networks, e.g. in the Internet of Things (IoT), Wireless Sensor Networks (WSN) or Device to Device (D2D) communication. However, it comes with mandatory management overhead during the life-cycle of a group, which is usually favored due to the potential energy savings ones the connection is set up. The management paradigm worsens, if the connection within and the management of the group has to be secure and in turn requires security management. Security and cryptography, however, need special attention when used in constrained environments. The proposed thesis will connect group management, group communication and security management and apply them to constrained environments. INTRODUCTION MOTIVATION Group communication has been discussed for decades, mostly within computer networking and social messengers. Nowadays, most smartphone messengers offer the formation of groups in order to achieve discussion of several people on a certain topic or interest. Groups have members and administrators, the communication itself is a 1:n communication pattern, where one device is sending data to a group of receivers, the so called multicast. In classical computer networks, multicast is mostly used for streaming applications. Clients subscribe to and the server sends data to a specific multicast address while the network takes care of the distribution. Other forms of group communication are the n:1 communication pattern, where a group of people sends data to single receiver(s) outside the group. A common example for this pattern are receiver initiated MAC protocols (Sun et al., 2008). The specification of n:m communication pattern is selfexplanatory, however, please note that 1:1 communication might be a valid form of group communication as well. Scenarios with networks of constrained devices (like embedded systems) and network technologies (like Internet of Things) can benefit from dynamic formation of communication groups. First, this form of communication often saves bandwidth and in turn energy, increasing the life time of battery driven devices. Second, the existence of a communication group eases distribution of data as the interested receiver registers beforehand and does not have to be discovered ad-hoc, examples being the distribution of control information (e.g. in Smart Homes/Cities), but also firmware updates for a certain group of devices. The goal of this PhD thesis is to benefit from the advantages of group communications in constrained systems while preserving security. Thus, it will develop a system to evaluate the efficiency of secure group communication and the inherent key management solutions, covering the life-cycle of a communication group. The methodology being used will present models covering the key management during the different group management actions. The system will be developed according to these models in order to ensure its completeness and to produce reproducible results for the research community. Evaluated solutions will either be optimized to achieve better efficiency or shown impracticable for specific system or scenario classifications. With this results at hand, recommendation on scenario specific configuration for key management can be developed.