Ray-tracing assessment of the robustness of Physical Layer Security key generation protocol

Nowadays, information security is a very important topic. In particular, wireless networks are experiencing an ongoing widespread diffusion, also thanks the increasing number of Internet Of Things devices, which generate and transmit a lot of data: protecting wireless communications is of fundamental importance, possibly through an easy but secure method. Physical Layer Security is an umbrella of techniques that leverages the characteristic of the wireless channel to generate security for the transmission. In particular, the Physical Layer based-Key generation aims at allowing two users to generate a random symmetric keys in an autonomous way, hence without the aid of a trusted third entity. Physical Layer based-Key generation relies on observations of the wireless channel, from which harvesting entropy: however, an attacker might possesses a channel simulator, for example a Ray Tracing simulator, to replicate the channel between the legitimate users, in order to guess the secret key and break the security of the communication. This thesis work is focused on the possibility to carry out a so called Ray Tracing attack: the method utilized for the assessment consist of a set of channel measurements, in different channel conditions, that are then compared with the simulated channel from the ray tracing, to compute the mutual information between the measurements and simulations. Furthermore, it is also presented the possibility of using the Ray Tracing as a tool to evaluate the impact of channel parameters (e.g. the bandwidth or the directivity of the antenna) on the Physical Layer based-Key generation. The measurements have been carried out at the Barkhausen Institut gGmbH in Dresden (GE), in the framework of the existing cooperation agreement between BI and the Dept. of Electrical, Electronics and Information Engineering "G. Marconi" (DEI) at the University of Bologna.