Public defence in Signal Processing for Communications, M.Sc. (Tech.) Henri Hentilä

The title of the thesis: Secret Key Generation for Secure Wireless Internet of Things

Doctoral student: Henri Hentilä
Opponents: Prof. Valtteri Niemi, University of Helsinki, and Prof. Rafael Schaefer, Technical University of Dresden, Germany
Custos: Prof. Visa Koivunen, Aalto University School of Electrical Engineering, Department of Information and Communications Engineering 

In the Internet of Things (IoT), hundreds or even thousands of devices are envisioned to be communicating over shared radio spectrum, enabling a variety of applications from Smart Homes and Smart Cities to real-time monitoring of a person’s health. However, due to the broadcast nature of wireless transmissions and the large number of communicating devices, ensuring the privacy and security of data in IoT is a serious challenge. Existing encryption protocols are seen as too demanding for IoT in terms of the computation and communication required, in addition to which they are vulnerable to quantum computers (which are expected to become a reality in the next decade or so). 

This thesis studies an alternative form of secrecy protocol, which can be made quantum-safe and which results in only a marginal increase in computation and communication compared to non-secret communication. Specifically, it studies the problem of generating a shared secret key between two communicating parties by exploiting the physical properties of the wireless channel between them, such as its randomness and reciprocity. The generated key can subsequently be used in lightweight encryption to achieve secure communication, with said key generation replacing the computationally demanding public key step of conventional encryption protocols. 

Contributions of the thesis include new theoretical bounds on the best achievable key generation rates, as well as proposing and studying the performance of more practical key generation protocols for IoT. The new theoretical bounds provide a means to more precisely quantify the optimality of key generation protocols than what was possible before, particularly when these protocols are subject to constraints on computation and communication. Meanwhile, the proposed practical protocols are shown to provide state-of-the-art performance close to the theoretical bounds.

Thesis available for public display 10 days prior to the defence at: https://aaltodoc.aalto.fi/doc_public/eonly/riiputus/

Contact information:

Doctoral theses in the School of Electrical Engineering: https://aaltodoc.aalto.fi/handle/123456789/53